The Road Pricing Post

I’ve been writing pieces of this post for more than a year, but parts go back to presentations I’ve given several years before. As I’ve written it it’s gotten longer and longer, so I broke it down into several sections and case studies in each. It’s mostly about road pricing but also touches on bottlenecks and congestion. It’s not meant to be exhaustive, but it may well be exhausting to read. Enjoy?

In 1996, Massachusetts Governor Bill Weld was running for Senate against John Kerry. In a last-minute ploy to gain votes, he suspended tolls on part of the Turnpike, making a show of taking out the tolling (seen here yukking it up with Big Dig podcast villain Jim Kerasiotes). In 2014, when the tolls made a valiant return, I wrote about how, for nearly two decades, they had incentivized people to take a slightly longer (by time, not distance) trip to avoid the tolls, adding traffic congestion to local streets. Jim and Bill didn’t exactly do the math: while people will generally pay tolls for a fast trip on a highway, if the tolls are easily avoidable, they’ll choose to avoid them.

Believe it or not, time has a value. 25¢ to save two minutes in 1997 is $7.50 per hour (about $16 today). Make it $1 for those same two minutes is $30 per hour ($64 today). People are actually rational individuals and, if given a substitute good at a reasonable price, will make a different decision. Yet it seems like many toll policymakers, whether in the public sector or private, have never heard of this newfangled field of “economics,” and make the same mistakes again and again.

So here is a 13,000 word blog post with more than you ever wanted to know about toll road policy. With a sprinkling of economics. (Disclaimer: I am not an economist, but I do know some basic math.)

I. Where tolls do and don’t work
—a. Where tolls do work
—b. Where tolls don’t work
II. One-way tolling
—a. Case Study: the Delaware
—b. Case Study: the Dumbarton Bridge
III. Parallel routes: substitute goods
—a. Case Study: Chicago Skyway
—b. Case Study: Indiana Toll Road
—c. Case Study: Louisville
—d. Case Study: Oregon
—e. Case Study: Vancouver
—f. Case Study: Bay City, Michigan
IV. Volume discounts, in-state discounts, marginal rates and the commerce clause
—a. Case Study: Louisville (again)
—b. Case study: Maine
—c. Case study: Massachusetts in-state discounts
V. AET, ORT and, uh … why is Maine still building toll booths?
—a. Case Study: New Hampshire
—b. Case Study: Sturbridge
—c. Case Study: Pennsylvania
—d. Case Study: Maine (again)
VI. So is tolling congestion pricing?
—a. Case Study: Congestion Pricing in Boston?

I. Where tolls do and don’t work
a. Where tolls work

Tolling roadways is an effective means to collect revenue from the use of a resource. In some cases, tolls are pricing a scarce resource, especially where a geographic constraint creates a bottleneck, often with higher-cost infrastructure (in other words, bridges and tunnels). Here, high tolls can be charged for the distance traveled, because the alternative, if it exists, usually requires a significantly longer journey. (The most severe outlier here may be crossing from one peninsula of Michigan to the other: if you ask Google to show you the route from St Ignace to Mackinac City avoiding tolls, it will still send you over the $4 toll bridge, rather than the 900-mile route around Lake Michigan or Huron. $4 is worth it for a pasty.)

In other cases, tolls are used to price a highway serving a major transportation axis with no easy roadway alternative. These tolls rarely use pricing to change demand, although there are some cases where tolls are higher at peak times to move demand away from the busiest periods. For roads which predate the Interstate Highway System, the first mover effect means that these roads acquired a natural monopoly to major transportation corridors and effectively rendered any competition moot (although there are some examples of where an untolled roadway parallels a tolled one), even though the roads may not be near capacity. 

Public policy means that these roads are usually, but not always, tolled below a revenue maximizing level (often, a revenue-maximizing toll would push traffic onto local, slower alternatives, which would be politically unpopular and create additional congestion). In many cases, the tolls are required to be spent only on the roadway itself, to pay off construction bonds and then to maintain the roadway. This had led to tolls which have dropped considerably since their implementation, as bonds were paid off. Even the Pennsylvania Turnpike, which is the most expensive long-distance roadway in the country, has seen its tolls drop since it opened, when adjusted for inflation.


OpenedTollAdj infCurrentChange
NY Thruway1960$5.60$64.02$26.29*-59%
Maine1947$0.50$7.79$2.95**-62%
Massachusetts1964$2.95$31.98$5.95-81%
Pennsylvania1940$1.50$36.15$21.98-31%

All tolls for in-state EZPass users, cash significantly higher (although still generally lower than historic tolls, although not Pennsylvania).
* Average of eastbound and westbound including one-way Tappan Zee toll.
** As little as $1.77 with 40+ transactions per month; original 1947 segment to Portland.

Tolls work best when they toll a section of highway with no reasonable alternative (or when the best alternative is a parallel transit line). If you’re going from Oakland to San Francisco, you can pay an $8.50 toll for a 10 mile trip, drive 80 miles and lose an hour of your life (or often quite a bit more) and pay for 70 miles of additional fuel, or take BART. When San Francisco went from a flat toll to a time-variable toll, some drivers shifted their trips to pay the lower rate (which should not surprise us, but given what we will see later, probably surprised some toll planners), and some probably shifted to transit (although the paper noted did not calculate that difference). 

Longer distance toll roads also make sense, as long as there aren’t parallel alternatives. The history of toll roads in the United States, aside from the 1800s turnpikes (which were quickly superseded by railroads) dates to the 1940s and 1950s, when, before significant federal investment, states would float bonds to build highways across the state. The first long-distance toll roads opened just before the war (the Merritt Parkway in 1938 and the Pennsylvania Turnpike in 1940) and were the models for states to build roads along their main demand corridors before there was national coordination (and sometimes no coordination; Kansas’s Turnpike ended in a field in Oklahoma for a time). The Federal-Aid Highway Act of 1956, which established 90% funding for the Interstate Highway system, all but ended toll road construction for a generation. Toll roads already built were grandfathered into the Interstate system (and states can earn credits for roads which provide a public good but don’t use with federal funding).

Suburban toll roads can be successful (at least in the sense of paying back their construction costs), although they may not start out as profit centers. SH130 outside of Austin was the butt of many jokes and the southern, privately-developed portion did underperform in early years and go through a bankruptcy, but increasing congestion on the free alternative and development along the tollway has led to an increase in traffic (albeit at a relatively high toll rate of about $20 for 90 miles). E470 in Colorado was lightly utilized until a new airport opened, and that, plus development, has made for a profitable roadway. There have been several toll roads in Southern California which have filled perceived gaps in the transportation network, or created sprawl. Or both. (And this is just the United States; many other countries have tolled roads as well.)

Over a long distance, having a limited access highway can save travelers significant time and make a toll worthwhile, as long as there is no free alternative. Chicago to Pittsburgh adds two hours avoiding tolls. From suburban Boston to Albany, where the Turnpike is the only reasonably-fast roadway through the topography of Western Mass, the $4.25 toll (plus a bit in New York) is a small price to pay for a trip nearly twice as fast.

Pennsylvania is an interesting case in the middle. From Pittsburgh to Philadelphia, avoiding the tolls adds more than an hour to a five-hour trip, and most drivers (although certainly not all) will pay the high toll to avoid the longer route. For the first 30 years of its operation, the Turnpike captured much of the east-west traffic in the state, although when the free I-80 opened, it siphoned traffic off not only by providing a faster route, but one without tolls.

 I-80 was originally planned to be built as a toll road, but once the interstate highway act was passed, the lure of “free” money from the federal government was too high, and the road was built using federal funds. Act 44 of 2007 required the Turnpike to make payments to fund other roadway and transit projects, anticipating participation in a federal pilot program to allow tolling of interstate highways. Tolling I-80 would have spread the toll burden across both east-west roadways (which have similar traffic volumes) and kept toll rates relatively low, while eliminating the free “shortcut” across the northern part of the state. 

Because of lobbying from certain parts of the state, the Federal Highway Administration disallowed the tolls, but the state had already planned for this revenue. This forced the Turnpike to take out bonds to pay the Act 44 funds (since reduced) and the toll for the Turnpike has become one of the highest in the world, a $62 for the full roadway, or close to 20 cents per mile, making it by far the highest-priced legacy, long-distance toll road in the country, and several times more than most other roadways which generally fall in the 3 to 7 cents per mile range. Even between Pittsburgh and Philadelphia, an untolled alternative only adds a bit more than an hour, so the state probably loses revenue to people bypassing the tolls, who in turn pay with their own time, leading to a loss of utility for everyone.

Select long-distance toll roads in the United States:


DistanceLow tollHigh tollLow mileHigh mile
NH (3/93)44$1.40$4$0.03$0.09
NH (16)33$1.06$3$0.03$0.09
Illinois (88)140$5.10$10.20$0.04$0.07
Maine102$4.02$8$0.04$0.08
Massachusetts134$5.95$11.50$0.04$0.09
NY Thruway495$22.66$39.66$0.05$0.08
Illionis (90)77$3.95$7.90$0.05$0.10
Illinois (Tri-State)84$4.40$8.80$0.05$0.10
Kansas200$11.66$23.32$0.06$0.12
Okla (Will Rogers)88$5.40$10.50$0.06$0.12
Okla (Turner)86$5.40$10.50$0.06$0.12
Ohio239$16$23.50$0.07$0.10
Okla (Indian)105$7.36$16.74$0.07$0.16
Garden State172$12.38$13.20$0.07$0.08
NH (95)17$1.40$4$0.08$0.24
Atlantic City44$4.22$12.98$0.10$0.30
West Virginia* 88$8.81$13.50$0.10$0.15
Indiana156$16.90$16.90$0.11$0.11
New Jersey117$16.41$22$0.14$0.19
Penna NE Ext111$19.44$38.88$0.18$0.35
Penna Tpke355$62.54$119.72$0.18$0.34

* West Virginia has an annual pass available for just $27, which covers use of the toll road for the entire year, its payback is just four trips across the roadway. The West Virginia EZPass is shown for the low rate here, regular road users, regardless of their state, can essentially use the road for free.

b. Where tolls don’t work

Where don’t tolls work?

Where there’s an easily-available substitute good.

My wife’s family lives near Philadelphia, and we too frequently wind up driving (thanks to $300 Amtrak fares) and pay our fair share of tolls along the way (enough that I’ve considered renting a car and paying the “all you can eat” toll transponder daily fee, since I would save quite a bit for a short trip). If traffic allows us to cross the George Washington Bridge going south, the fastest route is usually via the Henry Hudson Parkway, which has a $7 toll for out-of-region EZPass. However, there’s a route via Inwood or via the Major Deegan and Cross Bronx which costs us about 7 minutes, but saves $7. And, yes, I usually take it, increasing my travel time and externalities on city streets because my time is worth less than $60 per hour when driving on a trip for leisure. (And, yes, I should add a NY EZPass to my collection since the toll is less than half; more on that tomfoolery below.) Everyone loses: the MTA loses out on revenue, the City loses because of additional congestion, and I lose my time.

And yet, there are too many toll agencies which seem not to understand this—many of which are new agencies—and wind up with a variety of toll rates and policies which make no economic sense.

II. One-way tolling

Tolls work well on bridges because they are often natural bottlenecks without effective substitute goods. Many bridges like these have one-way tolling, which mostly dates back to when tolls required manual collection and collecting tolls in both directions would significantly increase the cost of collection, with the assumption that the substitute good was so costly that few people would balk at paying double the rate even if it made avoiding the toll more attractive. As long as these tolls are coordinated and there is a major barrier, this works well. For example, there are no untolled options to cross the Hudson River south of Albany, and as you go south, the tolls progressively get higher, but not to the point where there is an incentive to go out of your way to save money except for some edge cases near Albany itself (notably, it’s cheaper to take the untolled I-90 through the city than the New York Thruway around it, but this toll is collected in both directions and is relatively low).

If a tolled roadway only provides a modest time savings, a modest toll can be effective for most users (infrequent users, and those using rental cars, may still wish to avoid it because of additional fees). But implement a toll too close to a substitute good, and the calculus can change.

a. Case Study: the Delaware

One state west, the crossings of the Delaware River are tolled entering Pennsylvania (or Delaware) and free in the other direction, and traffic is balanced between the two directions, since there are no substitute good routes. 

Until Trenton. At this point, the Delaware River Joint Toll Bridge Commission operates “toll-supported” bridges, which are free bridges, generally with weight restrictions, and are supported by toll revenue elsewhere. The first of these, the “Trenton Makes” bridge, is roughly 500 feet upstream from the nearby one-way-toll bridge. Southbound traffic across this bridge (avoiding the toll): 11,907 vehicles per day. Northbound? 2251. 

There is a similar setup in New Hope a few miles upstream, with data for both bridges. The toll bridge has 4200 daily northbound users and 3200 daily southbound users. But we needn’t look far for the balance: the free bridge (I’m sorry, “toll-supported bridge”) in town has 5700 southbound users and 4500 northbound. More than 1000 people per day will go out of their way by 4 minutes to save $2, which makes sense; it’s a rate of $30 per hour. Simply making the toll bidirectional would make the 4 minutes of travel worth just $1, and assuming a linear time value of money, may increase toll revenues by $500 per day, or close to $200,000 per year. (The Bridge Authority could make more money in Trenton as well by taking in more toll revenue from the world with a two-way toll as well.)

b. Case Study: the Dumbarton Bridge

Another example is the Dumbarton Bridge, the southernmost crossing of San Francisco Bay. The Bay Bridge and San Mateo Bridge have one-way tolls, but the only substitute goods for using those bridges are BART and ¯\_(ツ)_/¯, respectively; if you’re driving, you pay the toll rather than going far out of your way. The Dumbarton Bridge is different. Going around the Bay to avoid the toll adds 18 minutes, nearly $30 per hour plus the additional cost of about 15 miles of driving. 

But there are more marginal trips where crossing the bridge might be slightly faster, and the toll is especially punitive. A trip from Newark to the Googleplex is 8 minutes faster via the bridge. A Google engineer is probably willing to pay $64 per hour to save this time, but a Googleplex cook or janitor may instead pay with their time. (Different users have different elasticities.) Again, this is a location where changing the now-electronic toll to a two-way toll would better balance these trips, and reduce the incentive to avoid the toll.

And the data confirm this (at least the data from 2011). 


EastboundWestbound
Bay Bridge123,000125,000
San Mateo Bridge51,00046,000
Dumbarton Bridge49,00031,000

The Bay Bridge, which has basically no substitute good if you wish to drive across the bay, has as many toll-paying trips as untolled. The San Mateo Bridge, where a toll-free substitute is a relatively long drive, there are slightly fewer tolled journeys (53-47). But the Dumbarton Bridge has a 61-39 traffic split between eastbound and westbound traffic! There are something like 18,000 people who take the Dumbarton Bridge eastbound and then find another way in the other direction every day. If a bidirection toll brought half these people back to the bridge, adjusting for lower use on weekends, this would increase toll revenue by $12 million per year! Remember that this doesn’t cost people $12 million more per year, but the additional tollpayers would be saving at least $12 million worth of their time, and paying to take a faster route. 

There may be some edge case spillover from the San Mateo bridge, and it might make sense to make it, and the Bay Bridge, bidirectional tolls as well. It’s rare that I praise MassDOT, but in toll policy, I will do so multiple times. When tolls in Massachusetts were made electronic, the previously one-way bridge-and-tunnel tolls were recalibrated to be bidirectional (unfortunately I have not found any granular-enough data to see if this changed driving behavior). The Bay Area is leaving more than $10 million on the table by sticking to one-way tolls. And, no, people aren’t saving money. They’re paying with their time, and causing additional congestion and pollution from additional miles driven, so the overall cost to the community is even higher.

III. Parallel routes: substitute goods

The Delaware River may have a few untolled crossings parallel to tolled ones, but these at least are not the main crossings, and are weight-restricted and open only to cars. While this leads to incentives where people will use a longer, slower route in one direction to save a toll, there are both historical and political reasons where this makes some sense. But the data are clear: give people a substitute good, and they will use it. For more recent implementations of tolling, was this lesson learned? Rarely.

a. Case Study: Chicago Skyway

The Chicago Skyway is a case where the lesson was learned, eventually. The Skyway was originally built by the City of Chicago (which had the authority to build toll bridges, but not toll roads, so it is officially a bridge with long approach ramps) and never met traffic projects, because it is roughly parallel to an untolled route. The untolled route via I-94 is 6 miles longer and generally 5 to 15 minutes slower depending on traffic, but combined with the Indiana Tollway toll, it costs $15.90 to travel ($6.94 in Indiana, $8.10 in Illinois). Most drivers are willing to save $16 even if it means a somewhat longer trip.

The Skyway underperformed expectations from day one, and the City lost money on the roadway, initial tolls were just 25¢ and were $2 by 2000. In 2004, they found a solution: they sold the road. A multinational consortium bought the roadway and did the only thing they could figure out: they jacked up the price, today it costs $8 for the same trip (even adjusting for inflation, this is almost three times as much). Instead of trying to serve the greatest number of users, they are trying to make money. And they’re failing. I-94 averages nearly 200,000 vehicles per day, while the Skyway sees just 36,000, carrying just 1/6th as much traffic and making it the least busy highway in Chicago by far. In a sense, the private owner has created a bypass of traffic for some commuters, but the substitute good is close enough in geography and time that there is not any price where they can make a profit on the roadway, even if they are charging a revenue-maximizing price. Unlike Chicago’s parking meters, the City got a good up-front deal on the asset, and the owner is stuck with the underperforming roadway.

b. Case Study: Indiana Toll Road

The Indiana Toll Road, which the Skyway flows into, was never a distressed asset like the Skyway. It is the only conceivable route between Ohio and Chicago, and with I-80 and I-90 interlined across the state, the main truck route, with nearly one third of the traffic made up of heavy trucking (which pays a higher toll, and does more damage to the roadway). Cintra-Macquarie (same firm as the Skyway) bought out the toll road in 2005 for $3.8 billion (equivalent to $6 billion today) and, even managing an asset with significantly less competition than the Skyway (although a trip from Chicago to Detroit, while approximately equidistant via the Toll Road or I-94, will almost always use I-94 to avoid the tolls), overpaid and went belly-up. A new consortium has replaced the original one.

Tolls on the road in 1958 ranged from $1.95 for passenger cars ($22.84 adjusted for inflation) to $13.75 ($161) for six-axle trucks. The same tolls today range from $17 to $107, so white they have decreased, they are relatively high compared to other toll roads, and the concession operator will continue to raise rates, although these increases are limited by statute. While the concession has lost money, it does show that tolling a roadway without a direct substitute good is a means to raise capital funding for other projects, in Indiana’s case, these have been mostly used to repair and build roads in other parts of the state. The private sector tends to overpay.

c. Case Study: Louisville

Louisville sits on the south bank of the Ohio River, a wide-enough river that there are only limited crossings. Within 8 miles of the city, there are four roadway bridges which cross the river, two downtown and two more on a circumferential highway further afield (one of which opened within the past decade). The next nearest crossings are more than 30 miles away from the city. The only substitute goods are a bus every 30 to 60 minutes or a bike path across the Big Four Bridge. (Until 2013, the only bike/ped crossing was the sidewalks of the Clark Bridge; the Big Four had been the “Bridge that goes Nowhere” since it was taken out of rail service in 1968, and had no ramps for 40 years, hence the name.) The new highway bridge has a bike/ped facility; given its location in the suburbs, I doubt it is heavily used.

Here are the four bridges, from west to east:

  • Sherman Minton (I-64, 1964, 6 lanes), 5 miles west of Downtown, mostly serving points west of Louisville (untolled), closed for several months in 2011 because of structural deficiencies.
  • George Rogers Clark Bridge (1929, 4 lanes), in Downtown, serving local traffic, parallel to the …
  • Kennedy (1969) and Lincoln (2015) bridges (I-65, 12 lanes), half a mile upstream from the Clark Bridge. Tolled since 2016. Serves north-south traffic into the city from I-65 and from northern suburban areas.
  • Lewis and Clark Bridge (I-265, 2016, 4 lanes), 7 miles east of Downtown. Tolled.

So between 2015 and 2017, the region went from having 16 lanes across the river to 26. And, believe it or not, traffic disappeared. Some have hailed it as an example of tolling and congestion pricing, but, uh, it’s a better example of what happens when you double the capacity of river crossings. (“Just ten more lanes, bro!”) Notably, traffic on the bridge that was doubled in size has fallen by 50%. But overall traffic hasn’t decreased. Instead, it’s shifted to the free or more convenient alternatives, one of which, the older Clark Bridge, is all but adjacent to the newly-tolled bridge. (The new toll bridge further east of the city doesn’t really have a substitute good, since it reduces the distances traveled for its users by enough that they are unlikely to seek a free alternative.)

The toll to cross the bridge is $2.68, collected in both directions (half that rate if you cross 40 times per month; we’ll return to this later). Taking the parallel free bridge adds between 4 and 8 minutes to travel times, giving the toll a value of time of $10 to $40 per hour. 

Traffic on the bridge declined from 140,000 vehicles per day to 70,000. Some pay a toll to use the new East End Bridge (the current bridge was the substitute good for this bridge before the East End Bridge was built, since the next nearest bridge would be a 90 minute detour upstream), most of the rest take one of the free bridges, either the parallel one, or, if their trip was roughly equidistant, a slightly longer route to cross the bridge downstream. It’s likely that many of the users of the toll bridge are those who use it frequently enough to get the discount.

