Tag Archives: longfellow bridge

Is a part-time bike lane appropriate for the Longfellow?

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So far in our irregular series on the Longfellow Bridge we’ve looked at the difficulty accessing the bridge from the south, the usage of the bridge compared to the real estate for each use and how many bikes are actually using the bridge at morning rush. While my next step is to actually go out and count bikes (maybe this Thursday!), I’ve been thinking about what sort of better inbound bicycle infrastructure could be implemented for the bridge.

Here’s a graphic. I’ll make more sense of it below (Click to enlarge):

Here are the issues at hand:

  • Peak bicycling occurs between 7:30 and 9:00 a.m., when bicyclists traveling from Cambridge, Somerville, Arlington and beyond converge on the Longfellow to commute to work in downtown Boston. For nearly any destination in Back Bay and Downtown, it is by far the easiest access.
  • There is much less cycling outbound at rush hour because of mazes of one-way streets combined with heavy vehicular traffic on the other access roads (i.e. Cambridge Street).
  • Thus, the highest bicycle use at any time on the bridge is during the morning rush hour inbound, but while plans indicate a wide, buffered bike lane going outbound, the inbound lane will barely be widened.
  • Since the bridge has a noticeable incline from the Cambridge side, there is a wide spread of cyclist speeds, and it is reasonable to expect cyclists to want to overtake during heavier use times.
  • With improvements to Beacon Street in Somerville as well as the access through Kendall Square, even more cyclists will crowd the bridge in the morning.
  • With the expansion of Kendall Square and its reliance—to a degree—on bus shuttles, it can not be allowed to gridlock over the bridge during peak periods (generally evening rush hour).
In other words, bikes need more room in the morning. And cars need more room in the evening (a single lane on the Longfellow would only accommodate somewhere along the lines of 50 vehicles, and might quickly queue in to Kendall). Luckily, these needs are not necessarily mutually exclusive, and a part-time bike lane would be a possible solution to give bikes the room they need at peak times, while not piling traffic in to Kendall at other times.
In general, part-time bike lanes have been created when parking is allowed at some times and not others (here’s an example from the Embarcadero in San Francisco). The Longfellow is unique in that it has dramatically different usage rates between motor vehicles and bicycles (there are probably twice as many bikes in the morning than the evening, and twice as many cars in the evening than the morning). Bridge real estate is obviously limited—in a perfect world there would be two lanes for traffic and a wide, buffered bike lane, and a pedestrian promenade. So it would be a engineering, logistical and educational challenge to implement such a program.
Here’s the thing: the bridge will be effectively shut down for three years. Traffic will be shifted around for long enough that drivers won’t well remember the previous infrastructure, so it would be a good time (perhaps the only time) to try something drastically new. Here’s a sketch of an idea:

Between Kendall Square and Memorial Drive, Main Street will merge from two lanes to one, to the left. The right lane will be for turns on to Memorial Drive only, and will be set off from straight-ahead traffic with bollards or a median.

Past the Memorial drive ramps:

The left inbound lane is kept at 11 feet and all non-Memorial traffic merges in to it before the bridge. The constriction for the Longfellow traffic is throughput at Charles Circle, so this shouldn’t dramatically affect traffic, especially since Memorial Drive traffic would exit in a dedicated lane. This will allow traffic to comfortably travel in it at all times. The lane would be signed as Vehicle Traffic, All Times. It would be separated from the right lane by an unusual marking such as a double broken white line. 

The right inbound lane should be narrowed to 9 feet in width. Height restrictions (chains hanging from an overhead support) could be hung at intervals to discourage trucks and buses but signage would likely suffice. It would be signed as Bikes Only Except Weekdays 3 PM to 7 PM. No Trucks or Buses. It would be marked with diamonds or some other similar feature as well as “Sharrows” and separated from the bike lane by two solid white lines with no painted buffer in between, potentially with infrequent breaks.  

The bike lane would be 6 feet wide and the two lines would serve as a 2 foot buffer at evening peak. It would be signed as a regular bike lane.

This will extend to the top of the bridge where the grade evens. Beyond that point, there is less need for a “climbing lane” for cyclists, and the bike lane will taper to one, buffered lane. The left lane stay 11 feet, and the right lane 9, but it will be open to cars at all times, with a continued buffered bike lane. Having the right lane closed to trucks and buses will dramatically increase the comfort level for bicyclists who are often squeezed by large vehicles, who will have no business in the right lane.

At the Cambridge End of the bridge, the merge to one lane before the Memorial Drive will funnel all Cambridge-origin traffic in to the left lane (this is the only origin for trucks and buses which can not fit under the Memorial Drive bridges). During non-peak afternoon hours, the Memorial Drive intersection would then join this traffic in a short merge lane after crossing the bicycle facility. At peak hours, it would continue in the right lane. This means that for a truck or bus to use the right lane, it would have to actively change lanes, meaning that even during rush hour, bicyclists would not be pinched by frequent tall tour buses and delivery vehicles. And at other times, most of the origin traffic from Cambridge would already be in the left lane, and only the Memorial Drive traffic—which already stops at a stop sign—would have to be signed in to the lane based on the time of day. The irregular lane markings will clue most drivers in to the fact that there is something different about the bridge, as will signage placed on the bridge approaches.

