How the North South Rail Link could work

North South Rail Link schematic showing current train volumes for Commuter Rail
lines, potential future RER-style connections and new and existing stations.

Discussion about the North South Rail Link has bubbled up again, with Mike Dukakis and Bill Weld writing in the Globe about how it should be a priority, Commonwealth magazine calling them out on where the money would come from, and Dukakis replying that if you wanted to find the money, you certainly could. A thread started on Universal Hub with a lot of people wondering how the rail link would function. Here are my thoughts/explanations.

Efficiency. The crux of the issue is that MassDOT wants/needs more space at South Station (and eventually North Station) and is limited by the number of tracks. Turning trains around is time-consuming: you have to unboard (deboard?) the train, board the train (even at rush hour, 50-100 or more reverse commuters may be waiting), have the crew change ends, and then thread out the same slow trackage you came in. Even with the best of practices, a terminal station track can only accommodate a train every 15 minutes or so. But if trains run through, boarding and alighting is faster and easier, there’s no need for the crew to change ends, and with more destinations,  fewer passengers get off at each stop. You could route 20 trains per hour per track, meaning that four tracks in the rail link could do the work of 20 at South Station (currently there are 13; the expansion would add about a half dozen more).

Electrification. You need to electrify the whole system (and maybe Amtrak to Portland). Maybe you could get away with dual mode engines, but that’s lipstick on a pig. Electrification of the Commuter Rail network would cost somewhere in the neighborhood of $1 to $2 billion dollars. Not cheap. But huge operational efficiencies: electric trains are cheaper to run, cheaper to maintain, and have faster acceleration meaning that trip times (and staff costs) are shorter, while ridership is higher (faster trains = higher ridership).

North/South imbalance and the Grand Junction. The idea behind the North South Rail Link is that trains coming in to South Station run through the tunnel and out one of the North Side lines. This is the Philadelphia model. This works well in theory (some passengers would get a one-seat ride; others would have to change), but in practice more trains run in to South Station than North Station (although this was not always the case; in 1972 there were twice as many passengers at North Station). Several pair off relatively well:

Old Colony Lines-Eastern Route

But falls apart when you realize that all the North Side routes are taken and you haven’t accounted for the Worcester or Fairmount Lines. You could route them through to other terminals, say, to Anderson Woburn, but this seems wasteful; you don’t need a train every 8 minutes inbound from Woburn. This is where the Grand Junction comes in. If it were grade-separated in Cambridge (or maybe even if not; there are grade crossings in downtown Chicago with 20 trains per hour at peak times), Worcester Trains could split off at West Station (hopefully) and make a loop (much like lines in Melbourne, where a similar imbalance existed), serving Yawkey, Back Bay, Downtown and Kendall. As for the Fairmount Line …

Potential for RER(/S-bahn/Crosslink)-style service. Having the rail link in place with the Grand Junction connection would not only allow you to route trains through the city, but it would also allow you to implement RER-type service filling much of the urban ring and providing more frequent service than Commuter Rail (although Commuter Rail could run more frequently as well). If all the paired lines shared one set of tunnels, the Worcester Line could share the other with the following RER-type services:

Allston to Assembly via Cambridge (Kendall) and Sullivan
Readville to Allston via Downtown and Cambridge (Kendall)
Allston to Chelsea via Downtown and Sullivan

These would operate frequently all day, every 10 to 15 minutes, allowing transfers between subway and Commuter Rail. This leverages the capacity of the rail link to create a complementary urban rail network to provide new connections and take some pressure off the existing hub-and-spoke network.

Get rid of North Station. Most ideas about the Rail Link include three downtown stations. But you only need two. Where North Station is today is convenient to very little, and the half mile to its north is taken up by highway ramps and water. A better idea would be a station between Aquarium and Haymarket. It still allows for transfers to all subway lines, and there is very little that is less than a 10 minute walk from North Station but more than a 10 minute walk from Haymarket. It would save money, too. (Obviously, the existing Green/Orange line station would remain.)