I am going to cite this Streetsblog/CityLab article which misinterprets this as successful “congestion pricing” when instead it is rational economic actors seeking an optimal solution. (Fun fact, an early version of this post, before it exploded into way too many case studies, was just going to dunk on this article.) It’s laughably simplistic (i.e. just plain wrong). They looked at data from just the tolled road without looking at the whole system which paints a completely different picture. As we can see, many toll planners seem to have the same grasp of basic economics. They assumed that all of the change came from high elasticity for trips, without the actual conclusion that while trips are not elastic, but the willingness to pay is. You know, since the trips didn’t actually go anywhere.

At least they wrote about it so we can pick on them.

If asked to pay for even a fraction of the cost of providing a road, half of all road users say, “No thanks, I’ll go somewhere else” or not take the trip.

The fact that Louisville residents would rather drive miles out of their way or sit in traffic for an extra 10 or 15 minutes to travel on a “free” road, rather than spend a dollar or two for a faster, more direct trip tells you the very low value that highway users attach to these extremely expensive roadways.

Yet this is not the case. People will still make the trip. They’ll just make it differently. Congestion pricing will reduce some trips in a city like New York, where the toll is high, unavoidable and alternatives are plentiful. In Louisville, people will just take another bridge.

Few if any trips take 10 or 15 additional minutes, most are either faster or just slightly slower. These drivers are either going elsewhere and paying a toll on the new bridge, or taking one of the free options. Or they are paying with their time for a slightly longer trip. Very few are actually not making the trip, or using a different mode. Users are generally making rational decisions based on time and costs, they are not reducing their trips entirely. The value is not “very low” but “rational.” Anyone who was making an interstate bridge by driving their $20,000 vehicle several miles each way has a purpose for making the trip and probably values the trip at more than the $2 toll. They just don’t necessarily value their time at $30 to $50 per hour. Economics makes sense.

Data show that traffic on the bridges as a whole dropped by 2% from 2013 to 2018, and has been mostly stable since then, going from 224,000 to 218,000 in ten years, a 2.7% total decline. In Clark County in Indiana, VMT has increased by 2% since 2015, which would suggest a 4.7% decrease on the bridge relative to prevailing regional conditions, but this is mostly due to a 44% increase in commercial VMT; non-commercial VMT has decreased by 3.6%. So relatively speaking, bridge traffic is somewhere between down 4.7% relative to local conditions to up 1.6%; averaging the two to 1.5% may be a reasonable estimate given that most of the new commercial traffic is likely local deliveries which are not using the interstate bridges.

This shouldn’t have been a surprise. When tolls were implemented in Norfolk, Virginia in 2013, a significant chunk of traffic moved to parallel bridges. The total number of vehicles crossing didn’t change, but where they were crossing did. This case study was also not in a location where additional road space was added, nor where there was a directly parallel free bridge. 

I’m not about to run an economic analysis of how the changes in traffic compare to before the bridges, tolls, new bridges which may have increased trip demand and other factors, but will go out on a limb and say that tolling did not reduce trip demand by 50%; Of the 140,000 people using the trip, about 30,000 were given a faster, if tolled, new option, and most of the rest took the parallel, untolled option. Maybe a few dozen took the bus.

These drivers are making a very rational decision because they value their time at $40 per hour which, under most conditions, means that it is “cheaper” to take the free alternative even if it takes longer since the value of time for transportation is only about $20 per hour. The real question is who the drivers left on the tolled bridge actually are. Some probably make the trip frequently enough to pay the lower toll, others have higher values of their time, still others are infrequent users who would pay a higher rate (and for whom the detour is even more lucrative). This doesn’t however, indicate that Louisvillians are somehow irrational actors driving far out of their way, but instead rational actors attempting to avoid paying a toll valued more than their time.

The two states spent $1 billion doubling the size of I-65, only to have half as many people use the bridge. That money was wasted. Nothing more clearly illustrates the utter folly of highway expansions.

But the same number of people cross the river, which is the outcome of having bridges. They’re just making a calculation of how much their time is worth given the options available. If the toll was spread across all four bridges (in which case it could be cut in half since it would be paid by twice as many users) I very much doubt we’d see a 50% decrease in traffic. It would more likely be close to zero, unless the toll were much higher. 

I do agree that this money was likely wasted given the oversized bridges, but it doesn’t have to do entirely with highway expansions. The East End Crossing made the difference, shifting a lot of this traffic. Having the parallel Clark bridge, even one that might become congested, took care of most of the rest. This does not make the argument for congestion pricing, but does show that, given a reasonably-priced alternative, people will adapt to it. And they have, more so than pre-project expectations. Traffic is very slightly lower overall, but it’s hard to say whether that is because of the tolling reducing trips, or overall changes in travel behavior. The East End Bridge would have been enough, without spending billions on a new bridge to add many more lanes.

In any case, it’s a clear case of toll policy setters refusing to talk to an economist.

(The answer of “why can’t they just toll every bridge” is fair, and probably comes down to federal funding issues: the tolls could only be used for bridges which were built using the toll money, even if the bridges otherwise act as a system and are almost perfect substitute goods for each other. No, this is not a rational policy. And while the tolls may be the best deal that the state can get to fund the bridges, it’s not congestion pricing if it doubles the number of lanes and creates congestion on an older, narrower bridge.)

d. Case Study: Oregon

The bridges across the river into Oregon from Vancouver, Washington are somewhat similar to the Ohio crossings near Louisville. Oregon may try to take the same approach as Louisville, although it may be a bit more compatible with creating congestion pricing. Like Louisville, Portland is bordered to the north by the Columbia River which is almost the exact same size (by average annual discharge) as the Ohio (the Columbia is a bit wider). Here there are really only two bridges, the Interstate Bridge (I-5) and the newer (1977)  I-205 Bridge further east. Neither is tolled.

The Interstate Bridge is old. The older span dates to 1917, and it was paralleled in 1958. Each is three lanes wide, and it is the only mainline interstate bridge with a movable span for ships to pass. The bridge was tolled in the 1960s to pay off expenses from this expansion. Given the age of the bridge, it needs to be replaced, and plans are underway to do so, with a price tag reaching well above $10 billion, which will include four lanes in each direction and light rail tracks. The span, which predates the Interstate system, will be tolled starting in 2028 in order to raise funds for this. 

The bridge carries about 140,000 vehicles per day, so each $1 toll rate will raise about $50 million in annual revenue. Even with a $5 toll each way, this is far less than the bridge will cost to replace. And a toll set too high will drive more people to use the free alternative on I-205, a few miles east, although it may discourage some traffic from coming through downtown Portland. That said, a high-enough toll may move enough traffic off of I-5 that the Rose Quarter high project could be precluded or at least slimmed down, especially if better transit were eventually offered across the bridge. While less egregious compared to the Louisville example, it still seems like a missed opportunity to toll both crossings in a way which raises enough revenue and reduces traffic enough to act as congestion pricing. It will raise a significant portion of the revenue needed for the new bridge, but the availability of a parallel bridge means that the revenue maximizing toll is relatively low.

But people think that tolls will eliminate a third of traffic. Let’s just say that this is … unlikely. (High enough tolls may shift a lot of this traffic to a different route, though.) People will continue making the trip. A few may shift to buses. Most will probably shift to the other bridge. For someone making trip from Vancouver to Portland (or the airport) a relatively low toll will not cause them to not make the trip at all. Most will either pay the toll ($5 is a small portion of, for example, the cost to park at the airport and fly to another city, and there is no airport nearly in Washington, and only a small portion of the average hourly wage someone may make by commuting across the river) or pay with their time on 205. If the toll is set to $20, a Chicago Skyway situation will develop: most people will opt for the untolled parallel option, even if it’s longer.

e. Case Study: Vancouver

Let’s journey north of the border to find out another example. In Vancouver (British Columbia, this time), the crossings of the Fraser River were mostly free until around 2010, when two bridges (one new, one rebuilt) with tolls were put into operation. What happened? Traffic on the tolled bridges did not meet expectations, while traffic on parallel bridges increased. When tolls were removed, the traffic returned to equilibrium. Traffic on the newly-untolled bridges increased, while traffic on parallel bridges declined. Far from the Streetsblog argument that people do not place value on their trips, people are willing to pay for their trip if it makes the trip significantly faster. But when it doesn’t, they’ll find a free alternative. And if tolls seem arbitrary and punitive, eventually people will be willing to pay higher overall taxes to remove them altogether.

(Really, someone with the time and training could take all of these examples and run a regression to find out how much drivers value their time. You’d think the toll concessionaires would hire someone with an economics degree to do this before blowing billions of dollars on toll roads with substitutes.)

f. Case Study: Bay City, Michigan

Perhaps the most ridiculous toll scheme is the privatization of two of the bridges in Bay City, Michigan. Never heard of Bay City? Hold up your hand. Point to the “first dorsal web space” between your thumb and index finger. Now you know where Bay City is. As to why it has toll bridges, well, that’s a longer answer where I can’t just point to my hand.

Bay City is spread across the two banks of the Saginaw River where it empties into Saginaw Bay. In a three mile span of the river, there are four bridges. The two northern bridges are owned by the city, the two southern ones are owned by the state. The city-owned bridges needed tens of millions of dollars of repair, and without the funds to repair the bridges, the city leased them out for 75 years with the stipulation that United Bridge Partners to rebuild them and then levy a toll to cover the upfront costs.

I have many questions about United Bridge Partners, which is part of a private equity fund investing in transportation projects which seems to have looked at Cintra Macquarie and said “well, that’s an intriguing business model, what if we did it worse?” They have a portfolio of bridges where they either buy a distressed asset to toll it or build a new bridge the public wasn’t going to build, but they seem to mostly buy bridges which don’t have much of a market. Their bridge ownership ranges from “sure, why not” to “I can not comprehend how this makes any sense.” 

In the first category we have 

  • The Houbolt Bridge in Illinois, which connects I-80 to major rail-truck intermodal yards, and truck drivers and logistics companies may be much more willing to pay $8 to save a few minutes or miles. 
  • The Dominion Bridge in Virginia, where the City got them to build a $345 million new bridge for a $1 toll on a relatively high-demand route, when alternate routes add about 8 minutes of travel time, so most people will pay the toll.

In the second category:

  • The South Norfolk-Jordan Bridge in Virginia has closer replacement goods, and is underperforming with only a fraction of previous traffic (parallel to the previously-mentioned Norfolk bridges, but closer to the replacement good bridge). 
  • The Memorial Bridge between Ohio and Parkersburg, West Virginia, another case where there is a small market for toll users. Parkersburg is a city where the population has declined by 50%, and the city was planning to tear down the mostly redundant bridge, until the private equity showed up. 
  • The Cline Avenue Bridge in Indiana. This bridge, also IN-912, was originally a multilane highway bridge which had severe corrosion and was demolished between 2009 and 2013. The state put out a bid for a private operator, and UBP built a new, two-lane, undivided highway in the same location, at a cost of well over $150 million, as a private, tolled roadway.
  • Bay City …

In the later category, it seems to be no path for them to ever recoup these costs. On the Cline Bridge, UBP says that it services over 1 million crossings per year, which sounds like a big number, with a $2.90 toll for each. That’s about 3000 per day (a lightly-used rural road) or 10% of the traffic of the old bridge (and one third of their expected traffic). The toll on the parallel Indiana toll road is less expensive, and the untolled surface options for local traffic only add a couple of minutes. The business model seems to be based on truck traffic (which creates additional maintenance issues) but the question is quite open as to whether the company has any hope to recoup its investment with a parallel roadway nearby. But still, to finance a $140 million investment, they won’t even come close to repaying the interest at 3000 vehicles per day especially given parallel alternatives.

Their lesson from Cline and Jordan to them was to … do something similar in Bay City. There, two tolled crossings are easily replaced by free crossings which add just a couple of minutes for most users, and while they are currently free for in-city residents, that discount will disappear in 2028. Plus it’s not a huge market: Bay City has about 30,000 people and the population has dropped by 50% since its peak (so the 14 lanes across the river should be plenty). 

The 30,000 people in Bay City are angry about the tolls, and are proposing to boycott the toll bridges—and they should! For most users, a different route will only add a few minutes, and it’s quite possible that a well-publicized boycott could reduce traffic on these bridges close to zero, and if so, good for them. (Maybe some people will even take to walking or biking across the tolled bridges, which is free.) At some point, basic economics has to come into play. And while there has been some additional traffic along the free bridges, there should be capacity for the community to stick it to private equity and, potentially, force their hand into selling back the asset at a loss. (I’d imagine the community putting up homemade detour signs warning everyone off the bridges.) Power to the people! Don’t let private equity get you down.

So, good for Bay City, which is just the latest example of a city government fleecing a private equity toll group which failed to hire an economist.

IV. Volume discounts, in-state discounts, marginal rates and the commerce clause

Many toll agencies have discounts for in-state users, others only discriminate between EZPass users and those requiring an invoice from a plate (some don’t; I see you, Pennsylvania, and I appreciate you). Louisville and Maine have gone one step further and each taken the same harebrained approach to frequent travelers: if you take a certain number of trips, all of your trips for the month are discounted. (Hello! Marginal rates would like a word.)

a. Case Study: Louisville (again)

Crossing the Ohio, that magic number is 40. If you take 39 trips, you pay $104.52. If you take 40, you pay $53.60. Anywhere near 40 trips and you have a strong incentive to make several loops of the bridge to cut your bill. For example, someone crossing 34 times per month ($91.12) would only have to make 3 round-trips (about 30 minutes) to save $37, or $74 per hour. We already know that a lot of people value their time at less than that. 

(How many people do this? I’m not sure, but I have freedom of information requests out to both agencies to see if I can find out.)

The idea is that 40 trips gives regular commuters a break. Which is on its own reasonably bad policy (encouraging driving), but even worse because of the implementation. Given remote work, vacations and holidays, there are probably significant numbers of people who wind up in the 30-40 trips per month range and are incentivized to push it up to 40 to get the discount. This is an economic loss for the agency and for the user, who is forced to spend time circling the bridge to reach the required number of trips. I’d imagine if I tried to sketch the deadweight loss on a surplus/loss diagram, I’d want jam the pencil into my temple instead.

The problem is that the American driver (and apparently toll policymaker) is, by and large, a moron, and has the same understanding of toll rates that Kelsey Plum has of marginal tax rates. A sensible policy would be to apply some sort of discount to additional trips beyond a certain level, say, 10% after 10 trips, 20% after 20, etc, or even 1% for each trip taken, which would decrease the marginal cost of each trip without any weird incentives. But that, apparently, is too difficult for the American driver’s mind, and certain the average toll agency’s policy group, to grasp.

b. Case study: Maine

Maine has a similar scheme: a 20% discount after 20 trips, 40% after 40 (beyond a significant discount for using an in-state transponder, which is why I now have three transponders in various faraday bags in my glove box). What’s interesting about Maine’s system is that by entering and exiting in Wells, Kennebunk and Biddeford, you can trigger four toll transactions without paying an additional penny and with only minimal additional time (a couple of minutes per transaction). For a driver trying to hit an arbitrary trip cutoff, it makes it easy to trigger. 

In Maine, the volume discount is only available for in-state accounts, so outsiders and vacationers pay the higher fees, even when they use an out-of-state EZPass. Notably, the 40 trip discount is per account, so I am working with family to get all of our Maine trips onto one account, since we may well hit 40 transactions per month (especially with some creative trips on and off at the same exit to increase our transaction count). Down the road, New Hampshire will double its tolls next year, but only on out-of-staters. The $2 Hampton Toll—where 70% of transactions are out-of-staters—will go to $4, while in-staters, or those with an in-state EZPass, will pay just $1.20. Which means, yes, I’ll be fumbling between EZPass transponders and faraday bags as I make this trip. (I should really create a device which houses multiple EZPass transponders against the windshield and shifts the faraday block between them.)

But wait! Is this legal? Is this not an infringement of the commerce clause? If I’m engaged in Interstate Commerce, should I really have my rights trampled if I don’t go out of my way to acquire multiple devices? The courts, unfortunately, say “yes,” although I would argue that their opinion is long-since outdated and the right argument could come to a different conclusion. 

There are two cases here, Doran v Mass Turnpike (and the parallel, subsequent Yerger) and Angus v MTA. The TL;DR seems to be that they fail to establish an undue burden against the toll authorities because a) transponders are available to anyone no matter their state of residence and b) there is no undue burden to “swap and stuff” transponders when crossing state laws. 

The legal test here is the “Pike test” based not on a turnpike but on Pike v Bruce Church and whether a law or policy places an undue burden relative to its local benefits. In Doran, which is the base for subsequent cases, it was found that the “swap and stuff” procedure was not an undue burden for someone using multiple toll agencies, nor was setting up and paying multiple accounts. But Doran was decided early on in electronic tolling in 2003, at a time when Maine used an incompatible system, New Hampshire didn’t have electronic tolls at all, and fewer states had in-state discounts. Today, a commute from Salisbury, Massachusetts to Wells, Maine through New Hampshire would cost more than $1000 per year in additional fees without the swap-and-stuff maneuver. It was also decided at a time when we knew little about distracted driving (no one had a smart phone) and swapping requires taking your eyes off of the road to move the transponders while traveling at a high rate of speed. 

After 23 years, it seems ripe to be retried: the facts have changed. If it were, it could also force the 36 separate tolling agencies in EZPass to come to consolidate operations, IT and billing into a single entity. I’m not sure how much we pay for this sort of unnecessary redundancy, but I’m sure it’s not nothing. (Alas, I’m not holding my breath.)

c. Case study: Massachusetts in-state discounts

There is an interesting case in Massachusetts where some people are given toll discounts which are not available to outsiders: residents of four neighborhoods—Chelsea, the North End, Charlestown and East Boston—are given discounts for the bridges and tunnels starting and ending in their neighborhoods. Since these facilities predate federal highway funding and are tolled, the state can give these residents lower tolls for the crossings. 

On the one hand, giving a discount to local users in areas with good alternatives (the Blue Line and 111 bus, which provide frequent transit service) seems like questionable policy. On the other hand, it is, in a sense, redistributing toll funds from the users of the roadway to the communities affected by the roadway, albeit in a sort of backwards manner. There are significant externalities to having a major highway cut through an urban area, this allows the people most affected by the externalities to use the roadway at a discount. Of course, a better policy may be to give these residents discounted transit passes or improve the quality of transit service, rather than give drivers a discount.

By expanding the concept, some amount of road pricing could be returned to the communities through which the road passes to compensate the community for the negative externality. Perhaps communities could decide how the funds were best distributed, whether through toll discounts, a cash rebate to residents, discounted or free transit passes, improved transit service, or some other mechanism. Residents of these neighborhoods do not get such a choice, and instead the only beneficiaries are people who drive, even if many households in the neighborhoods don’t drive (or even own cars, especially in the North End).

One idea would be to establish some sort of “community impact fee” for all highways in a jurisdiction, charging a small price for each mile driven (perhaps as little as 1 to 2 cents per mile). More than a third of vehicle miles traveled take place on major highways which concentrates externalities in specific neighborhoods, and some portion of this road pricing could then be returned to cities and towns based on the traffic volume and the number of people living near the roadway. So a lightly-traveled highway in a rural area would receive a relatively small sum (although perhaps a large amount per capita) while a busy highway through an urban area would receive more (although perhaps the same amount per capita as a busy highway in a more rural area). In Indiana, some of the proceeds of the toll road sale have been returned to the communities. Maybe people would be more amenable to increased tolls if some of the funds were returned to their community.

V. AET, ORT and, uh … why is Maine still building toll booths?

Maine doesn’t just stop with bad toll policy. They’re building bad toll infrastructure, too. We’ve seen what happens when toll booths are eliminated but backwards toll policy remains. But Maine takes it to the next level: they have backwards toll policy and are doubling down on outdated, expensive infrastructure.

More praise for MassDOT, when they went to full all-electronic tolling in 2016, they were the first major toll road in the country to do away with tolls (several newer roadways had opened with electronic tolling) and many others have done this since. MassDOT was somehow on the leading edge of toll infrastructure (they have to be on the leading edge of something, I guess).

But some states still build toll booths. This costs more to build, more to maintain, pose a significant safety risk, and can then wind up creating additional traffic congestion. How’s that for a lose-lose-lose-lose?

A note on safety: this has been known since toll booths first popped up. Lane changes, speed changes, physical barriers: none of these are good. Tolls in Connecticut were removed in part because of a horrific accident at a toll plaza. It did not help that Connecticut’s toll road was unique in that rather than being built with infrequent exits and toll booths mostly on the slower exit ramps, it was tolled entirely by mainline toll booths across the entire roadway. The NTSB has faulted toll booths in deadly accidents like this one, but there is no legislation or policy to encourage adoption of electronic tolling, like creating a unified billing system, mandating RFID chips in license plates for toll payment and detection (maybe some privacy issues there, maybe we could chip plates and ban flock cameras) or requiring states to report on scofflaw drivers who avoid tolls out-of-state. This last point is especially fraught; even states with EZPass can’t seem to agree, and states lose millions of dollars to out-of-state toll scofflaws who don’t pay tolls in other states. As this article shows, a Pennsylvania driver may use an EZPass in their own state, but then remove it and rack up pay-by-plate tolls elsewhere, knowing there would be little mechanism to enforce the tolls in their home state. As usual, toll policy makes no sense.

a. Case Study: New Hampshire

Before Maine kept building toll booths, New Hampshire was the first to screw up open road tolling (ORT), and not by policy, but by physical geometry. Their experiment in open road tolling was hailed as the future when it was implemented in 2010, and it was, in theory, better than the previous state of a 23-lane toll booth with EZPass lanes on either side and cones which could be adjusted for volume in the middle. (New Hampshire was late to the EZPass party, too, not joining until 2006, with the half-price, unadvertised tokens available for 50 years before then.) Prognosticators hailed it as “a miracle of modern technology” and “completely state-of-the-art” installed by people who “were very concerned about these legendary backups.” (In this case, the prognosticator was the Boston Globe’s now-editor, Brian McGrory, around the time he was hating on bikes. So, wrong.)