Open new land to development. Much of the land near North and South Stations is taken up by trackage, and the Rail Link, obviating the need for these stations (a couple of tracks to use in emergencies and for trains like the Lake Shore Limited might make sense, at South Station especially, although these trains could operate to West Station and provide connections there instead), and this would be very valuable land. In addition, it would render Boston Engine Terminal obsolete as maintenance would be for electric vehicles, and if maintenance facilities were rebuilt on less valuable land (say, in Billerica or next to the Anderson/Woburn station). Based on what Northpoint just sold for, it would be worth maybe half a billion dollars in development rights. A lot of this money could be captured to help pay for the rail link itself.

Will the North South Rail Link happen any time soon? Probably not. But hopefully this will help people understand its potential (which is huge!) and what we’re talking about when we talk about the NSRL.

What if the Allston Viaduct was rebuilt … without a huge highway viaduct?

I’ve gone to my fair share of meetings and written quite a bit about the Allston viaduct project.

The long and short of it: $250 million for a replacement viaduct basically replicating the old one, and maybe some transit, walking and biking improvements if they can “find” the money. Everyone agrees the project has to happen: the viaduct is falling down. There are preliminary plans, and arguments over how big and wide of a viaduct to build.

But what if you didn’t build a big, wide viaduct at all? If you think outside the box (as this page has before), there’s the potential to save money. Considering how much cheaper it is to build other roads at grade, potentially lot of money. $50 million. Maybe more. The resulting highway would be safer, have better grades and sight lines, and integrate better in to potential development in Allston. It just requires a slightly change of the state of mind.

I won’t blame anyone for not realizing this earlier. I’ve been writing about this for years and it took a prompt to see if everything would fit at grade to figure it out. (The answer is you’d be about 30 feet short of lateral space to put everything at grade, and you still need to cross the Turnpike and Grand Junction.) But once you change you frame of reference, elevating the Grand Junction over the Turnpike, instead of the other way round, makes a whole lot of sense.

$250 million is a lot to spend for a mile of roadway; much of that cost is in building a high-and-wide viaduct, supports and steel and drainage, and said viaduct then costs more to maintain. This project has a lot of moving parts (bike/ped paths, Soldiers Field Road, Mass Pike, four railroad tracks going to two separate destinations) in a narrow corridor, including one (the Grand Junction branch) which has to cross another (the highway). But what if you could do it all without a hulking, expensive highway viaduct? An at-grade highway would save a lot of money. It would cost less to maintain. And it would remove the Great Wall of Allston between the river and the neighborhood.

With the state budget deficit and without increased gas taxes for infrastructure spending, we need to fully analyze projects so they are as fiscally responsible as possible. In this case, the project is necessary—the viaduct is the same age as the crumbling nearby Commonwealth Avenue bridge—but replacing a viaduct with another viaduct is far more costly than moving as much of the project as possible to grade. There is a way to do this—to build much less elevated structure—which would likely save tens of millions of dollars. We need to seriously consider it, although so far any project which does not include a large, wide road viaduct has been dismissed out of hand. That must change.

I think it comes down to priorities. With so many moving parts, there needs to be some back and forth. Certain things are immutable: you can’t get rid of the Turnpike, or the railroad. Others—what goes where, construction impacts, and the like—can be changed. So here is a rundown of priorities, roughly ranked:

  • Retain Turnpike capacity at completion.
  • Retain Worcester Commuter Rail at completion.
  • Retain two-track right-of-way for Grand Junction at completion.
  • Retain Paul Dudley White path along river.
  • Provide connectivity for a future West Station
  • Minimize cost.
  • Maximize economic development opportunities by minimizing above-grade land use for transportation infrastructure in the Beacon Park Yards area.
  • Minimize disruption to rail and road traffic during construction.
  • Improve quality of life for surrounding neighborhoods. 
  • Add width to highway to improve emergency lanes and sight lines.
  • Build a “People’s Pike” connecting the river to Allston and Boston University
  • Improve parkland along the Charles River.