One problem, Brian: they didn’t actually solve the backups, and the open road tolling made it worse. 

Some terminology before we go further: Open Road Tolling (ORT) versus All-Electronic Tolling (AET). The former has untolled through lanes flanked by toll booths. The latter has a gantry across the entire roadway with photographs used for vehicles without transponders. ORT is more expensive to install, operate and maintain, less safe, and the only benefit is that you can still take cash, so you don’t have to bill people without transponders. 

For a later implementation, New Hampshire would commission a report to study the difference between ORT and AET and the conclusion was that “AET yields positive net revenue compared to ORT in virtually every scenario” (Page 48), not to mention environmental concerns of a larger footprint for toll booths and safety improvements without merges and slowdowns. The caveat is that this is in relation to a “clean slate” implementation, where either an AET or ORT would need to be built, since AET is significantly less expensive, like at the Hampton Tolls nearby. However, it is clear that any toll agency moving from a toll booth system to something else should choose AET.

So converting the Hampton tolls to an AET system now may not have a positive payback given the infrastructure required (it certainly would have been better had it been implemented initially). But the question is whether the Hampton Tolls are actually a completely state-of-the-art miracle of modern technology. It turns out, traffic winds up moving faster through the cash lanes on busy days. One state official said that “it’s seasonal and as a prior DOT employee once told him, ‘You don’t build a church for Easter Sunday.’” The problem is that, to stretch this analogy, they have a church built for Easter Sunday, but didn’t build enough doors.

The issue for New Hampshire is not that they overbuilt the road, but instead that they wildly underbuilt the toll plaza through lanes. Designing an ORT system in the late 2000s, when there was significantly less-precise toll photography, is defensible. Designing one where only 50% of the roadway is dedicated to the open-road tolls is not. The congestion occurs because if the roadway is near capacity, and more than 50% of the transactions want to use EZPass, it creates a completely unnecessary bottleneck. There are other implementations of ORT where the roadway doesn’t narrow and the toll booths are off to the side (which can still induce congestion as people move across the roadway to reach the desired lanes). But to build a too-narrow roadway, and do so without the ability to easily widen it, is ridiculous. At this point, 90% of transactions are electronic, to the point where even at major toll booths the state leaves them unstaffed overnight and uses photo tolling for the few users without a transponder.

A further issue is the location of the toll plaza between two major highway merges. Seven miles north of the Hampton Tolls, the roadway splits into the Spaulding Turnpike north into New Hampshire and I-95 across the bridge to Maine. Seven miles to the south the road splits I-95 south to Boston and I-495 southwest to Lawrence, Lowell and Worcester. The four-lane Turnpike feeds into five lanes going north, and six going south. In theory, traffic should be relatively free-flowing on the four-lane section of the road, since it will have to merge from higher capacity roadways upstream. But the multiple sorting locations along the roadway cause significant congestion.

When the toll plaza was simply two dozen booths spread across the highway, there was no need for drivers to move back and forth across to find a desired lane. Motorists had 14 miles between the Spaulding Turnpike and 495 to filter across the roadway. For instance, someone coming from Maine to 495 would need to move from the left to the right, and someone coming from the Spaulding to 95 would move from right to left. This does create some congestion, especially when traffic is added from Route 101 (especially in the afternoon of summer days when the beaches empty), but EZPass made it worse, and ORT worse still.

When it was originally implemented, the EZPass lanes were placed in two banks so that for each direction of travel, EZPass users would not have to shift to one side of the road or the other. ORT moved EZPass users to the center of the roadway, meaning that many users now have to cross the roadway twice in the 14 mile stretch between merging and diverging. This doubles the number of what I call “sorts” and halves the distance between them. Even if the ORT lanes were widened to accommodate additional traffic, simply requiring people to move back and forth across the roadway creates traffic.

With the state set to double the toll for cash (and out-of-state transponders: reminder that anyone can get an in-state transponder), meaning even more users will move away from cash (and, hopefully, to NH transponders, to stick it to them). This will only exacerbate the issue at the Hampton Tolls. Maybe the additional revenue will allow the state to convert it to a full gantry system once and for all, moving the merge-and-sort back to one sort in 14 miles.

b. Case Study: Sturbridge

Even good AET can not make up for roadway deficiency. On Easter in 2009, a toll-taker shortage created an 8 mile backup on the Mass Pike approaching Sturbridge. Rather than waive tolls to increase throughput, the Turnpike authority elected to continue to collect tolls, and the backup ensued. Yet even with changes in policy and, a few years later, the elimination of the toll booths entirely, backups at Sturbridge still routinely occur in both directions.

Going eastbound, the backups make sense. The roadway is fed by the three-lane I-84 from Hartford and the two-lane Turnpike and feeds into three lanes. In other words: 3 + 2 = 3. (Well, really, 2 + 2 = 3; the onramp from 84 to the Turnpike is a bottleneck but still feeds more traffic into the main roadway than there is capacity.) If the upstream supply is anywhere near capacity, the system will break down.

But going Westbound, we wouldn’t intrinsically expect the same traffic, but it can be worse. Three westbound lanes feed into a two-lane onramp to Sturbridge and eventually the three-lane I-84, and the two-lane Turnpike westbound. In this case, 3 – 2 = 2, which should leave enough capacity, right? 

If only it were that simple. One issue is that there is more demand towards Hartford than Springfield, approximately 60% of traffic exits in Sturbridge to go south towards Connecticut and New York City. But the roadway is three lanes wide, and ⅗ is less than ⅔, so this should be manageable. The larger issue is that the majority of traffic has to sort itself into the two right-most lanes to make the exit, and when the roadway is near capacity, this perturbation can cause delays which send the roadway over capacity and cause congestion, which then builds a traffic jam. This is exacerbated by the nearby Charlton service plaza, where entering traffic needs to move across the roadway to stay on the mainline (at least the highest demand is to keep right). 

This is a case where “just one more lane, bro” might actually make a difference, a fourth lane from the service plaza west, and most importantly a third lane on the exit ramp to I-84, could alleviate some of this congestion. The current configuration of the roadway going west is two lanes to stay on I-90 and two onto I-84, while the traffic split is 60/40. Expanding the ramp would allow the lane assignments from left to right to be 90–90/84– 84–84, better allocating the lanes for the traffic demand. (Going east is harder, a third lane on the ramp would necessitate a firth lane on the main line and an eventual merge, although allowing I-84 traffic to maintain a higher speed on the steep uphill past the interchange, where trucks accelerate slowly, may also help.)

c. Case Study: Pennsylvania

The change from cash to electronics did seem to come quickly, and agencies struggled to adapt at varying rates. For many years, the Pennsylvania Turnpike had a toll booth just east of the Delaware River Bridge. In 2016, with a connection to I-95 finally underway (this was a decades-long ordeal) and would mean that drivers coming off the bridge would have to enter the ticketed toll road, and then immediately exit onto 95. This would mean, for some drivers, three toll booths in about 10 miles: one to exit the New Jersey Turnpike, another to cross the bridge and enter the Pennsylvania Turnpike, and then yet another to exit onto I-95. (There are, or at least were, a lot of double booths near state lines; one to take payment for completing one state and the next to give a ticket for the next state. As far as I know, no states ever combined the facilities into one where the toll-taker would process one state’s transaction and give out a ticket for the next, because that would make too much sense.)

So the Delaware Bridge management (equally the Pennsylvania and New Jersey turnpikes, different from the earlier Delaware Bridge toll authority) decided instead to go electronic. But they still needed to give out tickets and retrieve tolls from the rest of the Turnpike, so they built an entirely new toll booth a few miles away which opened in 2016, the same year Massachusetts was removing all of its toll booths. The cost? $85 million, not much less than Massachusetts’s full conversion. This toll booth was in operation for less than four years. The pandemic led the state to shift more quickly to all-electronic tolling, and it quickly became permanent. It’s one eerie to drive through a brand-new, and mostly abandoned, toll facility.

d. Case Study: Maine (again)

So given all of this information, toll agencies wouldn’t set out to build new ORT in 2025, would they?

Let’s go one state north from New Hampshire to Maine to find out.

Maine’s first foray into open road tolling was the New Gloucester toll booth which gives us another example of how people value their time. A trip on the Turnpike takes about 8 minutes less than using the parallel Route 100, and at the time of a Maine Turnpike-commissioned study, cost $1.25 less (with a Maine EZPass, the highway is somewhat less expensive now, especially for frequent users). At the time, the $9.37 per hour savings (about $12 today) was enough for about 10 percent of drivers to take the longer route around the toll. 

The toll booth there was replaced with ORT in 2013, and ORT was, at the time, somewhat defensible, in a sense because the sensing for license plate images was not as good as it is today. (It also doesn’t cause traffic backups like in New Hampshire because the AADT of the roadway is only about 10,000, so volume is never high enough to cause issues, even with a single through lane.) Maine’s main toll booth in York, like the castle in Monty Python, was sinking into a swamp. It needed to be replaced and relocated. New Hampshire knew that replacing a toll booth with anything but AET did not make sense.

With the current information and analyses of toll infrastructure clearly favoring AET, what did Maine choose for its more recent implementations? They went with ORT. They had a study to back this decision up, and it is quite possibly the most questionable such study I’ve seen (and I’ve read a bunch of, uh, interesting studies—that’s a Midwest “interesting” for those paying attention). It makes the assumption that since one third of vehicles at the York tolls are from out-of-state, they will have trouble recouping unpaid tolls, and there will be little incentive for infrequent drivers to switch to EZPass just to save time in Maine. This leaves out not just reciprocity with New Hampshire and Massachusetts, but that nearly every user of the York tolls will have already had to pay a toll on the adjacent roadway in New Hampshire, and most coming from Massachusetts or further would pay tolls in those states as well. And 90% of New Hampshire toll users are using EZPass, so this assumption is just completely wrong, since it is, for all intents and purposes, the same road. This creates an assumption of a very high proportion of “leakage” of unpaid tolls.

The study notes that in order to recoup this leakage, they would need to add a $3 surcharge to cash tolls, which would push more drivers to the parallel roadway, suggesting that something like 40% of cash-paying traffic would choose a different route if the surcharge were applied. Yet this seems unreasonable. As we saw earlier, about 10% of people will skip a toll if it costs them $10 per hour. Their $6 toll here would compare with $1.50 to enter the highway upstream in Kennebunk, a $4.50 differential, but even under the best of conditions this would cost about 15 minutes, although with traffic on Route 1, it’s often closer to 20 to 30. So under the best of conditions, this would be $14 per hour, under typical conditions, $10.50 and when Route 1 is particularly busy more like $7. Yet their analysis assumed that 40% of people would make this decision, which would add to congestion and travel time on Route 1. There is no citation given for this, the consultants seemed to make the number up. (Consulting: getting paid the big bucks to make numbers up!) And even with AET having a better NPV, the state squinted at the study and went with ORT.

They didn’t fool everyone. Nearby residents pushed the state to adopt AET, but the state refused to do so, and in 2021 opened a new, $39 million ORT toll booth. Within a year it was clear that it was obsolete. From the end of this article is Turnpike Authority chair Peter Mills attempting to save face:

Mills disagrees that the new plaza will become obsolete that quickly. Even if it stops accepting cash, cash lanes can still collect electronic tolls. That provides a crucial stopgap if there is a malfunction of the mainline electronic tolling lanes, he said.

Last year, vehicles were routed through the cash lanes at the New Gloucester toll plaza because of damage to underground sensors in the electronic lanes.

“If our lanes all went down for some period of time, that is a financial casualty of the first order,” Mills said. “Having an extra lane here and there is trivial if it provides the protection we need.”

(Obligatory note that Peter Mills, a Republican, is the sister of Governor Janet Mills, a Democrat. Maine is weird.)

The state spent $40 million to build a white elephant, and is now justifying that decision by saying “well if the toll gantries malfunction, we can force everyone through these auxiliary lanes, which happened once somewhere else. I’ve driven through this toll booth recently, with a constant stream of traffic in the through lanes and not a single vehicle at the toll booths. What a waste. (Maine continues to build ramp toll booths. ¯\_(ツ)_/¯)

VI. So is tolling congestion pricing?

No … and yes.

There are prerequisites for congestion charging, which include high congestion, good transit alternatives, and a relatively compact, contiguous area. Bay City may create congestion, but it’s not congestion pricing. The Pennsylvania and Jersey Turnpikes may have high tolls, but they’re not pricing congestion.

Congestion charges are basically a toll spread across a boundary. Depending on the geography of a city, these can be easy to implement, or considerably more difficult. A high enough congestion charge at a porous border would have a host of issues. Applying it only to highways would push traffic onto local roads through neighborhoods. Applying it in an area with significant local vehicle traffic would arbitrarily charge these local trips. (One critique of Manhattan’s successful congestion charge is that it arbitrarily tolls a trip from 66th Street to 56th Street but not 71st street, which is easily refuted by “there is really no reason to be driving from 66th Street to anywhere, and if you are, you can probably afford the charge.”)

These are similar to issues with tolling highways, if a congestion fee arbitrarily makes winners and losers or is easy to avoid, then people will avoid it.

  • Stockholm’s congestion area is mostly on a series of islands, and crossing onto the island creates natural boundaries and bottlenecks for tolling. 
  • Manhattan is somewhat similar as an island, although rather than tolling the entirety of Manhattan, a line is drawn at 60th street. Charges will increase to $15 by 2031. Per-trip fees for taxicabs and ride shares are between 75¢ and $1.50.
  • Singapore has more of a toll system, with a series of gantries around the center of the country which doesn’t have significant internal physical boundaries. There is a maximum charge of $8 for foreign vehicles, local vehicles pay a distance-based fee based on satellite surveillance. Göteborg and Oslo have similar systems
  • London’s charging zone has the fewest natural boundaries, Milan is also relatively porous. New York’s congestion zone covers about 9 square miles and has about 18 roadways entering, since most of the boundary is made up of rivers with few crossings. London’s is only slightly larger (about 11 square miles) but has several hundred entrances. This sort of system requires a dense enough core with good enough transit that there are few local road trips which are affected. London and New York have significantly higher charges than other cities as well, although London has only about one tenth as many trips as New York, which raises by far the most revenue.
CityArea (sqmi)Charge (day max)Vehicles/day
Stockholm12$1-$5 / $13100,000
New York9$9*500,000
London11$2440,000
Milan3.2$8.5081,000
GöteborgNo defined boundary$7**28,000
SingaporeNo defined boundary$8**300,000

* Will increase in coming years.
** Maximum charge within a defined time period, lower charges if only some toll gantries or waypoints are passed.

If we look at the United States, there are only a few cities where congestion pricing would be feasible, i.e. where there is good-enough transit and a high-density area with high demand. (In other cities, like Atlanta or Los Angeles, it would be more akin to road pricing since demand is more spread out and there are fewer non-car alternatives.) Each may have to rely on a different model if it were to implement congestion pricing.

  • San Francisco already has tolled bridges from two approaches with significant geographic features to the third (San Bruno Mountain), a New York-style system would work, although this would not necessarily help as much with local traffic congestion in the city itself.
  • Chicago is laid out on a grid and has no bottleneck features. A Chicago-Halsted-Roosevelt zone would have several dozen crossings, and a high-enough fee might see people parking or being dropped off just outside the zone. A Singapore-style system, with lower tolls on outlying expressways, might make more sense.
  • Boston is sort of a hybrid of Chicago and San Francisco. Like London, it has a web of roadways with a river through the center of the most congested area, but unlike London, it has highways through the downtown area, some of which are tolled, and some of which aren’t. The untolled highways pass through relatively large geographic features (namely the parks they were pushed through in the 1950s) and tolling these roadways, and potentially some subset of river crossings, would generate considerable revenue, even if the charges were not particularly high.
  • Washington, D.C. has a large network of roads and some natural boundaries, with fewer highways through the city.

There are two main benefits of congestion pricing. One is, obviously, to reduce congestion, which has been observed where it has been implemented. The other is to raise revenue. Congestion pricing need not be revenue-maximizing to be effective: a revenue-maximizing scheme may raise more revenue, but may not be politically feasible. For a city like Boston, a relatively low toll similar to Stockholm, which ranges from $1 to $4.50 based on the time of day, may be plenty to generate revenue to improve the transit system parallel to congested roadways, even if the charges only have a marginal effect on roadway congestion.

a. Case Study: Congestion Pricing in Boston?

Relatively low tolls still have high effects, although this likely has do more to raising revenue than to reducing congestion. We’ve explored many of the pitfalls of poor toll policy and bad economics, so how could congestion pricing be implemented in a city like Boston? 

In Boston, there are about 300,000 tolled trips into the city per day (on the Turnpike and the harbor bridge and tunnel) and about 400,000 untolled highway trips on I-93 north and south of the city. Two cordons could capture most of these untolled trips. A southern cordon could run along the Neponset River, through Milton and across the Blue Hills (with perhaps a portion of Milton where a driver would have to cross two lines so as not to penalize local traffic, even if most Miltonites could afford it) and another spanning the Middlesex Fells. (The Department of Conservation and Recreation, which originally gave up the land for these highways, should also toll its own roads, which run through parkland along the Charles River; the busiest of which—when it’s not decapitating trucks—provides a free alternative to the tolled Turnpike. The cash-strapped agency could solve its budget problems overnight.)

What about the border tolls proposed by ex-MassDOT Secretary in 2024? Aside from being odd optics, it’s bad policy, because the border is easy to circumvent. Depending on the highway, circumventing the toll would require between 3 and 7 minutes, so even at a $1 toll, this would mean a value of time of $9 to $20, the higher end of which would mean a lot of diverting traffic. (Avoiding the Fells or Blue Hills/Neponset would cost on the order of 15 to 20 minutes of increased travel time, so $2 to $3 tolls would likely dissuade only a few drivers.) It would also do little to target congestion where it is worst, especially since there is only a minimal viable transit alternative along most of these corridors (and a lot of the traffic crossing the border isn’t going to Boston anyway). Again, we need proposals grounded in economic reality, not in sound bites.

If the congestion charge for passing through the Fells and Blue Hills were set to be equivalent to the Turnpike and bridge tolls and all were adjusted for inflation (tolls haven’t been increased since 2016), it would generate somewhere on the order of $500 million per year. This funding could be funneled towards material improvements to regional transit—full accessibility, grade crossing elimination at busy roadways, electrification, rail improvements for Western Mass—to provide a better alternative to already crowded highways (also a substitute good!). 

It should be noted that tolls on the Turnpike are quite low, and have gotten lower over time. When it opened, a trip from Weston to Boston cost $2.40. Adjusted for inflation, that would be nearly $30 today, yet it costs $4.25. The “extension” from 128 to Boston originally cost 50¢, which would be equivalent to $5.37 today; the current toll is $1.70. So even as traffic has increased, since 2016, toll revenue has only increased by 10%, but adjusted for inflation, revenue is down 22%, or more than $100 million per year.

Raising tolls on the Turnpike is fraught, because state law requires that funds from the Turnpike be used to maintain the Turnpike, so raising tolls to pay for investment parallel mass transit would require a change to statute. Because of this statute, the Turnpike remains one of the cheapest toll roads, per mile, in the country, even if it is one of the only such roads which leads directly into the main city in its state (most other legacy toll roads skirt the main city in the state; the 1965 Turnpike Extension brought the road into the city, for better or worse). 

Massachusetts transportation funding flowchart is already a web of arrows pointing in various different directions. And federal statute gives states wide latitude on how they can deploy their federal transportation funding, especially by “flexing” federal highway funding to cover transit projects or operation. Massachusetts has historically transferred about 3% of its highway funding to transit (at least in recent years). This is in the middle of the pack in comparison to other states, but well behind California (10%) and New Jersey (close to 15%). Congestion pricing would allow these funds to shift around while maintaining funding for aging roads and bridges. With more toll revenue, it would be easier to justify flexing more federal funding to improve transit.

Should we raise tolls on the Turnpike to at least keep up with inflation, especially if we used the surplus to pay for (and leverage potential federal funding for) parallel mass transit improvements? Probably! But there is a political argument that additional tolls on drivers coming from the west (who are mostly Massachusetts residents) while drivers from the north and south (a higher makeup of whom are from New Hampshire and Rhode Island) get a free ride isn’t unfair, or, at least, politically popular.

Road pricing is clearly a reasonably way to raise revenue and change behavior, but is too frequently mangled by policymakers who seem not to understand basic economics. So any such increase and change would likely have to be paired with additional tolling or congestion pricing, and would require a deft politician with an understanding of basic math, something which, alas, is in short supply in the Commonwealth. Massachusetts was a leader in creating a safer tolling system and has mostly avoided the pitfalls of poorly-thought through economic measures. But it is a laggard in using that system to benefit the traveling public.

BU Bridge: an edge case where a bike/ped bridge makes sense

This is mostly a crosspost from Reddit, with some additional links and information. Show up on Tuesday!