The first four items are the immutable ones. A project which fails to address them is dead on arrival; Turnpike is not going to become an Arborway-like boulevard with crosswalks and bike lanes (at least not in the next 50 years). But beyond that, it gets more interesting. The most complicated piece of the puzzle is getting the Grand Junction rail line from the south side of the Turnpike to the north side. Since 1962, it has gone underneath the roadway, and perhaps because “we’ve always done it that way,” all the plans for the future have the same scenario. Yet this requires a large, wide viaduct, and those don’t come cheap. And even setting cost aside, it turns out that it might not even be the best way to build the project anyway.

If you take a few steps back, the highway viaduct just doesn’t make sense. The Grand Junction is two railroad tracks wide, or 30 feet. The Turnpike is, at a minimum, 110 feet wide. Why not put the turnpike at ground level, and build a viaduct that is one quarter the width ? Does it make sense to put the wider, higher, larger structure above the lower, narrower one? No. Elevating the Grand Junction would be far less expensive.

What’s more, on the eastern end of the project area, the Turnpike passes underneath Commonwealth Avenue, while the Grand Junction passes over Soldiers Field Road. 1000 feet out from the narrowest part of the corridor, where one has to pass over the other, the Grand Junction line is 16 feet higher than the Turnpike. Yet the railroad slopes down and the Turnpike ramps up, as they zigzag in vertical space to attain the necessary grade separation. From a terrain standpoint, putting the Turnpike at ground level just makes sense.

In the current setup, coming from Cambridge, the Grand Junction ascends to cross Soldier’s Field Road, and then descends sharply at a 1.3% grade to move under the viaduct. The roadway, on the other hand, ascends at a 3.5% grade to the viaduct, and then nearly as sharply at the other end to reach the toll plaza. This results in limited sight lines on the Turnpike. In the proposed Grand Junction viaduct, the ruling grade of both the road and the rail line is reduced; the rail line requires a 1.1% grade towards West Station (although this could be mitigated by slightly raising the elevation of the Worcester Line tracks), still better than the current 1.3%. And the highway has no grade steeper than 0.5% west of Comm Ave, where before it was seven times as steep, improving sight lines and safety.

The charts below show the gradients for the current and proposed scenarios. The map below corresponds which each of the letters shown on the charts (data from MassGIS LiDAR data). Note how the Turnpike starts and ends at a lower elevation than the railroad. It makes no sense to have it resemble a rollercoaster.

What we have right now is a half-mile-long, eight-lane-wide viaduct to cross a double-track railroad right of way. It’s as if a highway were tunneled under a small stream instead of going over it on a small bridge. For whatever reason, a highway viaduct may have made sense in 1962. It doesn’t today.

MassDOT “considered” elevating the railroad, but they dismissed it as infeasible. Why? Because they assumed that all four tracks of the railroad would have to be elevated. I don’t think it’s nefarious; I think everyone’s mindset is that the highway has to go over the railroad, because that’s how it’s always been. But the Worcester tracks stay on the same side of the highway as the whole way: they can stay at ground level; there’s no need for grade separation. The Grand Junction is much easier to elevate, and requires a much narrower structure, too. Here are three slides (from here) dismissing the overhead rail line as impossible, and my annotation on each as to why it is not the case. (Click here for full size.)

One issue is that MassDOT “requires” 135 feet of highway width for full-width shoulders. While this is “Interstate standard,” waivers can be granted for constrained areas, and much of the Turnpike (including the existing viaduct) doesn’t have any such lanes. If the highway is kept at grade, it will have much gentler grades and better sight lines. This added safety will mitigate the narrow width—and such a compromise would allow for better use of the corridor as a whole.

So you should kee the Grand Junction line high, and the highway low. Westbound drivers would cross under Commonwealth Avenue and then stay level. From their right, the Grand Junction line would ascend slightly—about 5 feet at a 1˚ grade—and pass on to pedestals over the center of the highway. It would continue down the center until it curved off to the left towards West Station and descended to grade. This is not a novel concept: the JFK AirTrain in New York operates in a similar manner in median of the Van Wyck Expressway. And since initial foundation work could be completed under the existing overpass early in the project, the bottoms of the pedestals and median could be pre-built with minimal impacts to traffic; less of an impact than shown here. One note: the AirTrain uses lighter vehicles than the Grand Junction, so it may require more closely-spaced supports and a somewhat thicker deck akin to what is used for other “modern” T bridges like the Eastern Route crossing of the Mystic River.  (The photo on the right is of construction of the Van Wyck AirTrain, from this site.)

Which of the following is more inviting?

Since the AirTrain is elevated above cross streets as well, it’s quite a bit higher than a viaduct would be in Allston, what a cross-section would look like from the Paul Dudley White Bike Path is similar to what it looks like when it crosses a cross street. That’s a bit less obtrusive than this. Or see below:

The photos above are actually taken from approximately the same distance away. Note how much more of the sky you can see above the Van Wyck. Wouldn’t you rather have something like the image on the right?

Not only is it one third the width, but it appears (and, in fact, is) lower for two reasons. In the nearby Prudential Tunnel, roads require about 14’3″ feet of clearance, trains 16’9″, so a road viaduct over a rail line is higher than the other way around. Second, trains don’t require guard rails. Put together, these add up to the top of the structure being six or seven feet lower for a rail structure. Much like how the Somerville Community Path is being built as part of the Green Line Extension, the “People’s Pike” path, it could cantilevered off the side of the Grand Junction viaduct (with additional support extending to the higher ground in—and connections to—Allston, if necessary). For an observer standing on the Paul Dudley White bike path, a rail viaduct in the median of the highway would be visible up to 6˚ in the sky, and 15˚ when a train passed over. By matching the initial grades, the highway can be lower than the Grand Junction since they don’t have to swap positions. The nearer and higher highway alternative would be visible in 20˚ of the sky, and 25˚—nearly a third of the way to vertical—when traffic is taken in to account. The smaller rail viaduct would cast many fewer shadows across the bike path and river as well.

Here is a cross section of my plans and the viaduct plan. Colors denote uses, and are scaled to the height of the users/vehicles. Scale in feet:

By elevating the Grand Junction, there is enough room for the rest of the uses:

  • 14 feet for the Paul Dudley White path (an increase from 8 to 10 feet now, narrower in places)
  • 24 feet for each side of Soldier’s Field Road, with a two foot median and two feet separating the bike path. This is the current width, and the road would need little modification overall.
  • A four-foot barrier between Soldier’s Field Road and the Turnpike.
  • 54 feet of travel space for each side of the Turnpike, enough for four twelve-foot lanes, a two foot left shoulder and a four foot right shoulder, with a six foot median where the supports for the rail line sit. Including barriers, this is 11 feet more than the current 107-foot-wide viaduct, although it is not as wide as the proposed MassDOT viaduct with full shoulders. However, by mitigating the steep grades and sight line issues, the road could be designed in this section with these narrower shoulders. With 11 foot lanes, an 8 foot shoulder could be accommodated.
  • Six feet for the concrete pedestal supports for the box-girder structure for the Grand Junction rail line, which is 30 feet wide.
  • 30 feet for the Worcester Line right of way, which would be relocated only slightly once the viaduct abutments are removed.