On January 6th, MassDOT and the DCR will (probably) propose the following options to for the Reid Overpass on the Cambridge side of the BU Bridge:

  • Rebuilding the bridge
  • Building an at-grade intersection
  • Building a bike/ped bridge to prioritize people walking and biking

LOL JK, MassDOT will not propose the third one.

But they should.

(They’ll probably present half-baked iterations of what was proposed in 2019, see page 45.)

In general, bicycle-pedestrian overpasses are undesirable, because they introduce unnecessary changes in elevation for people walking and biking. But this intersection is a special case: nearly every bicycle and pedestrian user is already climbing or descending to cross the BU Bridge or the Grand Junction railroad to the east (or both), so a bike/ped bridge would not introduce new climb, but instead just move the existing climb.

A bike/ped bridge, coupled with an at-grade intersection, would be a win-win situation for all constituencies. Traffic between Boston and Cambridge is complicated because crossing the Charles requires navigating a natural bottleneck at one of the bridges between the two cities. The BU Bridge is one of the busiest of these bridges, and connects two intersections with suboptimal geometry on each end with little room in between. An at-grade intersection trying to serve all users would require multiple turn lanes, long signal cycles and long waits for bicycles and pedestrians (think the O’Brien Highway-Land Blvd intersection at the east end of Memorial Drive near Lechmere). A vehicle overpass prioritizes the throughput of vehicles and high turning movements mean there are still busy crossings for people walking and biking.

At peak hour, the intersection is used by approximately:

  • 4000 vehicles of which
    • 1500 cross the overpass
    • Of the remaining 2500, more than 1000 turn left or right, most crossing the busy east-west bike/ped path at the foot of the BU Bridge
  • 16 buses, carrying upwards of 500 people
  • 400 people on bicycles
  • 200+ people on foot

MassDOT’s plan will likely include no provisions to improve transit, and people walking and biking still have to contend with heavy traffic flows. The presence of several hundred bicyclists and pedestrians per hour complicates traffic, since frequent light cycles are required to allow relatively safe passage. Any of the state’s options will likely keep these conflicts in play. 

Here’s why a bike/ped overpass would be preferable for each user group:

  • Bicycle/pedestrians would be able to move through the intersection without having to cross multiple lanes of traffic, push buttons to request signals, or wait for lights.
  • Motor vehicles traffic would benefit from reworked roadway geometry which would help to mitigate the narrow, short bridge bottleneck by adding vehicle queue space. Moving the signal at the bottom of the BU Bridge would provide a safer roadway geometry.
  • Transit users on the 47 and CT2 buses would have signal priority allowing buses to bypass the main traffic light, making trips faster and more reliable.
  • Cambridgeport residents would see fewer traffic jams backing up into the neighborhood.
  • Green space would be improved by retaining the existing mature trees in the “oval” of the intersection and by adding trees, green space and stormwater retention in currently-paved areas.
  • Taxpayers (that’s everyone—we should want more efficient projects!) will benefit from a much less expensive bridge.

Case study 1: Hovenring, Eindhoven, Netherlands

In 2012, a busy and complex traffic circle outside of Eindhoven was replaced with an at-grade intersection with bicycle and pedestrian traffic accommodated on a circular bridge overhead, simplifying traffic patterns and improving safety.

Case study 2: Frances Appleton Bridge, Storrow Drive, Boston

In 2018, the Frances Appleton bridge opened adjacent to the Longfellow Bridge, providing a new, wide, accessible overcrossing of Storrow Drive which integrates with the existing landscape and winds through the trees. A similar design could be used at the Reid Overpass area with the overpass winding through the tree canopy above the roadway.

Sketches here show a proposed layout. Here is the full site plan. The legend is as follows:

  • Blue: bike/ped overpass
  • Red: bus lanes
  • Hollow green circles: existing trees
  • Filled green circles: new trees
  • Yellow: bus stops
  • (S): on second view, signal locations

For east-west bike/ped users, the ramp would rise starting at the existing entrance to the Magazine Beach park, allow users to go to or from the BU Bridge, and then extend east at a level to reach the existing Grand Junction bridge. For north-south users, the route would loop onto the connector to near the 640 Memorial Drive building and have two downramp options, one to and from Waverly Street and the other to the existing Memorial Drive right-of-way, which would be narrowed considerably, and then extending towards Pearl Street. The only downside would be for direct access to Brookline Street, where users would have to make a U-turn on Waverly to access Brookline, as there is not enough room to run a ramp down to the Waverly-Brookline intersection. However, given the upslope of Brookline Street and the MIT-owned property to the east, it’s possible that a bike/ped connection to Brookline could extend north across Waverly and join Brookline at Henry Street (this is not shown).

Removing the overpass, this sketch shows the proposed traffic slows. The four smaller (S) symbols on the right show signals which would only be used for transit operations (or the pedestrian crosswalk to a bus stop), and would let the main traffic flow about 90% of the time. The main signal would be to the northeast of the existing “oval.”

  • From the BU Bridge traffic from the single lane from the south would filter either right onto Memorial Drive (this is a heavy traffic movement and would be unimpeded by signals or bike/ped traffic) or left around the oval, where it would have three lanes of queue space so that when the signal is active, it could utilize the full capacity of the roadway.
  • On Memorial Drive in both directions, right turns would be filtered off, with two through lanes at the traffic light. Single left turn lanes would be provided except for a double-left for the heavy demand from Memorial Drive westbound to the BU Bridge south.
  • From Cambridgeport traffic would follow its existing path around the oval, through the traffic light with a left turn lane, and then merge with the right-turning traffic from Memorial Drive to access two lanes on the BU Bridge itself. This would allow more efficient use of the southbound signal phase at the south end of the bridge, where there is currently a single lane—interrupted by frequent pedestrian crossings—feeding minimal queue space, which would alleviate traffic backups in the existing rotary.
  • For Transit, the southbound 47 bus would use a left-side bus lane and cross Cambridgeport-bound traffic at a signal to access a bus stop accessible from 64 Memorial Drive. This could replace the existing bus stop on Granite Street, allowing a left-side bus-and-left-turn only lane to bypass additional queues. Buses would then proceed though two transit signals to allow them to merge into BU bridge traffic going south. The northbound 47 would use one of these transit signals to access a mixed-traffic lane from Memorial Drive west to Cambridgeport (a low-volume movement) and a bus stop there. The northbound CT2 would use the general traffic lane, while the southbound CT2 would use a bus lane to bypass the main traffic signal.

Show up on January 6 (next Tuesday) and tell MassDOT that you demand a plan which puts the safety of bicycles and pedestrians first, and that a bridge should be built, but not for cars. And if someone has spiked the bubbles at 10 Park Plaza (or, more likely, their consultant) and DOT shows up with a bike/ped-first plan, make sure they know that the community demands it.

The 2024 eclipse traffic deep dive

In April, I wrote about how the eclipse was a microcosm of larger traffic congestion patterns, and promised that I’d post a follow-up after the event.

It’s been a busy summer, I’ve posted two blog posts, seen the northern lights in Gloucester, traveled Zurich, DC (thrice), Philly, Hawai’i, Wisconsin, Chicago, Minnesota and San Francisco (twice) and had one child (buried the lede), so obviously I now have ample time to write Good Content on the Internet between diaper changes. Or, at least, to compile my traffic report from the eclipse.

Our Story

I’ll start with our eclipse story. My original plan had been the Price Chopper parking lot in Derby, Vermont, which would put us in a good spot to leave the eclipse and beat the wave onto I-91, riding the crest of the wave down I-91 to I-89 (or potentially going “cross-country” on Route 25) and avoiding Franconia Notch’s bottleneck. However, looking at traffic on Sunday and figuring that we might hit too much traffic going north on Monday, we changed plans, instead going further north into Maine where we expected much less traffic. With clouds pushing east to Syracuse, I assumed that Vermont and New Hampshire would be even more overrun with eclipse-hunters from Pennsylvania and New York pushed east, but that Maine would seem far enough away to attract fewer people (with more lanes going north), even though, without traffic, Bangor is only 1:30 further from New York than Burlington. So we traded the potential of long delays for a much more reliable 4:30 to 5:00 drive.

(It turns out that, based on this thread, I was pretty much right.)

We piled six people in my sister’s minivan on Monday morning and set off for the eclipse. We had clear sailing through Maine and were aiming for Greenville to meet a friend at the airfield there (he has a two-seater aircraft and was one of hundreds of aircraft there). We had strong road trip vibes, stocking up with snacks at the Portland Trader Joe’s and gas at a gas station in a small town having their busiest day on record (we asked). We skirted through small towns to Guilford where, following my dad’s directions and against my better judgement, I took what Google Maps was telling him and not the main road, going through Edes Corner and North Guilford to Monson.

Google Maps suggested this route, since with minimal cell service there was no way for it to know the secondary merge at Monson would back this up a mile. Luckily, we were well into totality at this point.

About a mile south of Monson we ground to a halt. Google Maps had suggested this route because it detected some traffic on Route 6 approaching Monson. However, our route had no cell service, and its algorithm, which had never “seen” congestion on the road before, must have assumed that any reports of congestion from users were data errors, so dozens of vehicles (if not more) were funneled onto this road which ended at a stop sign (or a yield, where the main road has priority). Throughout history, this had never been an issue, peak summer traffic counts show this as a 300 vehicle per day lane feeding into a 2000 vehicle per day lane (AADTs of 600 and 4000, although measurements in the summer, so actual AADT is probably lower since traffic volume here is seasonal). But today, with constant traffic on Route 6, the side road leading in stacked up a mile back. I was a bit frustrated with my dad for leading me into something I had told him not to do (we never should have had a map on a phone open but instead been using our DeLorme, which was on the dashboard of every car we saw parked in Monson) but we were in totality, so this transgression was forgiven.

After half an hour on this roadway, we reached Monson, 10 miles (and about 20 eclipse seconds) short of our destination and well into totality, and decided to set up camp with hundreds of others there. (Potentially a stroke of good luck, as the airport in Greenville would have been a few extra seconds of totality, and potentially an extra hour of driving). I repositioned or vehicle for a quick getaway and repositioned our watching party to be across the street from the vehicle for the eclipse.

Thirty minutes before showtime, traffic in the town disappeared. It felt almost apocalyptic as hundreds of people stood in a dimming sun (but still bright above a frozen, snow-covered lake) as the sound of vehicles disappeared and all we heard was the wind, birds, and voices. The eclipse came and went and was well-worth the trip.

Now, it was showtime. My plan was to avoid potential merges and bottlenecks going south towards the highway, hoping to get to I-95 before enough of a wave formed to cause highway slowdowns. This meant avoiding the route through Guilford, and instead taking Maine Route 16 (AADT 400) to 151 (AADT 300) to Athens, and then going straight south from Athens to cross the Kennebec River in Hinckley to Route 201. This route would mostly be avoiding roads with multiple branches funneling into a trunk towards the Interstate, and would in theory have minimal other traffic trying to go in the same direction.

Maine was much easier to get out of than New Hampshire or Vermont because there isn’t a range of mountains between totality and civilization. The bottlenecks are instead major river crossings—in our case, the Kennebec—and small towns with merging traffic. Our route avoided nearly every town, and we crossed the Kennebec on a small bridge which didn’t have a long trunk feeding into it. The plan was set, but with no cell coverage, we had no way to see if there were backups forming anywhere along the route.

Our route was mostly sound, with the potential bottleneck of Athens, population 952. I didn’t worry too much about leaving town, there were two roads entering with very little catchment, and three exiting south. We came in on route 151, and while 150 was a diagonal route with relatively low demand on eclipse day, it was the primary road (AADT 1900) at that merge, and Route 151 backed up. (We had no cell reception; but almost took a route around Athens which would have potentially saved a few minutes, unfortunately, the traffic started after that point)

Once through this merge, we went straight down East Ridge Road (AADT 900) due south to the Kennebec, had no issue crossing Route 2 (an east-west route on a day with north-south traffic) and spent a couple of minutes in traffic crossing the Kennebec before smooth sailing to Portland for dinner and the rest of the trip to Boston. How did everyone else fare? Let’s find out.

Traffic in counts in Vermont

The track of the eclipse was almost perfectly-situated for traffic jams in northern New Hampshire and Maine. The eclipse path was situated in a more east-west orientation across New England, with most viewing areas in or north of the mountains. Given the mountains, this leaves only three main north-south routes in Vermont and two in New Hampshire. In Vermont, Route 7 runs east of Lake Champlain, with some parallel roads further east but with bottlenecks. Further east, I-89 runs north from White River Junction to Montpelier and Burlington, the latter segment in totality running east-west along the line of totality, a good collector for traffic flowing south (but with limited capacity). East of there, I-91 runs along the Connecticut River, with minor roadways (Route 10 and others) on the New Hampshire side. Other roads in Vermont are circuitous and low capacity. New Hampshire has two main north-south roads through the mountains, Franconia Notch and through North Conway (Route 16 and Route 302, with significant bottlenecks there). Unlike the interstates in Vermont, every roadway in New Hampshire has a single travel lane in each direction, even Franconia Notch, which was built as a two-lane parkway after decades of legal wrangling and eventual compromise. This is generally not an issue other than peak foliage weekends in the autumn. And, it turns out, the eclipse.

Vermont has a number of continuous traffic data points which we can use to dig into these data. One of these is on the short portion of I-93 in Vermont between the Connecticut River and St Johnsbury. While this was in totality, it was near the southern edge, so most traffic was continuing north. (I heard one report from people who made it to the southern bit of totality just before the eclipse, watched the eclipse, and were the first on the road back, making it back to Boston in under three hours.)

These charts shows northbound and southbound traffic on the day of the eclipse. Blue lines show northbound traffic (towards the eclipse) with red lines showing southbound traffic (away from it). Dashed lines show the normal traffic for weekdays.

I-89 in Bethel, Vermont is a counter on the north-south portion of the roadway just south of totality. This shows the traffic volume going in and out of Vermont before and after totality. Observations:

  • Some people drove north overnight. Typical overnight traffic bottoms out around 30 vehicles per hour, the day of the eclipse there were about 100 vehicles per hour even between midnight and 4 a.m., when volumes increased.
  • Volumes increased to about 2800 vehicles per hour, which is the capacity of the roadway, dropping around 9 a.m., which was likely due to an accident or other event blocking throughput. 2800 vehicles is the approximate capacity of a two-lane roadway, and about 7 times normal.
  • 15-minute traffic counts dropped from 744 between 2:45 and 3:00 to 29 between 3:15 and 3:30, a 26-fold decrease
  • Non-peak traffic was well below normal all day, with about 30% of normal before and after the eclipse.
  • Almost immediately after the eclipse, the roadway returned to capacity, but in the other direction, peaking above 3200 between 4 and 5 p.m. Traffic levels decreased somewhat but stayed elevated until nearly midnight when they finally decreased.
  • Overall, this portion of I-89 processed about 48,000 vehicles on eclipse day, four times more than normal.

Our next data point comes from I-91 near the southern border of Vermont, about two hours south of totality (without traffic).

  • As with I-89, traffic was higher than normal overnight and began to pick up around 4 a.m., peaking close to 3000 vehicles per hour (about 8 times normal) until a steep dropoff around 12:15, since if you weren’t through by that point you had little hope of making it to totality (although traffic did remain elevated for another hour).
  • It mostly stayed below average for the afternoon, but only somewhat, before returning to normal.
  • Southbound traffic was elevated the rest of the day, around 2400 per hour. These rates were lower since traffic had been metered at various bottlenecks further north, but the further-south location means that traffic remained elevated until well after midnight.
  • The roadway processed 19,000 vehicles northbound and 21,000 southbound, with a normal of 6000 in each direction.

I-89 in Williston shows traffic in a higher-volume area in totality, where traffic has some commuter patterns in and out of Burlington, with higher northbound traffic in the morning and southbound in the afternoon. It is also well within totality, so significant traffic volume had exited the highway at this point.

  • Here traffic volumes did not begin earlier than normal. Northbound traffic actually was delayed, since it was not commute-based, and rose higher than normal but never reached 2000 vehicles per hour.
  • Southbound traffic was lower than normal all day, as normal commuting patterns did not occur.
  • At eclipse time, traffic fell far below normal. There were just 67 vehicles during the 15 minutes of the eclipse, just 12% of normal. Given that, we can surmise that nearly 90% of people were watching the eclipse!
  • Northbound traffic then spiked but, given that it was in totality, began to drop by 7 p.m. and had fallen to normal by midnight.
  • Here traffic was just about 20% more than normal, since normal traffic near Burlington is higher.

I-93 is the lowest-volume roadway in this dataset, running between the single-lane Franconia Notch and I-91 in St Johnsbury, with only about 5500 vehicles per day.

  • On the day of the eclipse, northbound traffic began to increase around 5:30 in the morning, but never increased above about 1250 vehicles per hour, even though the volume of a two-lane roadway is double this. This is because Franconia Notch, about 20 miles south, metered traffic into a single lane, so there was no way for any more traffic to enter the roadway, and some of the traffic through the notch was exiting onto other roads in New Hampshire.
  • During the eclipse, northbound traffic never fell below normal; these are likely latecomers who missed the eclipse (or watched it from the roadway, as this was on the very edge of totality). Northbound traffic returned to normal not long after.
  • Southbound traffic was normal throughout the day until it began to fall off around 1 p.m. From 2:30 to 3:30, only 97 vehicles passed going southbound, just 40% of normal.
  • After the event, southbound traffic spiked to nearly 2500 vehicles per hour quickly, but then fell off as upstream congestion and bottlenecks (probably mostly the single-lane offramp from I-91 southbound in St J). Volume fell back to half of this level around 5:30 before some bottlenecks cleared and traffic increased further to around 2000 vehicles per hour, which continued until 10 p.m. before falling back towards normal levels (these vehicles ran into a wall of traffic downstream which didn’t clear out until nearly dawn).
  • The roadway processed about 11,000 vehicles northbound and 14,000 southbound. This is significantly lower volume than the other Vermont roadways (although more than four times normal, the highest ratio of these data sets), but because of the bottleneck at Franconia Notch, had the worst traffic.

Estimating the Franconia Notch Queue

When I wasn’t driving and had cell reception, I took screenshots of traffic. Here was the situation at 10 p.m., nearly 7 hours after the eclipse:

By this point traffic had mostly cleared out of the eclipse zone, but was stacked up on roadways flowing south. Some of these delays were bottleneck delays, notably at Franconia Notch where three lanes feed into one, but also approaching Concord where I-89 and I-93 merge. The latter has a minimal backup because of the metering effect of the notch, while I-89 is backed up because of the single-lane ramp onto 93. At 10 p.m. on a Monday there is minimal additional traffic and what traffic there is has already been metered upstream. The delays on the other interstates is mostly due to volume; with enough vehicles any friction (exit and entry ramps, minor collisions or other vehicles on the side of the roadway, curves, slow-moving vehicles) can create waves of congestion that back up; this is akin to rush hour traffic when there are move vehicles on the road than the road can safely process.

The worst traffic by this point was approaching Franconia Notch. I predicted it would be bad, but I’m not sure I knew it would be quite as bad as it wound up. Franconia Notch merges down to a single lane, and has not only two lanes of I-93 feeding it, but also Route 3 from Coos County in New Hampshire merging in just before the notch. We know from the I-93 southbound traffic counter that there were about 12,000 vehicles crossing into New Hampshire between 3:30 and 9:30, or about 2000 per hour. Let’s assume that there were an additional 1000 vehicles per hour entering in New Hampshire. 3000 vehicle per hour would cause some congestion on a two-lane highway. But 3000 vehicles per hour into a system which can only process maybe half that creates an exponentially-growing queue.

I am not qualified to write about queuing theory (but you can read more about it here) but one interesting tidbit is that it’s relatively recently explained; for instance, one of the theorems of queuing theory is Little’s Law, which is named after someone who died this fall (RIP Little). Queuing theory assumes random arrivals and allows a calculation of a queue length given arrivals and “servers” allowing systems to be optimized to minimize both queue length and overall capacity. So a bank may be okay with having a line which is 10 minutes long 5% of the time (when a bunch of people arrive) if it means they don’t have an additional teller who is idle most of the day. Or a traffic department may be okay with a two lane roadway if the third lane would only be required 30 minutes per day (although usually they’re happy to build the third lane).

For our purposes, it is important to know that when there are more arrivals than servers, the queue grows exponentially. This is why when there’s a major snowstorm, airline call center times can be days long: the airlines don’t have the ability to expand their staffing levels to meet demand, and once the system is over capacity, new people stack in line faster than they can be processed. In this case, a line of traffic formed north of Franconia Notch.

Let’s assume the Notch (plus the alternate route though Kinsman Notch, on a curvy mountain road with stop signs at the end, which also backed up) can process 1800 vehicles per hour. And let’s assume that the demand for the Notch is 1.8 times the traffic demand from 93 in Vermont. (This is based on reports and twitters that the queue cleared around 3:30 a.m.) We can use this to estimate the queue as follows:

This shows the queue growing quickly after the event, slowing slightly before resuming growth, and reaching a maximum length of about 10,000 vehicles after 9 p.m. before arrivals fell below departures and the queue emptied out. Someone arriving at 9:30 would spend 5.5 hours in the queue crawling forward as vehicles were processed out before getting to the notch and resuming free-flow travel south of the notch (and would have already been in other queues if they’d started out from, say, Newport). This may be an underestimate, as some reports were of 12 to 14 hour trips from Northern Vermont to Boston, although additional delay may have accrued elsewhere: 4:30 p.m. leaving Newport, 9:00 p.m. getting to Littleton, 2:30 a.m. getting through the Notch, 4:30 a.m. getting to Boston. 10,000 vehicles across three lanes (two lanes of 93 plus Route 3) would be about a 15 mile backup, which is about what was observed on 93 and Route 3: back to Littleton and Twin Mountain.

People on Twitter and in the news asked two questions of NHDOT: why did they close exits onto Route 18 and why didn’t they reverse the northbound lanes in the Notch. The first of these is easy: it just would have moved the bottleneck, since it didn’t create new lanes through the Notch (Kinsman Notch was just as bad). The queues may have been shorter, but they would have moved slower. (This is why widening a highway without fixing a bottleneck doesn’t work, and also why lane diets like those on the Longfellow and Harvard bridges between Boston and Cambridge do: the bottlenecks aren’t due to the number of lanes on the bridges; reducing the number of lanes increases the length of the queue, but the queue moves faster.)

The second is a bit harder, but I’d guess that no one really knew how bad it would be and if they had, they would have come up with a plan. They would have needed a northbound detour, and given the mountainous roads nearby, this would have to be communicated dozens of miles south for larger vehicles (at least Plymouth via Route 25, if not Concord), which would have to have been established in time for the end of the event and run all evening. One lane of traffic could have exited at the north end of the Notch at Route 18, crossed under, and run southbound, before running south on Route 3 several miles to reenter I-93 at exit 33. Given the maneuver on and off of the highway and people switching lanes, the capacity probably would not have been a full lane of traffic, and long queues (although maybe not as long) would still have occurred.

Kinsman Notch was so bad that if I zoomed out all the way on my phone to try to show it, the traffic would go away. Here’s the middle portion.

Other eclipse bottlenecks

I took screenshots of traffic all day (and the day before and after, see this hashtag on mastodon; I’ll mirror most of these below). These images show traffic the day of the event. There were usual holiday-weekend bottlenecks in Concord and Franconia Notch around 8 a.m., which were getting worse by 10 a.m.

Note: to view these images larger, right-click and open in a new tab. At some point, I will change them to link automatically, figuring out how to do that right now.

There were also some backups on other roads leading north, along 87 and 91.

Bottlenecks formed in other places not used to them, including Lancaster and Gorham in New Hampshire. Sugarloaf saw traffic based on a busy ski day in April, also anomalous, especially for a Monday (Sugarloaf and Saddleback were sold out months in advance, and wound up having perfect spring skiing conditions). Quebec City is north of totality, so everyone was clogging the bridge to get south.

There was additional traffic elsewhere, including Northeast Pennsylvania, Nashville, Ohio and Detroit.

Here’s Columbus, Cincy, Montreal (more traffic than typical trying to get across the bridge; Montreal was on the edge of totality so people were trying to get to more darkness) and then where the Autoroute from Trois-Rivieres dumps onto the main Quebec-Montreal highway.

Then the Eclipse happened.

And minutes after, the drive home, although I didn’t have cell reception until after 5 p.m. By that time there were long backups on highways which never see them, and even on I-95 north of Bangor, a portion of highway so sparsely traveled they only built a dual-lane carriageway in 1982. There were long queues on 89, 91 and 93 in Vermont and New Hampshire, with bottlenecks forming where demand outstripped capacity.

By 8 p.m. traffic had spread out from the center line across the country (and Canada). Most anywhere with a bottleneck or a demand corridor had a backup.

By 10:30 p.m. I was back at a desktop and had changed my background. If we’d gone to Vermont, I might still be in traffic in Franconia Notch. 93 was back to Littleton, Route 3 to Twin Mountain; Kinsman Notch was jammed, too. Google Maps had eventually figured out that people should go down 89 and cut across the un-jammed Route 25 (or even further south) to avoid the bottlenecks. That had been my plan had we gone to Vermont: get south of the notch and take Route 25 (but there was actually an even better plan, see below).

Not everyone got stuck in traffic on Monday. Some people stayed put and got stuck in traffic midday on Tuesday. (Less traffic, but still not normal.)

How did some people avoid traffic?

What was the best strategy to see the eclipse and avoid traffic? Go diagonally across the demand lines. In New England, the demand to see the eclipse ran almost entirely north-south along major highways. It then spilled over onto secondary and tertiary roads (Kinsman Notch, for example, and some smaller roads in Vermont and elsewhere). But if you managed to find a route which connected the eclipse path to somewhere which was more sparsely populated, you could get home from the eclipse without seeing much in the way of tail lights. Here are two examples.

The Champlain Valley in Vermont to Boston. Middlebury was right near the edge of totality, but even a few miles north would have been in totality without hitting the worst traffic. This would have worked from Burlington as well. Rather than get onto 89 and sit in hours of traffic, the diagonal route, nearly entirely on back roads outside of totality and not crossing through any bottleneck points (in fact, not using an Interstate highway at all) took about 4:30, according to a friend who did just this from Middlebury and hit no traffic. Even with some traffic on Route 7 to get to Midd, this would have been far preferable to hours on I-89.

Newport, Vermont to Boston is normally a three hour trip but on eclipse day was 8 or more (unless you were the first car out of town). But if you were to drive east far enough and then drop diagonally through Maine, you’d avoid the demand lines and would have made the five hour drive with minimal traffic, through Dixville Notch in New Hampshire and Grafton Notch in Maine before picking up the Maine Turnpike home. In both cases, you would have enjoyed a beautiful drive as well.

What about trains?

Some people mentioned: what if we had reasonable passenger rail lines which could have taken people to the eclipse? If we did have a robust rail service to these low-population areas, it still would have required significant capacity to move the requisite number of people. For a sporting event, there is a finite number of people needing transportation from a fixed point, even a large stadium only needs 50,000 people, and these are usually traveling a short distance (within a city). Here, millions of people need to to be moved hundreds of miles to multiple locations (maybe if we had a European-style rail network we could have mustered every rail car on the East Coast to run trains to Burlington).

Because the trains can only reasonably satisfy one trip given the time it takes to get to and from a population center, even with vastly improved infrastructure, rail lines would only have so much utility). The New York City subway has about 5000 cars in service at peak hour, with capacity for about 800,000 people. But on a busy weekday, 6 million people rode the system, nearly 8 times the instantaneous capacity. But if everyone in New York decided to take a subway trip at the same time, the system would be overwhelmed. (It’s why serving outlying stadium events is logistically difficult.)

A note on EVs

Some people drove their electric vehicles to watch the eclipse, using up most of their range to travel 200 miles. On the way home, they attempted to recharge, only to find that there were very few chargers of any kind, and the fast ones were, let’s just say, oversubscribed. Now to be fair, the family described in the article probably would have just sat in traffic had they gotten recharged faster. But the experience shows the scalability of high energy density fuels (gasoline) versus lower-density batteries and has some corollary to the pitfalls of electrifying transit fleets and charging them centrally.

Most of the time, the low number of chargers in rural New England doesn’t matter. Most local drivers charge at home, other users don’t overwhelm infrastructure. And pumps don’t really function the same way as gas stations. Gas stations have almost limitless capacity with the energy stored on-site. Rural stations usually have a few pumps, which are rarely oversubscribed, and if they are the queue moves fast enough because fuel can be moved quickly. Gas pumps can run at up to 10 gallons per minute, so a Prius can get 500 miles of range in 50 seconds, while a less-efficient vehicle may take up to 2 or 3 minutes (plus a minute or two to begin and end the transaction. On average, it’s probably about 3 minutes per 500 miles, or 10,000 miles per pump hour. A small, rural gas station with four pumps could push our 40,000 miles of range over the course of an hour, and doubling the pumps to 8 (many are this size) could get 80,000 miles with minimal additional infrastructure. Over 10 hours, 8 pumps would probably run down much of the capacity of a gas station, but during that time it would service 2000 vehicles (as far as I can tell, no gas stations ran out of gas, even if anecdotally one we stopped at in Maine had their busiest day on record). Gas stations probably had to schedule additional tanker dropoffs after the eclipse, but other than that, there were no knock-on effects.

Meanwhile the fastest EV charger can run at about 250kW. This is a lot of power, and charging 100kW, enough for about 300 miles of range under ideal conditions, would only take about 24 minutes. But this is only a rate, with transaction time, of about 650 miles per charger per hour; to reach the capacity of an eight-pump gas station would require about 120 charging stations. Even if the stations were scalable, bringing enough power into the installation would be a challenge: this would require 30MW of power, enough power for a town of about 25,000 people. The cost to bring in that much power would be untenable for a once-in-a-lifetime event, which is why many EV drivers were stuck. In the long run, it would take a significant build out of electric infrastructure equal the scalability that gas stations already have. So EV drivers faced the queue before the queue, waiting hours to recharge.

Solar signals

Staying in the realm of electricity, we can look at how the New England power market responded to the eclipse. On the left below is the demand for a normal, sunny spring day in New England, in this case, for the day after the eclipse. The orange line shows actual demand, the yellow line shows demand including behind-the-meter solar (mostly rooftop). This illustrates the “duck curve” well, with a huge dip in midday power generation need thanks to massive solar installation; at midday more than 6GW of the 14GW in the ISO were being generated by behind-the-meter (in addition to this, industrial-scale solar puts out another 700+ MW). On the right is the day of the eclipse: it paralleled a normal day but at eclipse time, there was only about 1.2 GW of behind-the-meter solar, about 1/4 of normal (this is estimated, actually may be even less). While totality only crossed a small swath of New England, most of the rest of the region was under 90% or more reduction in sunlight. Not visible to the naked eye, but certainly to a solar panel.

Here are charts of industrial-scale solar (the y-axes are different because the output from the ISO app is different based on other resources, sorry). Eclipse day was normal until about 2:30 when it went down to almost zero, before bouncing back for the rest of the afternoon.

Finally, we can look at the electricity resources and real-time prices for eclipse day. For resources, you can see the spike in natural gas (the light blue line mostly at the top; the steady orange line is nuclear) and imports (the darker blue line at the bottom, which was negative most of the day since New England, with excess power, was mostly exporting). There was also an earlier bump in hydro than usual to account for the eclipse (hydro is the middle blue line, which was steady around 1GW since this was during the spring freshet and dams across the region were running high; by fall, run-of-river baseline hydro is below 300MW). Note a minimal change in renewables; the spikes in other resources were making up mostly for behind-the-meter solar, which doesn’t show up as much in the chart.

There was also a price hike. Prices during early afternoon were below $0, with lots of solar and wind the region needed to incentivize power to be cut back or exported to keep the system from overloading (this is somewhat typical on cool, breezy, sunny days in New England). Demand also dropped (which can be noted on the charts above) for the hour before and after the eclipse; people unplugged enough to reduce draw on the system when half of the region was staring at the sky. Once the eclipse shadow crossed, prices jumped up to incentivize more production, before falling back to more typical levels the rest of the day.

What did we learn?

If there’s a solar eclipse you can reasonably get to, go. But don’t make plans to fly to a specific location that may be cloudy. Be flexible. Avoid bottlenecks. Consider a longer route which avoids where everyone else is going (but don’t use the obvious backup route: Kinsman Notch was a mess, Route 25 was better, Dixville Notch was fine). Two lane highways have clear capacity constraints, and when a queuing system is over capacity, it takes along time for it to clear.

And there you have it, 5500 words about the great eclipse of 2024.

Measuring airport transit (and why Atlanta is the best and Boston is the worst)

Boston has the worst airport transit in the country (and maybe the world) … at least by a metric I devised below.

Logan airport lies less than two miles from Downtown but under even the best of circumstances a transit trip there can take 25 to 30 minutes (at rush hour, driving can be just as bad). If it wasn’t for the harbor, it would be a pleasant walk; San Diego, the only similarly-close airport in the country, is a nice walk from downtown. But it’s not, and it should be better.

Airport transit can be, and has been, measured in many ways, including:

  • Your boyfriend Nate Silver (This is a reference to Wonkette in … 2008? God I’m old.) looking at transit travel time versus driving and whether it makes sense to take transit just from a time standpoint and Honolulu somehow has faster transit than driving (not until HART opens, if it ever does).
  • The Points Guy who somehow has Boston on the Nice List (it’s close, I guess)
  • CityNerd who uses a similar metric to the one I will, but also doesn’t differentiate based on the distance from the airport, so airports near cities aren’t penalized when they have lousy transit connections (and he also doesn’t do buses, which I get, but they should be included).

My approach is a bit different: I wanted to look at each airport, the typical travel time to “downtown” with half a headway added to penalize infrequency and calculate the “speed” which this is based on a straight-line distance this covers. Most cities only have one airport. Cities with close-in airport transit connections should not get special treatment over those with airports far away with good transit connections, especially since the noise and pollution of having an airport adjacent to dense housing is not great. (This is where I disagree with Ray’s—uh, CityNerd’s—methodology, which was distance-agnostic, although that was one of his earlier videos and he has since moved to often using more complex analyses.) In a sense, my methodology sort of a second derivative of travel time.

So what does it give us? For the 30ish largest airports (I added a couple extras for … fun, or in the case of Pittsburgh, because my wife was taking the 28X when I was drafting this) the speeds range from 25 mph in Denver to an almost literally pedestrian 3.9 mph in Boston (although the pedestrian route would be longer since there’s a bit of ocean in the way, but a fast triathlete could make it faster than taking transit). The speed to get from Boston to its airport is 50% slower than any other airport in the country.

AirportTravel timeHeadway/2DistanceTotal time“Speed”
BOS2261.8283.9
TPA36155515.9
SAN1782.5256.0
FLL20133.5336.4
LAS36155.5516.5
HNL27134.4406.6
BNA32226.8547.6
PDX4186.4497.8
LGA3956448.2
CLT26155.7418.3
PHX1983.8278.4
MIA2585339.1
SLC2585339.1
LAX571511729.2
AUS3686.8449.3
BWI35158509.6
JFK707137710.1
ORL35158.55010.2
EWR5010116011.0
MKE2776.43411.3
DCA1443.41811.3
PHL221573711.4
PIT4115145615.0
MSP2287.53015.0
DTW3038186815.9
DFW5010166016.0
CLE2789.63516.5
MDW2568.63116.6
IAH48815.85616.9
STL311011.84117.3
SEA34511.33917.4
ORD46415.65018.7
SFO304123421.2
IAD566236222.3
ATL1748.42124.0
DEN37818.54524.7

This metric has a flaw, however: there is a significant correlation between distance from city center and speed. It’s not surprising that the two closest cities to their airports, Boston and San Diego, are two of the three worst performers. A longer distance allows more time at speed and less time in congested areas. Similarly, some of the “fastest” connections are some of the furthest. Denver clocks in at 25 mph and while the A Line is a convenient trip, the airport seems halfway to Kansas, and getting there takes a good deal longer than Boston or San Diego.

So I plotted out these data, and took a regression, and figured out what the “speed” “should be” for each airport based on its distance from the city center. (Yes, that’s a lot of quotation marks in on sentence; this is a made-up metric.) Far-out airports should be faster, the trip doesn’t take place entirely near downtown, so trains can move faster over longer distances between stops and buses can benefit from less-congested highways. This gives us an idea of how fast we would expect a trip to be based on the distance traveled, so airports close in aren’t unduly penalized compared with those far away. The R-squared here is about 0.6, and the line slope is 0.85 mph per mile, plus a constant of 5 (which is basically half of a “decent” headway). So an airport 10 miles from a Downtown should have a travel speed of about 13.5 mph, meaning a 45 minute travel time, which seems about right.

Points above the line are better-than-expected service, those below are worse. The point at 4 miles and 11 mph is DCA, the point at 13 miles and 10 mph is JFK. While the speed is about the same, DCA is much easier to get to by transit because we’d expect an airport as distant as JFK to have better transit.

Put this all together, and we can now compute, for each city, how fast we expect a trip to be compared to the actual speed, and then compare this. This adds a couple more columns to the chart but changes the order significantly. Also note that for this run at the data, I’ve added in the four big airports in Canada (Montreal, Toronto, Calgary, Vancouver) and for airports with under-construction links—namely, Montreal and Honolulu—added them in as well (with an *). (LAX also has something under construction, but I’m not sure it will make it any faster to get there, at least from downtown.) This changes the slope of the line slightly and the calculations are based on that slope. I’ve also bolded the airport name if it has an all-rail connection and italicized it the connection is a one-seat ride (nonstop for buses), and, yes, bold-italic shows a one-seat rail trip.

AirportTravel timeHeadway
/2
DistanceTotal time“Speed”Expected “speed”Speed/Expected
BOS2261.8283.97.154%
TPA36155515.99.760%
JFK707137710.116.262%
LAX571511729.214.663%
LAS36155.5516.510.164%
YYC45106.5557.111.065%
BNA32226.8547.611.267%
PDX4186.4497.810.972%
FLL20133.5336.48.575%
EWR5010116011.014.675%
LGA3956448.210.678%
SAN1782.5256.07.778%
DTW3038186815.920.378%
BWI35158509.612.279%
CLT26155.7418.310.381%
ORL35158.55010.212.681%
AUS3686.8449.311.283%
DFW5010166016.018.786%
PIT4115145615.017.088%
IAD566236222.324.491%
IAH48815.85616.918.591%
MIA2585339.19.793%
SLC2585339.19.793%
PHX1983.8278.48.896%
PHL221573711.411.4100%
ORD46415.65018.718.3102%
MKE2776.43411.310.9104%
STL311011.84117.315.3113%
SEA34511.33917.414.9117%
DEN37818.54524.720.7119%
YVR2646.73013.411.1120%
CLE2789.63516.513.5122%
MSP2287.53015.011.8127%
MDW2568.63116.612.7131%
DCA1443.41811.38.4134%
SFO304123421.215.4137%
YYZ25812.33322.415.7143%
YUL*2239.42522.613.3169%
HNL*1234.41517.69.3190%
ATL1748.42124.012.5192%

So Boston is still worst on the list. We’d expect a trip for the two miles between Logan Airport and Downtown Boston to go about 7.5 mph, and for the trip to take about 14 minutes. Instead, it takes twice that. But San Diego is no longer as close to the top of the list, beating out Portland, which has a direct rail connection but, because it takes so long to cover a relatively short distance, is worse, and also EWR and JFK, which have all-rail journeys (albeit with forced transfers).

The best transit, by this metric, is Atlanta, which is just 8.4 miles from downtown but averages 24 mph, nearly double what we’d expect, making the trip in 17 minutes with frequent service. Toronto’s current rail line (the UP Express) and Montreal’s upcoming REM are also high, although Montreal’s will be part of an integrated transit system and not an airport-only route. Honolulu will vault near the top of the list, just shy of Atlanta, when (if?) it opens, and SFO and DCA are both near the top. (For the pedantic, I am counting SFO as a direct trip even if for many airlines you have to take a connecting shuttle system.) Note that DCA is ranked similarly to SFO even though it’s speed is half as fast: we wouldn’t expect such high speeds for such a close airport.

Other than Atlanta, the two fastest domestic airports are DEN and IAD, each in the 22 to 24 mph range. At DIA’s distance, it still outpaces its expected speed. Dulles is, by five miles, the furthest airport from its downtown (if you assign BWI to Baltimore, and FLL to Fort Lauderdale, as I have), and we’d expect its transit link to be faster, but the distance and number of stops mean that even the well-running Silver Line is relatively slow. BWI and PDX are the two worst direct rail links, with slow (and especially in the case of BWI, infrequent) trains even if they are convenient to the terminal.

Only one bus connection exceeds the expected travel time, in Milwaukee (which is one of the additions to this list; the airport doesn’t crack the top 30), the airport has a bus from downtown which runs every 13 to 15 minutes basically 24/7 (with some slightly longer headways—and a one hour gap—in the middle of the night). Notably, it’s not even an airport-specific bus, but just a city bus which serves the airport. Pittsburgh’s 28X doesn’t quite have the span or frequency of Milwaukee, but provides a good service given the airport’s distance from Downtown. IAH is similar, but for an airport its size, the transit service is lacking.

Is Atlanta the best airport transit link in the world? No, but it seems to be close. Zurich and Frankfurt both offer fast, frequent service to nearby airfields, each about five miles away (similar to National, although imagine DCA having a stop on the adjacent rail line with through service from the NEC, MARC and VRE). Arlanda outside Stockholm is an outlier. It’s as far from the city as Dulles, but the in-vehicle travel time is just 22 minutes, compared to 56 for Dulles, operating over a 200 km/h railroad (Oslo’s airport is the same distance and a minute faster, but somewhat less frequent). The mode share for Schipol is 50% transit (and 0% hyperloop)!

Somewhat notably, Asian airports seem to have middling airport rail connections, around the 100% mark (using the US/Canada baseline), while Europe leads the pack. (The chart below shows major airports >180% better than expected travel time; the next best I found—SYD—is just 152%, but I likely missed some.)

AirportTravel timeHeadway
/2
DistanceTotal time“Speed”Expected “speed”Speed/Expected
ZRH11351421.49.7220%
ARN22522.72750.424.1209%
FRA1155.61621.010.2205%
AMS1657.62121.711.9183%
OSL211022.73143.924.1182%

There may be others, but Atlanta, and maybe at some point in the future, Honolulu, certainly seems to hold up against the best airports to get to by transit in the world.

(Here’s the data I put together, if you’re interested.)