From above, it would look something like this (with just a sketch of ramps and street grid in Allston, which would built above grade):

And a focus in on the narrow viaduct area:

It would also have benefits in the Allston area. In current plans, the Turnpike viaduct has to slope gradually down through the Beacon Park Yard area. If it were at grade, it could be easily decked over, and ramps could go up to a street grid on that deck. The Grand Junction would have to descend towards West Station, but it has a much smaller footprint and would start its descent from a lower elevation, thus it would much more easily integrate in to the surrounding area.

Construction would also be much simpler, because instead of a multi-stage process where the viaduct was unbuilt and rebuilt at the same time, it would simply be unbuilt in stages, with the new roadway built on the ground below. The current staging plans call for a new, wider viaduct to be built in stages, two lanes at a time, while the old bridge is being torn down, including many temporary supports and other engineering issues. By putting roadways at the surface, you could accomplish the entire task without building any new bridging, in fewer stages (dismantling four lanes at a time instead of two), and only shoring up a few supports temporarily. It’s even possible that pedestals for the Grand Junction—which would likely be built under the current viaduct before other construction—could be used during construction to shore up the viaduct as it is dismantled.

As for the final product, rather than a 110-foot-wide, 30-foot-high viaduct, you’d have a 30-foot-wide, 24-foot-high one. The rail structure would have just 22% of the mass of the road viaduct. Road noise would be lower to the ground (with the potential for an overbuild park to cap noise all together), and the viaduct would be further from the river and from buildings at BU. And ongoing maintenance costs would be far lower. The main loss is the inability to tuck some of Soldier’s Field Road under the viaduct and create slightly more parkland in the vicinity of the viaduct. But for a cheaper project, you get a much smaller viaduct which casts fewer shadows over this area, so the bike path is a more pleasant experience.

The only major issue would be a relatively long-term closure of the Grand Junction branch, so MBTA operations and a small amount of Everett-bound freight would have to move via Ayer and Worcester. This happened recently when the Grand Junction bridge was undergoing emergency rehabilitation for several months; the biggest issue was the 10 mph speed limit on Pan Am trackage between Ayer and Worcester. (The railroad out to Worcester is Class 3 and permits 60 mph speeds, the rebuilt railroad inbound from Ayer will mostly be Class 4 with speeds of 80 mph.) With a small portion of the money saved from not building a road viaduct, that track could be upgraded to Class 2 (30 mph) trackage to save considerable time with equipment swaps and improve a freight rail trunk line as well. It would also be an opportunity to fully rebuild the Grand Junction bridge, and other portions of the corridor to Kendall Square and beyond. (One other minor issue is serving Houghton Chemical, which could be accomplished, by relocating Houghton Chemical to the other side of the highway as depicted above. In the “armpit” of the Turnpike and railroad, it would be a perfectly good site for such a use, sustain a family business in the area, and free up developable land near the river.)

Once you take a step back from the current situation and think about this, it’s obvious. It makes no sense to build a wider, higher viaduct for a roadway when you can build a narrower and lower one for the railroad. All it requires is some grading underneath the viaduct, construction that is certainly no more complex that what is being proposed. A surface roadway has a much longer lifespan and lower maintenance costs than an elevated one, and it provides a much less obtrusive—and more future-proof, as it fits in better with potential development in Allston—structure as well. It’s a better project. Best of all, given the cost differentials for projects like the Casey Overpass elimination (and McGrath and Bowker), it could probably be built for $50 to $100 million less than the viaduct, with future savings from lower maintenance costs.

That money would go a long way towards full completion of this project, mitigation steps, and ensuring the safety of other roads and bridges across the Commonwealth.

Allston-Brighton toll straightening shouldn’t ignore Soldiers Field Road

Massachusetts has taken on a surprisingly progressive role in transportation policy in recent years, with the transportation secretary publicly stating that “we will build no more superhighways” and setting explicit goals for a shift away from single-occupancy driving. As part of this fix-what-we-have policy, the state is planning to convert the whole of the antiquated tolling system to open-road tolling, eliminating toll boots and charging vehicles based on transponders and license plates. This is a good step forward as it will not only reduce congestion at toll booths but also reduce the amount of land required by the serpentine ramps and plazas needing at Turnpike entrances and exits. While rural interchanges won’t be changed, it give the opportunity to rework a lot of urban land previously occupied by redundant roadways.