And Boston? A fix won’t be cheap. The Silver Line is slow and dumb and prone to tunnel traffic. The Blue Line is a mile from the airport and the buses are … slow and prone to terminal traffic, and a direct link from Downtown quite a bit more expensive. And because the connection is so short, a world-class connection in the 180% range would require a 9 minute trip, including wait time (hello, Zurich). A 100% trip, 15 minutes including the wait, may be more reasonable. An airport people mover would be expensive but could make it in 17 minutes: 4 minute wait, 6 minutes on the Blue Line, 2 minute wait, 5 minutes on a people mover. But for now it remains stuck on the bottom of the list.

The T’s 2024 marathon schedule

[updated with post-race experience in italics]

I’m not running the Boston Marathon this year. It’s not for lack of interest: I ran a 2:59:56 last year, my best finish in Boston (by time) and an improvement of 11 seconds over my previous best (and first) race in 2015. I thought it would be plenty fast to qualify, but the weather was good enough last year (fun fact: with more than 13,000 qualifiers more than 51% of finishers requalified. and it had the single highest number of Boston qualifiers of any race, ever), and new sponsor Bank of America stingy enough (apparently they took more sponsor bibs, so the number of qualifiers accepted was about 1000 fewer than previous years) that I missed out. By 24 seconds. Or, since I am in the final year of an age bracket, by 3 months and change. 

(As you can tell, I am not bitter about this at all. It would be exceedingly petty to hope for temperatures in the low 70s for the race, but it would also mean that the -7:20 qualifier I ran last fall would be almost a shoo-in if Boston had 4000 qualifiers instead of 14,000. I will make no further comment as I check a weather model. But who am I kidding, it will be 48˚, dry, cloudy with a 20 mph tailwind with my luck.) [it wasn’t, so I have a shot next year]

It does mean that I’ve had extra time to look at the T’s somewhat impressive marathon schedule. For the first time since 2019, the T has the resources to provide extra service, and this is on top of a schedule which already has more frequent midday service. With 64 total trains, it is likely the busiest day on the Worcester Line since the 1950s (at a time when they had four tracks to Framingham before the Turnpike cannibalized two). In addition, several trains have been extended to Southborough, making taking the train to the start a much more reasonable proposition. There are basically trains every 20 to 40 minutes in both directions, so spectating runners in three locations is somewhat reasonable. Plus, there’s a $10 all-weekend pass, so you can hop on and off basically for free. (They are undercharging for this; it should be a separate fare for Monday, but they probably don’t want to have to sell more tickets. It’s good for ridership, at least.)

So with no further ado, here is Ari’s Official Guide to the Railways on Marathon Monday. A couple of notes.

  • I use train numbers here preceded with a “P.” At least back in the day, trains on the Worcester Line were numbered with a “P” by CSX designating them as Passenger trains. This naming convention makes the text a bit more readable. Also Dave does this, so it is the right thing to do.
  • Three-digit train numbers (e.g. P518) are normally-scheduled trips. Four-digit numbers (e.g. P7564) are extras or have changed schedules.
  • This all assumes that everything runs on schedule. So, you know, take it with a small grain of salt. [especially after about 10:00, trains experience 15-25 minute delays between Framingham and Wellesley Hills because without level boarding, it takes a lot of time for people to get on and off]
  • In Wellesley, I sometimes refer to the stations as “Square,” “Hills” or “Farms” just so I don’t have to type “Wellesley” so much.

If you want to watch the lead men:

Arrive on any train in Framingham before 10:00. There are trains departing at 10:08 and 10:35. The 10:08 train (P7556) will depart almost exactly when the lead men’s pack arrives; you may be able to watch from the train as you roll out of town (the men may outpace the train for the first few hundred yards). The 10:35 (P7564) train will depart after the lead men (and women) are through and when the first Wave 1 runners begin to arrive.

If you take the 10:08 train, you can get off at Wellesley Square (10:23) or Wellesley Hills (10:26) to catch the lead men, who should arrive at Wellesley Square around 10:31 or 10:32 and Hills a few minutes after. P7564 departs Hills at 10:53 if you want to attempt to catch the runners again. The lead women will probably arrive a few minutes later; train P7514 (11:13) will allow you to comfortably watch the lead women run through. These trains will get you to Lansdowne by 11:17/11:37. The first would allow you to get to Lansdowne in time to see the lead men, the latter unlikely.

(Rosie Ruiz would be proud!)

Speaking of women, if you want to watch the lead women:

Arrive in Framingham by 10:15 (train 7653 arrives 10:14). Train P7564 will depart after the lead pack of women has gone through and get you to Wellesley Hills at 10:53, a couple of minutes before they arrive there. Train P7514 will leave Hills at 11:13, and get you to Lansdowne in time to see the lead women a third time quite easily.

If you want to watch a first-wave runner with a 3:00 or faster (given the depth of this year’s field, the entire first wave qualified under ~3:01).

You will still need to be on train P7563 and arrive in Framingham by 10:14, so you’ll get to see the lead women (get there earlier and you’ll see the lead men, too). Your runner should pass in time to take P7514 inbound at 10:55 and get you to Wellesley Square/Hills at 11:10/11:13. From there, P7516’s departure at 11:45/11:48 will give you plenty of time to get Downtown; even P7568 half an hour later would do the trick if your runner is running slower than a 2:50 or so.

If you want to watch a second-wave runner with a 3:15 finish time:

You’ll want to arrive in Framingham by 10:47 (although, of course, you can get there earlier to watch more) on P7513. Your runner should pass through well before 11:30, allowing you to take train P7516 and get to Wellesley Square with plenty of time to cheer. From there P7568 will get you downtown to see them finish.

The third wave is much more spread out with finish times spanning an hour between 3:25 and 4:25. Here are some scenarios:

3:25 runner: P7565 out arriving Framingham at 11:19 (or earlier, of course). P7568 inbound at 12:05, P518 inbound at 12:55 from the Wellesleys.

4:25 runner: You still probably want to arrive in Framingham by 11:19 as above. Depending on the time to cross the start line and your runner’s speed, they will clear Framingham around noon; if so, you can catch the 12:05. Otherwise the 12:40 train (P518) should get you to Wellesley in time to watch them there; you may want to ride it to Wellesley Farms and jog to the course to get ahead of them. From there, you may wish to walk to Riverside and take the Green Line downtown, although the Green Line is often quite slow on Marathon Monday.

For Wave 4 runners, the finish times are even more spread out. A Wave 4 runner may be a charity runner without a qualifying time and run faster, or an older runner with a slower qualifying time running a 4:50 race or slower. In these cases, consult the schedule.

Are you a runner who wants to skip the buses and take the train out?

I’ve never done this, but with the schedules this year it seems quite reasonable. There is a spectator shuttle from the state park near Southborough to Hopkinton and, apparently, to the Commuter Rail station as well. [There is definitely a shuttle from the Commuter Rail Station!] For spectators this might mean that you could watch the start, take a bus to the train station, and potentially see your runner a fourth time (although taking the bus to Southborough and then the train to Framingham in 40 minutes would be tricky; this might work better for later waves and then only if the timing is perfect, you could at least make it to, like, Natick).

But to get to the race, sure, why not? The “athlete village” at the high school is a glorified port-o-let line; and there are plenty more of these near the start line anyway behind the CVS. You could probably even have someone travel out with you to the start spectator area, take your gear, and see you off. (They could drive you there, too, but where’s the fun in that).

Trains P7507, P7561, P7509 and P511 arrive in Southborough at 8:11, 8:45, 9:12 and 9:53, about 50 minutes from Back Bay (and 40 from Boston Landing). Given the convoluted route the buses have to take to get to the high school, this may actually be faster than taking the bus, especially if getting Downtown would require some backtracking. And you’re not crammed into a bus designed for 6-year-olds worried that the driver is going to get on 495 north and wind up in New Hampshire. (Yes, this happened. In 2022 my bus driver—the bus itself was from Methuen so the driver was not familiar with the area—wound up on 495 north. No one batted an eye, because no one was from the area. I made my way to the front of the bus and guided the driver through the cloverleaf at Route 9 and back south to Hopkinton.)

So would I do it? I’m not entirely sure. [Most assuredly.] I trust the T well enough, but I guess the question would be getting from the T to Hopkinton. If all else fails, it’s a 2.5 mile warm-up run (albeit uphill). [I saw people doing this] I assume the buses would run as advertised and I would bet one could be flagged down on the road from the State Park (if they aren’t running to the train station). [Probably couldn’t flag one down, but definitely could take one from the train station.] It looks like you can get into the corrals from Cedar Street [Yes, you can walk right in, it’s kind of a VIP area with some charter buses parked nearby but they don’t seem to discriminate and/or probably assume you’re special, too.], otherwise from South Street would probably work. I’d leave at least an hour to get from the train to the start, but for a Wave 1 runner, leaving Boston Landing at 7:31 might be far preferable to being on a bus at the Common at 6:45. 

If I get in in 2025, and the T runs the same schedule, my plan is to take the 7:56 train from Boston Landing arriving at 8:45 at Southborough, and get on a bus there to the start. The next train (8:31-9:11) should work fine but having some buffer is nice. The earlier train would give enough time to walk back to the Athlete’s Village but there’s really no need to do that. If the weather is awful and I really don’t want to wait in the rain I might consider taking the bus, since there’s usually somewhere dry to wait at the start. Plenty of johns at the CVS.

Perhaps I’ll have to go out and do some reportage on the transit situation myself. Enjoy the race, and if you’re running, you’re welcome for the weather. [yeah, sorry, no one die at the finish line please]

A few notes:

  • Train numbering convention is that trains running to Worcester begin with 500 and theoretically range up to 549. 550 and up are Framingham turns. Even east, odd west.
  • There’s no express service in the morning. So there’s half the overall frequency of a normal weekday morning, although each station has about the same number of trains, the express trains run local. Service is then redistributed across the midday.
  • Previous marathon special service was basically to keep the normal weekday schedule and add a couple of trains in the middle of the morning. This increases service all day long, on the baseline of already increase service (2019 base schedules had four trains between 9 a.m. and 4 p.m., current schedules have hourly service, and the Marathon service this year has 14 trains in this timeframe, double the 2019 Marathon schedule and the normal 2024 schedule and more than triple 2019’s base schedule).
  • Service has also been extended out to Southborough much of the morning, and then as the race moves east, trains turn in Framingham. This really shows that some thought went into making the schedule.
  • With 63 trains calling at the Wellesleys and at Natick, this will likely be the most trains to stop in Wellesley in the 190 year history of the B&A. There were more trains in 1950, as far as I can tell, but many of them were express and intercity trains (plus, there were still four tracks east of Framingham back then).
  • The current schedule has 66 trains including the Lake Shore. 1952 had 64, 1950 had 68, 1947 had about 80, 1945 had 94, with nearly hourly service to Springfield (better, if you include local trains). Boston to Springfield in 2:10. Even the 1937 schedule, with about 120 trains daily, and the 1927 schedule, with 160 trains per day (!) has less service to Wellesley. (The 1927 schedule had 8 to 10 local trains between Boston and Riverside between 5 and 6 p.m., running subway-level service on that portion of the four-track railroad.)
At its peak, the B&A ran more service than the Marathon Schedule. Except to Wellesley and Natick, they’ll see the most stops ever on Marathon Monday. (This doesn’t even include intercity service. Also note the Saturday-only midday outbound service; this was back when a regular workweek was five weekdays and a half day on Saturday.)

The eclipse and transportation

Subway stations with long escalators usually have three. There are three escalators in Porter Square in Cambridge, and in all (or most) of the long-escalator Metro stations in DC (those don’t have stairs, even). This is mostly so that when one is shut for maintenance, there is redundancy for the others to run. But when all are operational, generally two run up and one runs down.

There’s a good reason for this: escalators are a natural bottleneck, and people arrive at a station pretty much randomly in a steady stream. But people depart stations in clumps: trains arrive and people get off all together. Even still, there can be queuing at bottlenecks where people have to slow down or navigate something which causes them to change their speed. Like getting on or off an escalator (or stairs).

So, there’s an eclipse on Monday. (I promise this is related!)

  • First thing first: the eclipse is totality or nothing. 99.3% = 0%. You have to go into totality, and preferably far enough in that you get more than two minutes of totality.
  • Second thing second: avoid clouds, and don’t plan ahead beyond “eclipse day.” In 2017, my father and I were in Louisville with family. The eclipse path there passed from Missouri to South Carolina, and we were prepared to drive any distance in any direction to see it. Turns out that we were able to go towards our intended destination (Chicago) and it was worth it.
  • Third: You do not need to go to where a bunch of other people go. Or somewhere specific. No matter where you go, if it’s clear, the sky is the sky. (Okay, climbing Mount Mansfield, which isn’t really allowed this time of year anyway because the trails are muddy, might let you watch the eclipse shadow approach over Lake Champlain at 1100 mph, but also is more likely to be in the fog.)
  • Expect spotty cell coverage at best. Rural areas may already be uncovered, but even the towers there might be completely overwhelmed. Pack a map, and snacks.

I’m very excited about seeing the eclipse. It’s a brilliant celestial event which occurs once every few years-if-not-decades with reasonable travel distance, it’s not commercialized, it’s a great communal event. And … I’m almost as excited about seeing what happens to traffic afterwards because this is a once-in-a-lifetime event and we really have no idea how it is going to play out.

Traffic happens because of the intersection of two elements: volume and bottlenecks (in another sense, demand and supply). A lane of traffic has a theoretical throughput of 2400 vehicles per hour, although this is rarely achieved. Once it becomes saturated with traffic, both speed and volume decreases; this process can take place solely based on volume around 1600 vehicles per hour (or a bit higher). Volume drops to 1000 or even less, with low speeds: this is called “Level of Service F.” (Far too often we plan roads around avoiding this by building oversupply rather than trying to manage demand.) Bottlenecks can cause additional queuing, and this isn’t solely lane drops: merges can be just as bad, as can what I call “sorting” where vehicles approaching an exit have to change lanes. Given high enough volume, this can devolve into a traffic jam, even if there is no theoretical loss of roadway supply. Once a road is congested, it requires a drop in demand to become less congested. That may not happen post-eclipse.

In most cases, we have a good idea of how traffic will behave. In urban areas, we see this occur on a daily basis. In more rural areas, there are certain locations which have frequent traffic when city-dwellers (and suburb-dwellers) return from weekend travel. In New England, these are somewhat illustrative:

  • I-95 southbound in New Hampshire traffic is the product of two merges and two sorts. First is the 95-16 merge, a 5-to-4 merge. Then is a sort-and-merge for the Hampton Tolls, which were inexplicably built with only two through lanes of toll booths even though 75% of weekend traffic pays electronically. As people move around and squeeze into these lanes, it causes severe congestion. From there you’d expect that the 4 lanes of traffic feeding into 6 (95 south and 495 south) wouldn’t be congested, but with the toll sorting, traffic then has to re-sort to the two destinations, causing additional congestion. (Northbound traffic, while usually not as bad, also has multiple merges and sorts.)
  • I-93 between Manchester and Concord. While the toll sort here is also problematic, the main issue is the 4-to-3 merge in both directions, with additional traffic streams joining. So again, a merge impacted by a sort.
  • The Cape Cod bridges. 3-to-2 merges, short merge distances, narrow lanes with poor sight lines, etc.
  • The Turnpike at Sturbridge. Eastbound it’s a pretty simple 4-to-3 merge. Outbound it’s theoretically 3-to-4 but the sorting into the exit to 84 often backs up miles. (The 290/395 exit often creates its own traffic jams, sometimes these merge: fun!)
  • I won’t get into Connecticut but the highways there seem to have been planned by looking at a bowl of spaghetti, with left entrances and exits and merges and sorts which will congest in a slight breeze.

Aside from these, and Connecticut, Providence and Boston, there’s just not a lot of traffic in New England. On some fall foliage days, a few single-lane roadways in New Hampshire can have backups of epic proportions, mostly when a town (or even traffic light) lies between a road and a highway: The Kanc, Route 100, Route 16. These are traffic jams that occur a few days per year; a few miles of highway bypass could reduce them, but there’s other reason to do so, especially when some people are going to “do the Kanc” and don’t mind if it takes 4 hours to look at the leaves.

Once these people high the highway, there’s enough capacity for them until they get to a bottleneck closer to home. So we don’t really know how traffic is going to behave with more people on the roads than ever before. We have a sleepy, low-volume subway station and a once-in-a-lifetime event … and we are all taking the escalator.

This is different than Phish: the Vermont traffic jam then was caused by muddy fields which couldn’t be used for parking, and a backup onto the interstate (a mile of traffic only has about 200 vehicles in it; so this was basically a 30-mile-long stationary queue of cars trying to get to a parking lot that didn’t exist, until everyone abandoned their cars and walked to the show). That was caused by everyone trying to get to a single point (that wound up having limited capacity). The eclipse covers thousands of square miles. Many people will get there with time to spare (given how booked-out hotels are, days in advance for some). But once it’s over, it’s over. It’s on a Monday. Everyone is going home. We’ll converge on the same roads. The usual bottlenecks in New Hampshire may see some traffic. But there are new ones further north which have never seen this much traffic.

Vermont doesn’t have many continual traffic counters. There’s one just south of Barre/Montpelier. Peak traffic there is about 1000 vehicles per hour on weekdays, and up to 1500 per hour during peak season (foliage, ski). This is significantly lower than the capacity of a two-lane roadway (3200 to 4000 per hour). The one near Waterbury is similar, there’s a bit more traffic right near Burlington at commute times. These roadways never operate at even 50% capacity. So we have very little idea how they will operate when at or over capacity, particularly when these flows hit downstream bottlenecks.

The AADT (average annual daily traffic) on I-89 ranges in the 20 to 30 thousand range, other area highways are far lower (in New Hampshire, I-93 has an AADT in Franconia Notch of 11,000, and under 7,000 a few miles north in Vermont). During peak summer and foliage weekends, I-91 in Vermont sees as many as 8000 vehicles per day. The busiest stretches of roadway in Boston see that many vehicles per hour in each direction. There are some expectations of 200,000 people going to Vermont for the eclipse. This is a week’s worth of traffic on I-91 and I-89.

So around 3:15 on Monday, or a few minutes after, we’re going to see all sorts of new bottlenecks and people flow onto highways for the trip south. Where will it be worst? Here are my predictions/guesses:

  • I-89 south of Burlington. Burlington traffic will fill the road, which then runs along the south side of the path of totality, so additional traffic in Waterbury and Montpelier will attempt to merge on; and this is a road with relatively high baseline traffic.
  • White River Junction. The ramps here are not designed for peak traffic traffic, although the likely peak demand (89S-91S and 91S-89S) luckily do not overlap.
  • RIP anyone attempting to get from Vermont to New York on Route 7, single lanes and traffic lights do not have particularly high throughput. 87 in New York may not be much better and I wonder what the ferry lines will look like (although it would be a great place to watch the eclipse).
  • Franconia Notch. I-93 looks like an Interstate, but was built to non-Interstate standards through Franconia Notch after various legal wrangling. With 10,000 vehicles per day, the single lane merge never really backs up. With most of the Boston area converging on it at the same time, well, I’ll be avoiding it.

We have some data to go off of from 2017, when there were similar traffic jams around a very similar event. I tweeted out some traffic photos, shown here are people headed out of major population centers (Atlanta and Charlotte) towards the eclipse. And here’s what happens when there’s road construction narrowing a two-lane road down to one (I think the state DOTs have the message this time, it’s also still the season of winter, not construction).

TRB wrote about it, as did some academic articles. There were traffic jams reported across the country, and locations which had high levels of traffic for hours before, and especially after the event. Here’s a GIF of Google Maps traffic. A lot of the worst traffic was reported in places like rural Kentucky, Idaho and Wyoming which for all intents and purposes do not have traffic.

The eclipse passed over Wyoming, but not Colorado. So tens if not hundreds of thousands of Coloradans headed up I-25 to find totality near Casper. There are very few highways in Wyoming, so traffic was funneled onto this singular roadway. Southbound traffic from Wyoming to Colorado jumped 10-fold once the event was over. Backups were reported for the entire rest of the day, and a 4 hour drive wound up taking 10. I-25 is somewhat unique in that there are no local roadways to shoulder some of the load, so while it may not be a direct corollary to Northern New England, this level of delay may not be out of the question. For the most part, reports found traffic was densest after the event.

The weather this year may also concentrate traffic. 2017’s eclipse was mostly in the clear, but this year is going to be mostly cloudy, with only Northern New England and a swath from southern Missouri to Indianapolis in the clear. Both of these share the characteristics that they are near large population centers not in totality: the Northeast Corridor for New England (and potentially parts of upstate New York) and Chicago and Saint Louis (and others), so add to that longer-distance eclipse fans fleeing Texas and Ohio and traffic may get even worse.

Tips for optimizing for traffic? Well, first optimize for visibility. This is a couple-times-in-a-lifetime event. Once you’ve done that, consider getting yourself near the eclipse center line but pointed in the direction you want to wind up. Then get ready for a long ride home. And once I’m home, yes, I’ll scrape some data and analyze it in this space. (I might throw in some Mass Pike Superbowl data, too.)

The construction crew on the Key Bridge saved lives. (Just not that many.)

There have been many, many people on the Internet and elsewhere who have talked about the “many” lives saved by the quick actions of several layers of responders this week to close the Key Bridge to traffic. I’ll pick on Yonah Freemark here (sorry, Yonah), but you can find any number of twitterers talking about how many lives were saved. This guy said “it could have been hundreds” in an otherwise informative interview. The New York Times story about the audio says it “likely saved lives” which, as I’ll explain, is probably better phrasing.

The bridge collapse occurred at 1:30 in the morning. There’s a pretty good chance that, had the mayday call not gone out and had the local authorities not intervened, there would have only been two vehicles on the bridge, or perhaps none. The presence of the construction crew, which was not able to evacuate the bridge, may have been the reason the response was so quick, since there were police vehicles nearby. This leads to two lessons and a thought:

  • Major bridges over busy shipping channels should have means to quickly stop traffic (perhaps even automated gates)
  • Construction crews on such bridges should have good communications and be prepared to quickly evacuate.

The thought is that people vastly overestimate the use of highways at very off-peak times of day. The MTA probably has better data from electronic tolling, but the most recent public traffic count for this bridge seems to be from 2019 (the user interface for Maryland’s traffic counts—like most such interfaces—leaves a lot to be desired). It includes an early Tuesday morning, so it’s probably good enough for a rough estimate. From that, we can find that somewhere around 180 vehicles cross the bridge per hour between 1 and 2 a.m., which would mean that at any given time, there would be approximately 3 vehicles on any given mile of roadway. Since the collapsed portion of the bridge is about 2/3 of a mile long, we would expect there to have been two vehicles on the bridge when it collapsed, right?

Well, kind of. We actually have tools for figuring this out. What’s that music? It … sounds like the entrance music for the Poisson Distribution! The Poisson Distribution is “a discrete probability distribution that expresses the probability of a given number of events occurring in a fixed interval of time if these events occur with a known constant mean rate and independently of the time since the last event.” This is basically how traffic works. (It’s also, for example, how passengers arrive at a transit node.)

We can use the Poisson distribution to find the probability that n vehicles would have been on the collapsed portion of the bridge given the traffic levels. This gives the following:

n = 0: 14%
1: 27%
2: 27%
3: 18%
4: 9%
5: 4%
6: 1%
7 or more: 0.4%

So the modal outcome is (1 or 2) but there’s about the same chance of no cars on the bridge as four or more at that time of day. Given that vehicle occupancy overnight is likely not much more than 1, the number of lives saved by this specific chain of actions is likely in the range of zero to four. If you watch the video, you can see the number of cars on the bridge basically ranges between 0 and 3. As we’d expect. Statistics are fun!

That said, there’s a lot this leaves out. Additional vehicles on a bridge approach could have Thelma-and-Louised off the bridge without warning given driver inattentiveness (although “road” is a major detail). More importantly, having these policies in place means that had this occurred at a higher traffic time of day, it would have prevented a mass casualty event (although it seems like the presence of the work crew may have been part of the reason there were police officials nearby, so we may be very lucky this occurred at 1:30 a.m. and not 5:30 p.m.). Using the Poisson and the peak traffic of 2700 vehicles per hour, there would be a 96% chance of at least 20 vehicles on the span, a 45% chance of at least 30, and a 3% chance of at least 40. (Still, “Hundreds?” Well, Poisson does have a long tail but the probability of that would be quite small.)

Beyond that, there’s an outlier event where the bridge has a traffic jam and vehicles couldn’t clear the bridge with advanced notice. This is why, for example, in the Mont Blanc tunnel, which had a previous mass casualty event, has very specific rules about vehicle separation, and the Tobin Bridge in Boston is closed when an LNG tanker passes underneath. But this roadway had a low-enough traffic count and is far enough from bottlenecks that it’s likely very rare that traffic ever backed up onto the bridge.

There’s also an argument that the ROI for rebuilding the bridge isn’t there for 32,000 vehicles per day (again, thanks, Yonah). Some caveats there. 1) The bridge had $57 million in toll revenue in 2023 ($31 million cars, $26 million commercial vehicles). This is about 8% of the state’s toll revenues, and much of the traffic might move to other tolled facilities. But there would be an overall loss of revenue. 2) The bridge is a haz-mat route and with the other two routes through Baltimore in tunnels, haz-mat would have to detour around the Baltimore Beltway. 3) Would the State of Maryland be able to recover salvage damages from the ship owners and insurers if they chose not to rebuild the bridge? I don’t know, I’m not a lawyer. (Or, for that mattter, a bridge engineer.)

Will such a boat-on-bridge failure happen again? There’s no reason to think it won’t. Ships are getting bigger, and there are only a couple of dozen bridges of this magnitude over waterways with large ships in the country (San Diego, San Francisco and Portland on the West Coast; Houston, New Orleans and Tampa on the Gulf; Jacksonville, Charleston, Chesapeake Bay, Philadelphia, New York and Rhode Island on the Atlantic, plus potentially Boston, Portsmouth, the Penobscot and a couple of canals, although these have much less traffic). In a sense, it already has, and the new Sunshine Skyway has significant deflection infrastructure around it (we just didn’t learn from that disaster). Perhaps this will be a wake-up call to reinforce deflection around vulnerable bridge supports. In the shorter term, large bridge operators should consider having SOP both for bridge users and bridge workers in case of this sort of event.

Early rail designers were just guessing

Recently, Alon asked about the curvature of the MBTA’s Providence Line, which also hosts* Amtrak’s service and has about half of the high-speed rail line in the country. It’s also some of the oldest railroad in the world and the Canton Viaduct is quite possibly the oldest high-speed bridge in the world (barely high speed: 130 mph / 209 km/h), with the bridge dating to 1835 and the rest of the line to 1834. Why is it that the old B&P railroad is suitable for high-speed operation while other railroads are not? It probably is mostly due to luck.

(* “hosts” is a strong word here; the T owns the fee, Amtrak maintains and dispatches the infrastructure and charges the T for this, but the T used to charge Amtrak. This is a whole, uh, thing.)

The first major railroad in the US was in Baltimore, with the Baltimore and Ohio running west along the Patapsco River towards Harper’s Ferry. This route followed the river valley and had numerous sharp curves in the river valley in the 4 to 6 degree range. The railroad was also built on deep granite foundations, much like the Boston and Lowell, as engineers at the time thought that track would be unstable otherwise (it turns out they were dead wrong; track needs some tolerance to move around, which is why today it is mostly laid on ballast). Several other railroads sprang up, mostly from coastal cities, and over a year between 1834 and 1835, three such railroads opened out of Boston, to Providence, Lowell and Worcester.

At this time, when communication between cities took days and across the ocean took weeks or months, there wasn’t much standardization for this new technology. Nothing had moved faster than the speed of a horse up to this point in history, and all of the sudden, large pieces of equipment could move 30 or 40 miles per hour, or faster. No one knew that the rails needed cross ties and not granite support, and no one really seemed to know what kind of curves and grades would be allowable. So, it seems, they guessed.

A note on railway curve measurement. In the US, it is generally expressed in “degrees of curvature” which somewhat paradoxically means “how many degrees of a curve are covered over 100 feet.” (This is a decent shorthand to avoid having to figure out the radius of big circles.) If you think back to trigonometry, a curve has 360˚ in it, so a curve that covers one degree in 100 feet will cover 360˚ in 36,000 feet (about 7 miles) and have a radius of 5730 feet or 1746 meters (the rest of the world often uses curve radius in meters for this). A one degree curve is quite shallow and can support speeds of about 130 mph.

Now, do you use the arc or the chord for this measurement? Generally chords, because the calculations are easier than for arcs (not a lot of pocket calculators in 1832). Highways use arcs. For all but the sharpest curves, the difference is inconsequential. With most mainline railroad track less than 8˚, it doesn’t really matter (it is more of an issue for streetcar track, for instance, Tower 18 on the Chicago L has approximately 70ish degree curves, with an chord of 130′ and an arc of 150′, they use radii).

So the B&O had sharp curves. The Boston railroads were built with fewer, and each company seems to have chosen a standard of sorts. The Boston and Worcester, which had less money than the others for construction and built west through more difficult terrain, was built with a number of curves in the 3˚ to 4˚ range, and many 2˚ or more (so, not really a standard). The Lowell and Providence lines were different: they had greater resources and connected Boston to established mill towns. Railroads at the time didn’t know if they could climb any significant grade, so attempted to avoid hills (they still do). Without any rivers to follow, the B&P and B&L attempted to avoid the glacial hills between their cities and slalomed between them.

For the Boston and Lowell, 2˚ was the measuring stick. The railroad has a number of curves, and nearly all of them measure to almost exactly 2˚, good for about 80 mph (depending on cant deficiency), which is about what the railroad there runs today. I don’t have any definitive information on this, but every major curve on the railroad is just about 2˚, few are less, and none are more. Immediately past Lowell, where the railroad was extended not much later, there is a 5˚ curve: engineers found out trains could make that kind of curve and built it (oh, and there were some expensive factories and a big river in the way).

Providence is similar: it, too, has to run between a number of hills on its way to Providence. The first 10 miles split hills in Boston and then follow the Neponset River, but the river only goes so far and the railroad eventually has to climb. The solution was a grade up to Canton, a bridge across the Canton River (a stream feeding the Neponset) and eventually a straight line from Mansfield to East Providence. The route to Mansfield has a number of curves, including across the Canton Viaduct. Measuring each, they all almost exactly 1˚, a speed good for about 130 mph.

This is the speed the line runs today. While not the highest of high speeds, it means that a trip from Back Bay Station to Providence, a route of 43 miles, takes 30 minutes, including a stop at Route 128 station; without that stop, the average start-to-stop speed would top 100 mph. This also includes the last few miles into Providence, which were built once the B&P realized that sharper curves were possible, so it was built with sharper curves.

The original Providence Station was east of the city, along the Seekonk River. This was suboptimally located for access to the city, and especially for through service (although a now-abandoned tunnel was built in 1909 and could conceivably provide a 3- to 4-minute faster trip between Boston Providence if the right-of-way in the city had not been realigned). In 1847, when the B&P built a connection to the Providence and Worcester railroad to a better location in the city, the connection to the main line was built a sharper curve—approximately 1.25˚—requiring trains there to slow from 150 to 110 mph today. The curvature is still sharper in Providence itself; until they reach the state line the speed limit is 70.

There are not many legacy rail lines which allow for high speed operation, certainly outside of very flat areas. Railroads want to avoid hills and before high speed operations they were generally built to go around them rather than over or under. Pretty quickly (or in the case of the B&O, very quickly) engineers realized that a 3˚ or 4˚ curve was perfectly fine, especially with stronger rails. No one in 1840 was going 100 mph, it was inconceivably fast. A few 5˚ curves were far easier than moving mountains.

But the Providence Line, because of—as far as I can tell—little more than happenstance, wound up with a high-speed right of way. It will never have 180 mph / 300 km/h service on those curves, and smoothing them out, especially at the Canton Viaduct, is nearly impossible. (The median of I-95 would give a straight-enough corridor for a higher-speed alignment to Providence, which would shave only 2 to 3 minutes off travel times but would allow for more redundancy and capacity.) But for a 190-year-old railroad, it’s not bad. It’s a shame engineers figured out so quickly that 1˚ curves weren’t necessary or we could have much faster rail service much more easily.

Note: here is a tool I created to find the curvature of rights-of-way, and no, I definitely didn’t write this post just to call attention to it. Not entirely, anyway.

Big event logistics and Taylor Swift

Or … the case for a stadium-specific train station in Foxboro instead of a sea of parking.

Football stadiums are big, but where do they “belong”?

Football stadiums are generally unlike other types of stadiums. With a few notable exceptions, baseball parks and hockey/basketball arenas are located in relatively urban areas. While they are sometimes surrounded by parking lots (ahem, Chicago) there is usually (but not always, looking especially at you, LA) relatively good transit access. Baseball stadiums generally seat around 40,000 people and are used for 80 to 90 games per year (plus other events), arenas seat fewer than 20,000 but a basketball-football-event arena may be used more than 150 times per year.

Football stadiums are much larger (generally 60,000 to 90,000) but far less frequently used. Aside from 10 or 11 football games, even a large city may only attract a few acts which can fill a 70,000 seat stadium: the Taylor Swifts and Bruce Springsteens and Beyonces of the world. MetLife Stadium in New York has just 23 large events aside from football this year, meaning it sits idle more than 300 days of the year, and it is likely the most heavily-used stadium in the country. There are only a few stadium-level acts touring at any time (it’s a lot easier to fill a 20,000 seat arena compared with a 80,000 seat stadium) and outdoor events can really only take place between May and October in most places. A large stadium will be a ghost town most of the time, not a great land use if you’re trying to build a vibrant area around it.

A ballpark or arena may see upwards of 4 million visitors per year, spread over 100 dates or more. Football stadiums may barely crack one million, concentrated into a couple of dozen dates. These two factors mean that these large stadiums are often sited differently than smaller arenas in the US. But when nearly 100,000 people descend on one location, it’s not easy to accommodate them. Football stadiums can leverage existing downtown infrastructure (transit and parking) but this can lead to or exacerbate to poor surrounding land use. Or they can be built in another existing, American amenity: the suburbs.

A quick aside: American like our stadiums like we like our highways: big. Of the 11 stadiums with a capacity over 100,000, eight are in the US (all college football, two of the other three are cricket, the third is in North Korea so who knows how big it actually is). NFL stadiums are usually a bit smaller, with more premium seating. Still, they’re big, Americans drive cars a lot, and football fans like to stand outside their cars and eat food and drink beer before the game so with few exceptions, at least some outdoor parking is present.

As Ray Delahanty recently pointed out, it’s tricky to get good land use with that size of an arena if it’s placed near a downtown. I’d go further: in the United States, football stadiums are so big and so car-focused and lightly used they don’t belong downtown at all. There are large stadiums in non-US cities which manage to avoid parking seas, although in general they are located in cities where the majority of people don’t drive (don’t worry, they still drink before the game). Of stadiums larger than Soldier Field, the smallest NFL stadium (62,000 seats), 70 of 153 are in the US, including 29 NFL stadiums and plenty of other college stadiums. (Other countries with at least 3 on this list: UK with 7, Germany and China with 5, Brazil with 4, Japan, Mexico, India and Spain with 3, often with access to multiple metro lines or near a major railroad station.) So midsize metro areas and college towns in the US have larger stadiums than the national stadiums in most countries.

Because of these factors (big, America, cars), football stadiums have developed with a lot of parking. The actual football field of play covers 57600 square feet, or about 1.3 acres (wider soccer fields are about 77,000 square feet). The stadium surrounding the field might take up around half a million square feet, or 10 times more. The parking around a football stadium? It takes 10 million square feet (in some cases, more), about 230 acres, which is worth point out is more than about a square kilometer, or nearly 20 times as much space as the stadium and 200 times as much as the field itself.

Many stadiums are indeed surrounded by this sort of sea of parking. Professional American football stadiums tend to fall into two broad categories: those in the suburbs and those downtown. (Larger college stadiums are often much less parking-dependent: many fans come from the adjacent campus and weekend games utilize campus employee parking which otherwise sits empty). Suburban stadiums are generally parking seas: in nearly all cases they utilize stadium-specific parking. (The two exceptions are in Green Bay, when neighborhood streets, yards and lawns soak up much of the parking demand, and Santa Clara, where nearby office parks can be used for weekend events.)

Urban stadiums are rarely islands in the middle of parking seas. For the most case, they rely on existing parking facilities in the downtown neighborhoods they border. There are two glaring exceptions, both of which somewhat paradoxically date back to the early 1900s:

  • Denver’s Mile High Stadium (or whatever it is called now) is urban-ish. It’s a bit more than a mile from Union Station and the edge of Downtown, too far to take advantage of Downtown parking garages, although there are some closer transit connections. It was originally built on land that existed because it was an early-20th century landfill.
  • The South Philadelphia Sports Complex, which dates to filled river delta area in the 1920s. The original purpose of the land was to build a large arena for the Army-Navy game larger than the ballparks which football fields were typically squeezed into at the time. This led to perhaps the most robust stadium-only transit service in history. Since neither team was local (the game taking place roughly in between Annapolis and West Point), the Pennsylvania Railroad ran dozens of special trains to a temporary station built on a rail yard adjacent to the stadium, handling tens of thousands of cadets, midshipmen and other attendees. The extension of the Broad Street subway line wouldn’t be built until the 1970s.
Grif Teller’s “Mass Transportation” depicting the Army-Navy game trains.

No modern stadium has been built near a city center with a full 10-million-acre parking ocean. Even here the economics don’t work to have massive parking lots only used a few days per year. It makes much more sense to utilize nearby parking garages which are usually empty on Sundays and that’s what generally occurs. There is some space for tailgaters, but most event-goers use parking garages. An added benefit: downtown areas are designed (for better or worse) to accommodate a lot of people arriving by car at the same time, and usually has a decent transit system which can bring in a fair number of event-goers as well. It’s interesting that there are a number of cities with NFL stadiums and no appreciable rail service: Las Vegas, Jacksonville, Charlotte, New Orleans, Detroit, Indianapolis, Nashville and Cincinnati, and only Atlanta really has a heavy rail-served downtown stadium

Moving a lot of people to one location is … hard, actually?

While these stadiums are at the center of urban bus networks, bringing tens of thousands of people to one place on buses is difficult (for instance, loading 20,000+ people onto buses for the Boston Marathon requires closing several blocks of streets to stage buses and to load them in two lanes at a time, a large queueing area, and all this for a single origin-destination pair, so there is no need to direct people anywhere than to “get on any bus”). And even if these smaller cities took advantage of their bus systems, they would be quickly overwhelmed. Nashville’s system only operates 150 buses at peak times, and only carried 11,000 people all day on Sundays before the pandemic. (Indianapolis, Jacksonville and Cincinnati operate on a similar scale, and several other cities’ transit systems aren’t much larger.) Even if buses were used at scale, it would require a huge fleet. At 50 people per bus (meaning selling almost exactly 100% of the seats on a bus, not an easy task), transporting 20,000 people would require 400 buses, plus dispatch staff, crowd control and route planning. This would dwarf the bus fleets of smaller cities, and since the buses would only provide a single round trip, it would require a full shift of bus and driver pay to move a single load of people, not a particularly efficient use of resources.

Picking up a lot of people in one place and moving them to another happens to a task at which mainline commuter trains excel. A 10-car train can carry upwards of 2000 people (more if packed with standees), so even if one third of attendees came by transit (unlikely for a football game, but more likely for, say, a concert for a singer popular with teens and 20-somethings) it would only take 10 trains to transport everyone. Trains could also transport event-goers to park-and-ride lots unused at off-peak times. 10 trains might only require 50 staff, an order of magnitude less than buses to move the same number of people.

Football stadiums are not designed with transit in mind. There are three football stadiums for which commuter rail is the only high capacity transit connection (others—Baltimore, Seattle, Santa Clara, Chicago’s current stadium—have rail lines nearby but more heavily utilize other forms of transit): the Meadowlands in New Jersey, Foxboro outside of Boston and the proposed Arlington Park stadium outside of Chicago. Not surprisingly, these are the three most extensive commuter rail networks, and in each case, the rail connection is made far outside the city. Each city provides an interesting example of how commuter rail service does, or does not, provide transit access to large events.

Chicago (Arlington Park)

Chicago doesn’t have a football stadium served by commuter rail, yet, but it may not far in the future. The Bears are planning to move from the smallest-in-the-league, 100-year-old Soldier Field on the periphery of Downtown to a larger, more modern suburban stadium on the site of an old racetrack. It’s hard to fault them for this: a new stadium downtown or anywhere near transit would require a large site that would only be used a few times per year. (I guess adjacent to the United Center or Comiskey would work?) Arlington Park is about 20 million square feet (nearly a square mile, three times the size of Suffolk Downs in East Boston) and adjacent to a three-track commuter railroad, which can support frequent service and a 30 minute ride into the city (it also runs on a diagonal through the Northwest side of Chicago, with a number of stations allowing bus and L connections).

Unlike some agencies, Metra is actually pretty good at running extra service to meet extra demand, and would likely be able to stage as many trains as were necessary to move people from this new arena to the city, and also to satellite commuter parking lots along the line. The third track of the railroad would allow the agency to stage as many trains as necessary to handle crowds while maintaining regular service. The station has two adjacent storage tracks, and a new development could allow for an expanded station to manage higher loads. The Bears’ plans don’t call for a sea of parking, but rather a mixed-use development next to a train station. Would I call it a perfect location? I might not go that far, but it’s a decent place for a 75,000-seat football arena.

New York (New Jersey Meadowlands)

Both the Jets and Giants play in the Meadowlands, build on reclaimed land in the swamps in New Jersey. The shared use of of the stadium means that it gets somewhat more frequent use than it otherwise would (a low bar; it still lies dormant more than 300 days each year), and with many non-drivers in the area a rail spur was eventually built to take people to and from the stadium. (It only cost $185 million—equivalent to $265 million today—for 2.3 miles. Really. It may serve 500,000 people per year, or about 1500 per day on average. And it may not even be the biggest boondoggle in the Meadowlands.) Other than events, there is no use of the line, which only serves the sports arena and the American Dream shopping mall, which opened after a 25-year, on-and-off construction period and may be all but stillborn, hemorrhaging money now that it has finally opened its doors (i.e., boondoggle). For football games, it works fine, with between 6000 and 10,000 people arriving and departing by train. For larger events, like line has been overwhelmed since the stated capacity of the line is just 8000 to 10,000 per hour.