Nowhere is this more of an issue than at the Allston tolls in Boston. Here, the main trunk of the Turnpike loops around a now-disused rail yard, and a convoluted set of ramps feed on and off of it with four separate toll plazas. The state has announced a $260 million plan to straighten this interchange, which contains dozens of bridge spans in need of replacement. An early conceptual design has been announced that reduces the amount of land required and simplifies the roadways. While this is a good start, it ignores the space just beyond the interchange, namely, the confusing and dangerous interchange with Soldiers Field Road which is congested, a major impediment to bicyclists and pedestrians and which darkens a stretch of the Charles River with highway ramps and traffic jams.
Typical traffic.

The Turnpike-Cambridge/River Street-Soldiers Field-Western Avenue interchange is a royal mess. It is so confusing that the state long ago stopped maintaining lane markings, and today it is a free-for-all as vehicles jockey for position as ramps funnel in to each other at a series of lights. For bicyclists and pedestrians? It’s a nightmare. Coming east on Cambridge Street is nearly impossible through the traffic chaos, and even crossing Western Avenue and Cambridge/River Street on the Paul Dudley White Bike Path is difficult, without a specific bike/ped cycle, crosswalks, curb cuts or even, at the southern bridge, a walk light!

A bit of a radical idea here that I’m proposing would be to move Soldiers Field Road away from the River. From Boston to Watertown, nearly the entirety of the Charles River is lined by highways. Yes, there is a bike path squeezed in between the riverbank and the roadway, but it is clear that cars are given the priority—we’ve turned our back on the river. The bike path is narrow, and when it intersects roadways crossing amidst the turning vehicles, it is perilous. It is a poor excuse for bicycle infrastructure, yet it is quite heavily used. Added to this, Soldiers Field Road doesn’t even follow a straight line but hugs the riverbank, adding distance (and pollution) for motor vehicles.

Here, then, is a conceptual plan to both improve the Turnpike interchange and the connection between the Turnpike, Soldiers Field Road, Western Avenue and River Street. Just doing the first part will still result in backups, congestion and pollution, and do nothing to improve the lot of pedestrians or cyclists. This plan would improve conditions for all users, and while it would require a major buy-in from Harvard University (which owns the land Soldiers Field Road would be rerouted across), they would be given a major incentive: an Allston campus connected directly to the river (in fact, some of their long-range plans have included decking over part of Soldiers Field Road). Depressing and covering the road would be simple compared to many similar projects (i.e. the Big Dig) as it runs almost entirely through post-industrial brownfields and athletic fields, no major property takings or utility work would be necessary, and much of the route would be closed to trucks, meaning the road clearance would only have to be big enough for emergency vehicles (and, perhaps, transit buses).

I’ve annotated the map, each letter corresponds to a comment below:

Click to make big!