This speaks to a bottleneck somewhere along the line:

  • Perhaps it is an undersized station, with just three tracks (the rail station at Belmont Park on Long Island was originally built with eight tracks, although only two are now in regular operation). 8000 to 10,000 people per hour means that the rail line only supports a full train every 12 to 15 minutes, which hardly seems like the capacity of the line. With three tracks, the Meadowlands station should be able to turn a train in 15 to 20 minutes on each track (and that’s generous, since trains are only loading or unloading at any given time passenger traffic flows in one direction) meaning that the station should support 9 to 12 trains per hour.
  • Maybe line capacity? The upper bound of the station may stretch the capacity of a two-track railroad with diesel trains and an intermediate stop and existing service; the 18-track terminal at Hoboken would be able to swallow the traffic at the other end of the line. The Pascack Valley, Bergen and Main Lines, which share a trunk route into Hoboken, only amount to three trains per hour at off-peak times (when nearly all concerts and events end, either on a weekend or late in the evening). These lines support 12 trains per hour through Secaucus and into Hoboken at peak hour, meaning that 9 stadium trains plus the normal service would be reasonable. That should allow 18,000 people per hour to be moved.
  • My guess is that it’s simply the number of trains on the line for high-use events, and inexperience of the agency. With a cycle time to Hoboken and back of more than an hour, NJT would have needed more than a dozen trains on the line to fill the theoretical capacity of the line and station, so rather than having trains stacked up on the line ready to pull into the station, they were relying on six trains to make the round trip and come back for more. This is certainly better for crew utilization, but not so great for the passenger experience.

The 2014 Superbowl, where fans were highly encouraged to take transit, was a stress test the railroad seems to have failed somewhat spectacularly. It took three hours to clear 35,000 people from the stadium; 12,000 per hour is actually higher than the stated capacity (likely as people pushed onto trains) although some very helpful Internet people suggested just running buses without pointing out that they would have needed about 700 of them. If I had to guess, the issue was a lack of trains and crews:

Boston (Foxboro[ugh])

Which brings us to Foxboro, the third stadium near a commuter rail line. Sort of. There hasn’t been regular passenger service on the Framingham Secondary since 1933. 40 years later, the stadium itself was built, on a shoestring $7 million budget on donated land. At the center of this land deal: parking. The league stipulated that teams play in 60,000-seat stadiums. The itinerant Patriots had used a number of smaller venues: Fenway Park, and three small college stadiums (Harvard, BU and BC) and unlike the Bears, which moved from Wrigley to a “temporary” home at Soldier Field (they’re now looking to move half a century later), there was no large-enough structure in the area.

The owner of a local racetrack offered the land for the stadium but kept the adjacent parking lots which would now generate cash for both horse races and football games. The site happened to be adjacent to a rail line, and from early on some event service was provided. Service, however, is minimal, since the rail line isn’t designed for much more than a few freight trains. In general there is one train from Boston and one from Providence (the Boston train usually sells out) which meet at the platform. There’s no room for anything more. Aside from the poor local infrastructure, the railroad could support direct service from Boston, Providence and Worcester, theoretically linking the stadium to the three largest cities in New England, provided there was room to store more than two trains.

In the past 50 years, Foxboro’s sea of parking has grown, as the complex owner Bob Kraft has since developed a large shopping mall adjacent to the stadium (more of a lifestyle center than the atrocity that is the American Dream in Jersey). This is not a good setup for traffic as Foxboro is accessed by Route 1, a four-lane highway with traffic signals, and traffic is notoriously bad after games (one review calls it a “great stadium with terrible traffic,” a microcosm of Boston, depending on your definition of “great”). Lots of advice to beat the traffic is to take the train, although it means no tailgating and capacity is limited.

Most everyone else has to drive. There are two ways to distribute a lot of vehicles parked in one place. One is to surround the parking lots with highways and ramps (either in the suburbs or downtown). Another is to disperse parking near the stadium, allowing it to filter through nearby neighborhoods (Green Bay does this, but no one in Green Bay complains about Lambeau Field, which is probably against several state laws). Foxboro is located in the corner of a far-flung suburb a quarter the size of the stadium’s capacity. Decisions are made by an open town meeting. The stadium is located on a local four-lane roadway with traffic lights before it spills onto nearby highways. Traffic jams are legendary.

In 2019 the MBTA started, then aborted with the pandemic, and now restarted, a yearlong pilot to bring regular service to Foxboro, partially subsidized by Patriots ownership. Parking is provided for free, which may help apparent ridership, but there’s really little other reason for most riders to go to Foxboro instead of another nearby station, especially since rush hour service from nearby Mansfield is a faster trip by 20 minutes. (Before the pandemic, other lots would be full, but even with ridership bouncing back, parking scarcity is not as much of an issue.) With nothing but parking lots for a mile in any direction, there is about as much need for transit service to the site as there is to a mall Jersey. High ridership, for now is little more than an American Dream.

A station for Foxboro (and Tay Tay and … the World Cup?)

Which is not to say there shouldn’t be a station there. It should, if the 12 million (half square mile) of land were ever developed as something other than parking lots. It may be the largest developable plot of fully-impacted land in the region. And it happens to be next to a railroad. So while the current pilot may not be successful, if the surrounding area were home to 5,000 housing units it would make far more: Windsor Gardens, but on steroids, an anchor a the end of the line. I’m sure the citizens of Foxboro, who enjoy the largesse of the stadium’s tax revenue while keeping the traffic on Route 1 on the periphery of town, would throw a fit, but in Boston right now, nearly any housing is good housing. Transit-oriented? Even better. (In the very long run, a shuttle train to a connecting service on the higher-speed Providence Line might make more sense.)

In the short run, however, the line is wholly inadequate for handling crowds: it consists of one long platform which can handle, at most, two trains, and the slow, single-track lines in either direction make it nearly impossible to store or stage additional equipment near the stadium. So once a train is sold out, it’s sold out. For Patriots games, there’s not too much demand past what is provided. But when a different demographic comes to town, the situation can get dicier.

Enter Taylor Swift. The only ticket hotter than a T Swift ticket to Foxboro was a ticket on a train to get there. Rather than the SUV-driving, tailgating, suburban type, Swifties seemed happy to snag a seat on Commuter Rail from Boston, such that the first batch of tickets sold out almost instantaneously, and when more were added, they went in 90 seconds. (The Swifties who did get onboard seemed to enjoy themselves!)

The lack of any terminal facilities in Foxboro means that there is no way to leverage the existing rail line to bring crowds to the site and reduce the need for parking, parking which could be repurposed for something other than a parking lot only used a few times per year. There is plenty of room for an event rail terminal not significantly different (although at a smaller scale, sketch here) from what the Pennsy ran for the Army-Navy game, in essence, a few tracks facing in each direction allowing trains to park and unload passengers before the game and then swallowing them up afterwards. It need not be fancy, just ramps to platforms to allow accessible boarding for trains waiting for the crowds.

This would allow multiple trains for football games, where there is more demand than current supply and plenty of capacity at nearby park-and-rides at game times. An express train could run from Boston with a local train picking up passengers parking at nearby stations and using the train to avoid the last few miles of gridlock. For an event like a Taylor Swift concert, as many trains as needed to transport the requisite masses. Full trains make money. If the Cape Flyer makes a profit on an $40, 160-mile, 5 hour roundtrip with a couple hundred passengers, 1800 people on a $20, 60 mile roundtrip should be a cash cow. The agency has the resources at off-peak times, and events are scheduled far enough in advance that labor could be arranged well ahead of time. But the real value is in repurposing the land around the stadium from parking to something more beneficial to the region.

It’s hard right now to make an argument that the current Foxboro Stadium land use needs regular transit service. In a region with a housing shortage and relatively few large sites adjacent to rail lines, the half square mile of parking could be put to far better use if it weren’t needed and there was enough transit service to allow people to get to the stadium without driving (even if it just meant parking at an existing Commuter Rail lot elsewhere and taking a train). Should the public pay for this? Certainly not. But if improved rail service were funded by Bob Kraft, it would be a good investment which could leverage the value of the acreage around the stadium to be something other than parking cars for a few days each year.

In the shorter term, Foxboro will host at least 6 games of the 2026 World Cup. These fans will be much closer in demographic to a T Swift concert (international, interested in soccer, less interesting in tailgating) and many will be staying in hotels in Boston (and probably Providence, too). If the T can’t figure out how to manage moving more than 3000 people to and from the stadium on trains, they’ll have to have a fleet of buses, and all of the logistics that go with that. So if there is a good time to build a stadium terminal which can handle larger crowds that time is now.

Queuing theory, inefficient Search Algorithms (or … where’s my bag at the Boston Marathon?)

I’ve run the Boston Marathon five times now, and during three of those, I’ve waited for my bag in a cold rain at the end of the race. While this is certainly preferable to the alternative, the marathon’s bag pick-up illustrates how systems can experience bottlenecks even if the overall system has plenty of capacity.

Boston is a unique race in many ways, but because it requires qualification for most runners, it is perhaps the most “densely-populated” marathon in the world: rather than spreading finishers across a four hour window (2 to 6+ hours), most are concentrated in the qualifying window (under 5 hours, depending on age, with most runners under 4). It certainly isn’t the largest race: New York, London, Paris, Berlin and Chicago all clock in around 50,000 runners, while Boston has settled in at a maximum size of 30,000.

The reason that Boston is smaller is that unlike those other races, it starts in a small town, takes over the high school for the athletes village, and the first few miles are on a two-lane wide road with no shoulders, meaning that even spread across four distinct waves, there are only so many people who can be bused to the start of the race, lined up, and started. (Chicago, by contrast, starts and ends in the Loop, Berlin, London and Paris are served by massive transit systems and New York uses an armada of buses to move people a couple of miles from the ferry to the start, which happens to be on to a major highway). On race morning, the parking lot behind the Hopkinton CVS is a sea of port-o-johns; New York uses the 160-acre Fort Wadsworth, Chicago starts in the middle of Grant Park.

(Aside: as I stood in line for the line for mobile urinals—a Nobel-worthy invention in the field of race waste management—people next to me worried we’d miss the start. “Nonsense,” I said, doing some quick math. “There are 80 urinals. There are about 250 people ahead of us in line. If each person takes 1 minute, we’ll be done peeing in 4 minutes.” We were. Logistically, each urinal holds about 400 liters and men can pee 10 to 20 ml/sec per the Internet, so these urinals will not fill up during the 90 minute pre-race pee period. Let’s move on.)

The roads in Boston eventually widen, although most of the course is less than four lanes wide. When you take this relatively narrow course (parts of London are narrow as well), and add, unlike the other races, the seeding of qualified runners, it means that the field never spreads out. Marathon finish times mostly resemble a bell curve (although with some eccentricities, discussed momentarily). The “average” marathon has a median time of about 4:30 with a standard deviation of about an hour. Boston has a median of about 3:45, with a standard deviation of only about 40 minutes. (Standard deviation data can be found here; European races tend to be a bit faster than American races on the whole per the study linked below.)

Why is it not an exact bell curve? Because many runners attempt to—and generally succeed in running—specific times. [2:59:56 marathoner this year raises hand.] Here is a very interesting business school paper on reference-dependent preferences which included the results from several thousand marathons and shows the distribution of marathon finish times.

Distribution of Marathon Finishing Times (n 9,789,093) 

The n in this study is 9,789,043, so 100,000 finishers is just about 1% of the race, and other than a peak right around 4 hours, most of the race is under 0.8% per minute. Boston, on the other hand, has a solid hour with more than 0.8% of the race finishing, with a peak minute of 1.4% or 372 runners (in 2023) and several other minutes around 1.2%, or about 320 runners per minute. And that peak reference-dependent preference is a full hour earlier.

In other words, in a typical marathon, 40% of the runners finish in the peak hour (between about 3:35 and 4:35). In Boston, 60% of runners finish in the peak hour (between 2:55 and 3:55). 40% of runners finish across just 38 minutes, a rate more than 50% higher than typical.

Add to this: Boston’s runners are very well-seeded, so the heavy waves tend to start and finish together. In nearly every large race, runners are sorted into waves to start, with each wave starting every 25 to 35 minutes (rather than having one huge field stage and take 30+ minutes to clear the start). In larger races, the wave start means that although there is a peak between 3:55 and 4:00, that peak finishers are spread across multiple start waves. Most runners near the peak in those races do not have a qualifying race time, and are seeded based on interpolated times from other races.

Meanwhile, in Boston, the first three waves of runners almost all have qualifying times based on a recent marathon and are seeded quite well. Boston has less of a reference-dependent preference signature other than at the 3:00 mark, which happens to be the qualifying time for men under 35 and a significant goal for many runners. In fact, the largest single race for people qualifying for the Boston Marathon is usually the previous year’s Boston Marathon (the only exceptions are when the weather is uncooperatively warm). So in other races, at the peak times, runners are spread across multiple waves (not finishing all together), while in Boston most runners coming in at peak times started together (and in some cases ran the whole race within earshot).

Note: I could go and scrape start and finish data with gun times to go into this further, but for now, just trust me on “Boston has a lot of runners finishing together.”

Data from here. A few notes: the BQ standard was decreased by 5 minutes for the 2013 and 2020 races. 2004 and 2012 were run with temperatures in the 80s; 2012 allowed deferrals. 2013 was cut short because of the bombings, but at that point nearly all potential qualifiers had finished; 2014’s field was larger and consisted of many people who hadn’t finished in 2013; most were not qualfiers. 2016 and 2021 were relatively warm years. With 13,700 BQs run, 2023 Boston is the largest number of Boston Qualifying times ever run in a single race. This will likely mean that, after two years where all qualified runners gained entry to the race, there will be a cutoff in 2024.

This all means that at peak finishing times, there are not only 1000 people finishing per minute, but for much of the race, those people all started together. And what does this mean for bag pick-up? Here’s how bag drop works:

  • Before the 2013 attack, Boston had bag drop at the start: you gave a volunteer your bag and it showed up in Boston on a bus a few hours later. (See DC Rainmaker’s blog post, back before he started reviewing every device.)
  • After 2013, a bag drop policy was instituted at the start: you left your bag there and took a disposable bag to the start (and for cold years, wore extra clothing, transferring throw-away items from the Goodwills in Boston to Hopkinton).
  • Setting up a bag drop system for 20,000 or more bags requires erecting the infrastructure in Back Bay the day of the race; at first, this was tents and rows of bins with bags, the system has now morphed into one where you drop your bag at a school bus where it is stored through a window specified by your number range, allowing the storage units to be rolled away after the race (this, on its own, is a very good idea, here’s an image which shows how the easy part—the drop-off—works).

However, the system is still quite space-limited. Most every other big marathon ends in a park, or open area. Boston ends on a main street in the middle of a city. So there is not much room for queuing or storage for the bag drop. Which means that each bus stores approximately 1000 runners’ bags. Which is fine when they are dropped off: runners arrive over the course of about an hour per wave, with some early birds and some late arrivals, meaning about 15 drop-offs per minute, and drop-offs do not have to be sorted to the right person, only put into the right “bin” (a window of a school bus and on the inside, I assume, a numbered seat).

The buses are lined up by wave (red, white, blue, yellow) and then bags are ordered within each wave (1-1000, 1001-2000, etc). It is easy for race volunteers to look at a runner’s bib color and send them in the right direction to drop off their bag. They do, and go off to run their race.

On the pickup end, however, metrics are reversed. 1000 runners may show up over three minutes, and I’d guess as many as 600 of them may all need to get their gear from the same bus. Simply throwing random bags to runners would require, at times, more than three bags per second to be thrown at participants. But unlike drop-off, pickup requires sorting through as many as 25 bags (assuming a bus has 30 seats and bags are sorted into these seats). Without perfect ordering, volunteers search through the pile of bags until they retrieve the correct one. This may take 10 to 20 seconds or more, and even with five or ten volunteers on the bus (there really isn’t space for more), it means only 15 to 60 participants receive their bag each minute. If we assume the geometric mean here of 30 runners served per minute, it would take 30 minutes to serve all the bags in a bus, resulting in long queues.

As this occurs, a wave of long queues forms. Once the high rate of finishers starts around 2:50 from the start, the buses have long lines which form a slow-moving wave from bus to bus. After waiting for my bag in the 4000s for a long period of time in the cold rain (as I have in 2015 and 2018) I shuffled past the bus ahead of me with the 3000s. Aside from a few stragglers, it had no queue, the volunteers there had retrieved all of the bags and were catching their breath. Meanwhile, the queue behind me at the 4000s bus was ebbing, while the queue at the 5000s bus behind us had grown. But elsewhere, three-quarters of the buses, for the white, blue and yellow waves, wouldn’t see their first runners for, in some cases, an hour or more.

In introductory computer science courses, students are often taught about efficient search algorithms. Let me stop here and state that I am completely unqualified to write in depth about the efficiency of search algorithms. But mostly, it is very inefficient to search through an entire unordered list each time you want to find an item. It’s better to either sort the list (and then search through it) or sort the search term in a way that only searches part of the list. (That said, this is, let’s just say, a simplification, people write dissertations about this.)

Essentially, searching an unordered list is what the pile of bags search is. One solution would be to build a better sorting apparatus: I have participated in the American Birkebeiner ski race every year since 2006, and even produce the most popular (read: only) podcast about the race. Drop bags there are sorted and lined up, by number, in a parking lot, and distributed to finishers. This would work in Boston, if only there were several acres of parking lots in the Back Bay which could be used to stage the bags. Fortunately, urban renewal mostly steered clear of Boylston Street (the Pru was built mostly on old rail yards) and we lack the luxury of this open space. The school bus solution allows the apparatus to be set up on the streets, while providing cover from the weather for the bags (and volunteers), but does not lend itself to sorting beyond these bins.

If finishers were better distributed amongst the two dozen (or so) buses as they crossed the line, the sorting problem would be less of an issue. If 240 of 300 people crossing the finish line each minute had dropped a bag and they were evenly distributed amongst the buses, it would mean 10 people per bus per minute, and if five volunteers were on each bus, it would allow 30 seconds per bag for each user without long queues forming. The issue is that with this inefficient search algorithm—which is necessitated by the location of the bag pickup—has concentrated finishers. Hundreds of finishers wind up at a single bus at any time, and there are only so many volunteers who fit on this bus. When these “servers” can’t keep up with the demand of the “customers” (to use queuing theory terminology), the queue grows exponentially until, at some point, the wave of runners ebbs, and the speed at which customers are served exceeds the additions to the queue, and the lines dissipate. Of course, by this time, a similar wave has moved to the next bus down the line.

The author’s 2023 drop bag. Note that this bag (or at least, the 2022 version) can hold a 30-rack of beer (not pictured). No word on whether anyone has ever dropped off a 30-rack.

There is, I believe, a solution to this problem: sort the customers before they get to the bags. The main issue with this setup comes from a concentrated wave of people overwhelming a single service point. If the people were dispersed to more servers, it would allow more efficient use of the volunteers, rather than having one bus overrun while others lie idle. There is a simple way to do this: sort first by the last digit of the bib, and then by bib color and number. This would decrease the concentration of the customers by an order of magnitude, distributing them across the buses, rather than having them queue up in one place where there aren’t enough volunteers to handle them.

Here’s how such a system could work. When the BAA gives out drop bags, runners affix a sticker with their number and wave color. For instance, it might say:

4 8 7 6 or 1 8 7 6 5

This allows a rough sort by color and then number, but color is simply a function of the number, so it does not spread out the customers. Here’s a proposed redesign:

4 8 7 6 or 1 8 7 6 5

What I’ve shown here is that the numbers could have the final number highlighted to help inform people of the new sorting method, allowing the runners to be sorted first by the final number of their bib, and then ordered by their number. This would reduce the concentration by a factor of 10.

Directions about the changes could be given to runners with their drop bag sticker, as well as at the bag drop-off in the morning. Instead of signs pointing to different colors, they would instead point to numbers: 0 to 3 to the left, 4 to 6 to the right, 7 to 9 straight ahead. The start would be less tricky: before the race, people are generally more mentally aware than after running 26.2 miles. Once overcoming this small hurdle, runners would proceed to their number, then to the bus assigned to their color (each bus would likely have two waves assigned) and then the correct range. It would introduce an extra sorting step at the start, but would pay dividends later on.

The finish would introduce more complexity: runners and volunteers would have to direct people based on the last number of their race bib. This would be mitigated in a couple of ways. First, racers would have already experienced the system before the race. Second, volunteers already have to sort barely-cogent runners stumbling their way along Boylston Street by color, so they would instead sort “right/straight/left” by bib number. Once on the right street, runners would be able to find their correct bus by last digit and then color and join a much shorter and congested queue. Rather than 15 to 30 minute queues for bags, most runners would be served in just a few moments.

It might also allow the race organization to cut down on number of volunteers required for the system. Rather than moving volunteers between buses as demand changes, each bus would have even demand during the entire bib pick-up procedure. This would reduce “deadhead” time when volunteers are required to move between buses as they are needed elsewhere, by allowing them to maintain a single duty station during the entirety of the bag pickup process. There would still be 300 or more finishers per minute, but they would be spread across 10 pickup locations at any given time, not concentrated at a single site.

Since this is sometimes a transportation-related site, there is a lesson here in the transportation planning realm: A system which seems efficient may have an unforeseen bottleneck which creates a single point of failure, meaning that a small portion of the system is oversubscribed while the rest is underutilized. A wide highway might encounter a lane drop or even a situation where traffic has to sort into different lanes, resulting in a long backup. A rail line may have plenty of capacity along most of the line but a busy station with long dwell times or a single switch may curtail capacity along the rest of the line. For the Boston Marathon bag pick-up, the well-intentioned decision to simplify the drop bag system results in a bottleneck of hundreds of cold runners huddling under thermal sheets, all too often in cold rain. Simply by changing some procedures, this may have a fix which would benefit everyone involved.