A: The eastbound Turnpike main trunk would be depressed below the westbound trunk, allowing ramps to overlay.
B: A single westbound ramp would allow access to Soldiers Field Road in both directions, as well as River Street in Cambridge. Western Avenue would be accessed via Soldiers Field Road. Note that if Soldiers Field eastbound were merged with the Turnpike (see below), these ramps would be mostly below-grade; it could be built to allow that sort of conversion at a later time.
C: Soldiers Field east mainline. These roadways, and the ramps on and off of them, would not require truck clearances (but would require clear “no trucks” signage).
D: Cambridge Street could be narrowed to 4 lanes, and narrower yet between ramps. Sidewalks and cycletracks could be elevated to avoid ramp entrances and exits. Traffic from Western Avenue to Cambridge Street via Memorial Drive.
E: Offramp to Cambridge Street would end at a traffic signal.
F: Elevated cycletrack / sidewalk allows cyclists to avoid traffic signal and on/off ramps.
G: River bike path built 12+ feet wide, utilizes one of the disused Soldiers Field underpasses to avoid grade crossings. This would allow a 8-mile traffic-free trip from the Charles River dam west to the Western Avenue Bridge in Brighton by foot or bicycle. The other side of these underpasses would be filled.
H: Separated cycletrack facilites on the Western and River/Cambridge bridges would connected with the grade-separated riverside bike path. The riverside path could be set back from the riverbank, which would be maintained for active and passive recreation.
I: Rebuild the Weeks Bridge with ADA accessibility, and connect to bike paths for a river crossing.
J: The connection between Soldiers Field Road and the Eliot Bridge would be grade-separated; the current connection has a three-phase light in the center. Another option would be a single-point light between the Soldiers Field East-Eliot Bridge and Eliot Bridge-to Soldiers Field East which would reduce grade separation.
K: The current underpasses under the Eliot Bridge for bicyclists and pedestrians would be retained. Sidewalks / paths on the bridge would be used for grade-separated access to south-side pathways.
L: Most of the intersection east of the Eliot Bridge would be rebuilt as a wide swath of parkland.
M: A bicycle bridge would be built across the Eliot Bridge connection, cutting some distance off this route. Grade-separation would be integrated with the Eliot Bridge, and the current Eliot Bridge underpass would be retained (K).
N: Ramps to the current elevated structure would be built not to preclude future grade separation eastbound.
O: Mixing zones on Soldiers Field Road would be three lanes wide, and long enough to allow traffic to merge across two lanes to access various routes (although engineering would be required to determine the optimal length here so as not to bottleneck).
P: Ramps to Western Avenue would be built to specifications for truck traffic; north of this it would be cars-only. Traffic destined to Harvard Square would be routed west on Western and then east on Harvard, or via Memorial Drive.
Q: Ramps at North Harvard Street would be offset to keep construction away from Harvard Stadium. The track would be reoriented after construction.

While adding Soldiers Field Road reconfigurations to the rebuilding of the Turnpike interchange, the project should still not be viewed in isolation but rather as part of the larger transportation network. A few things to consider:

  1. Allowances should be made for future fixed-guideway transit between BU and Harvard.
  2. The entirety of the Turnpike, the railroad tracks and as many ramps as possible could be buried to allow the street grid to be connected across the rail yard from the BU area towards the river.
  3. Instead continuing east along the river, Soldiers Field Road could merge in to the Turnpike. This would require a wider highway (perhaps five lanes in each direction) and require the highway to be rebuilt below-grade to allow for room for the rail line. It would probably also necessitate some sort of exit in the Charlesgate area. This would be moving towards Big Dig territory as far as complexity, although by moving all rail service to North Station via Cambridge on the Grand Junction, enough space could be freed up to phase construction along the Turnpike. It would, however, create a three-mile-long section of riverfront with no roadway between the city and the river. (Paul Levy made this point years ago.)
  4. The Grand Junction, if (3) were built, would have to be fully rebuilt, below grade and with a transfer station at Kendall Square, although this would be a dramatic transit enhancement for the region and worth the investment.
  5. If Soldiers Field Road and Storrow Drive beyond it were replaced, it would recreate the parkland which James and Helen Storrow originally intended along the river. A two-lane parkway-type road could be retained from Charlesgate (which would have the Bowker Overpass flyovers removed) eastward (although this, too, could be in a tunnel) with a wider roadway resuming only past the current tunnel near the Hatch Shell towards Leverett Circle.
In other words, a project as large as proposed for the Allston Tolls should not be viewed in isolation, as its effects—good or bad—will cascade in several directions along the transportation network. With this kind of brownfield, simply rejiggering some onramps—and ignoring nearby bottlenecks and queues—is not enough.