At the Boston end of the bridge, just before “salt/pepper shaker” the bridge could be widened (for instance, see this older image) to allow bicyclists to stay in a buffered bike lane and cars to sort in to three full (if narrow) lanes. However, two lanes might be preferable to allow trucks and buses to get from the left lane on to Charles Street (or such vehicles could be forbidden from this maneuver and forced straight on to Cambridge or left on to Embankment Road). In this case, enough room for side-by-side cycling in a bike lane—at least 7 or 8 feet—should be allowed (this is not showin the above schematic).

The potential for a flyover bike ramp to the unused portion of Embankment Road should not be discounted, either, as it would siphon much of the bicycle traffic away from the congested Charles Circle area. I called this the “Gateway Overpass” as a lower, gentler and wider bridge could span from the Embankment Road area across Storrow Drive to the Esplanade and allow easy egress to Charles Street across the Storrow offramp. The current bridge is narrow, steep and congested, and provides far more clearance over Storrow Drive than necessary. A new bridge is proposed (see page 10 of this PDF) but I think a level bicycle facility would be very helpful to help bikes avoid the congestion at Charles Circle.

If this project were found to be either dangerous for cyclists or a major impediment to traffic in Cambridge, it could be changed simply by restriping existing lanes, so there would be no major cost involved. If it constricted traffic enough, the lanes could be restriped with a buffer to allow a wider cycling facility inbound at all times.

I think it’s worth study, if not a try.

Longfellow Bike Traffic update

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I came in this morning across the Longfellow. As I jockeyed for position through Kendall, I knew it was going to be busy on the bridge. I’ve seen ten bicycles per light cycle on the bridge, but today the lane was chock-a-block with bikes all the way across the bridge. With minimal auto traffic, faster cyclists were swinging in to the right lane and passing slower cyclists. And when we got to the bottom, well, it was quite a sight.

I quickly hopped the sidewalk to take a picture. By my quick count, there were 18 cyclists in line waiting for the light to change at the bottom of the bridge. Last month, I’d assumed 10 bicyclists per light cycle, which would equate to 360 per hour. At 18 bicyclists, this is an astounding 648 bicycles per hour, or one every six seconds. That’s nearly as many vehicles as use the entire bridge in the AM peak (707). And this is despite the fact that the Longfellow is a narrow and bumpy bicycle facility.

So it is a shame that the current plan for the bridge allocates just as much space to vehicles, and does not appreciably expand the inbound bicycle facility. As we crossed today there were few vehicles, but bicycles could barely fit in the lane. Since the bridge hasn’t been rebuilt yet, there is still time to advocate for fewer vehicle lanes (one lane expanding to two would be mostly adequate) and a much wider bike lane allowing for passing and a buffer.

The current bicycle counts are only for the evening commute where, as I’ve pointed out before, it’s much harder to get to the Longfellow due to traffic, topography and one-way streets. I think it’s high time for a peak morning bike count on the Longfellow. And time to suggest to MassDOT they reexamine the user base for the roadway before it gets reconstructed and restriped.

Plus, if we have 650 bikes per hour using the current, subpar facility, imagine the bike traffic once the lane is wider and well-paved. To infinity and beyond! Or, at least, to 1000.

Longfellow Bike Traffic

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I usually cross the Longfellow Bridge by bicycle around 7:30 a.m. It’s before the peak of the rush hour, and while I’m not alone on two wheels, it’s not too crowded. Twice this week, however, I’ve been crossing the bridge eastbound around 8:30. And both times, when I’ve reached the light at the end of the bridge, there was a veritable traffic jam of bicyclists, with a lineup of 10 two-wheelers waiting to turn right on to Charles or go straight up Cambridge. We’ve had a long string of great cycling weather (sunny, dry and cool), Hubway is in full swing, and we’re recovering from the marathon fiasco. So there are a lot of bicyclists.

From this small sample, I’m going to make some big extrapolations. I sleuthed out the traffic counts from the intersection from a Red Line / Blue Line connector document (pdf) and sussed out that it is a 100 second light cycle—that it repeats 36 times per hour. Assuming a constant ten cyclists per light cycle for an hour, this would equate to 360 bicycles across the Longfellow in an hour. Is this a big number? I think so. Here’s why:

  • This is more than half as many bicyclists as vehicles. Peak morning eastbound car traffic is 707 vehicles per hour. Now, the Longfellow is mainly a transit bridge, and at peak hour the Red Line carries more than 10,000 vehicles. Plus, vehicle traffic decreases (as it has in the Kendall area) and bicyclists’ numbers continue to climb.
  • Bicyclists have a sub-optimal facility on the Longfellow. In other words, the bike lane kind of sucks. It’s bumpy, narrow and squeezes down at the Boston end of the bridge (although it is better-paved there). The future lane will be a bit wider, although to preserve two lanes of inbound traffic it won’t have a buffer built in. Still, it won’t be as squeezed as it is now. (MassDOT pdf)
  • This illustrates the importance of keeping the bridge open to cyclists during construction, as is the plan. Even as traffic is limited to one direction, bicyclists and pedestrians will be allowed to cross the bridge in both directions. With hundreds of bikes per hour, it’s a vital link in the regional bicycle infrastructure.
  • Finally, the roadway is currently more efficient at carrying bicycles than motor vehicles. 707 vehicles use two lanes per hour, at a rate of 354 per hour. Bicycles use one lane, and there are (by my assuredly crude calculations) 360 bicyclists. But wait! Aren’t traffic lanes a lot wider than bike lanes? Yes. 360 bicyclists traverse the Longfellow in only 5 feet of bridge width, at a rate of 72 vehicles per foot. The 707 cars have 24 feet of bridge width, a rate of only 29 vehicles per foot. Even if we assume 1.25 people per car, bicycles are still twice as efficient at transporting people. (And, yes, the Red Line inbound, in 14 feet of bridge width, transports more than 10,000 people, making it ten times as efficient as the bike lane.)
Of course, the bike lane is certainly not at capacity (neither are the vehicle lanes; although the Red Line is quite crowded). Leaving two lanes for vehicular traffic in the new bridge design is contentious, and a single-lane design with a wider, buffered bicycle facility—akin to the outbound side of the bridge—would do more to encourage cycling. Even narrower lanes—and a wide bike lane—would help cyclists (and slow speeding motorists, as well). But even without that encouragement, bicyclists don’t seem to be shunning the Longfellow.

Chinatown to Charles: the Bermuda Triangle for bikes in Boston

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When I bike to work, my route is simple. I head down Main Street in Cambridge, cross the Longfellow Bridge, and take a right on to Charles Street. I go diagonally across Beacon Street on to the Common, bike down the wide bike path there, and then bike half a block (or, if I’m on a Hubway, a whole block), slowly, down a sidewalk to the office. It’s simple, relatively safe and even pretty fast.

On the way home, I don’t even bother to try the reverse. It is damn near impossible to get from the Chinatown/Theater District/Park Square area to the Longfellow Bridge, and the options are dangerous and annoying enough that I wind up on the Commonwealth Avenue bike lanes to the Harvard Bridge to Cambridge, a less direct, but much safer route. As such the inbound and outbound portions of my ride are, except for half a block of Mass Ave in Cambridge, completely different.

But what about when I have to go to Kendall? There are several options for getting to the Longfellow, each of which has some major bikeability issue. The main issue is that Charles Street is one way, with no provision for cyclists going northbound. It’s sidewalks are narrow and riding contraflow is a death wish (oh, and it’s illegal). Beacon Hill—the neighborhood it traverses—is comprised of one-lane, one-way roads, and they have been signed in such a way as to prohibit through traffic, which is sensible since it was laid out way, way before cars were invented. This would be fine, but there is no parallel to Charles Street. To the east is Storrow Drive. To the west is Beacon Hill. There’s no good way to get the third of a mile from the Common to Charles Circle.

I’ve gone through the options (none of them good) and rated each from 1-5 for three categories: bike-car safety (how safe is it in spaces shared with cars?), bike-ped safety (how safe is it on spaces shared with pedestrians?) and bikeability (is it really annoying to bike?):

The Storrow double-cross is what you get if you ask Google Maps. It’s a pretty bad suggestion. The two crossings are coded as bike lanes, and while they do provide traffic-free crossings of Storrow Drive, neither is bike friendly, at all. To get to the bridges, you first have to cross four lanes of traffic on Charles Street, without the benefit of lights, unless you dismount and use crosswalks at the corner of Charles and Beacon. The path on the north side of the Public Garden is not bikeable. I call this the Beacon Weave. It’s not much fun on a bike.

And all that does is get you to the bridges. The first crossing (1) is the Fiedler Bridge near the Hatch Shell. To gain altitude, it has two hairpin turns on each approach, the bottom of which is completely blind. Biking at a walking pace, or walking altogether, is necessary going up and down this bridge, which often has heavy foot traffic. Assuming you navigate that bridge, you get a couple hundred yards of easy riding before you have to navigate another double-hairpin bridge (2) to get back across Storrow. This one is less blind than the Fiedler, but it’s narrower and just as trafficked. Even then, that only gets you to the far side of Charles Circle, where you have to jockey in traffic turning off of the Longfellow and on to Storrow before you can get to the bike-laned regions on the bridge itself. This require four separate crosswalks or some creative light-running.

This route would be a bit more doable if there were a path from the river bike path to the Longfellow. But there’s not. It’s pretty nasty.

Verdict:
Bike-car safety: 3
Bike-ped safety: 1
Bikeability: 0
Grand total: 4

The Beacon Hill Stumble-Bumble is probably the most direct route, but it fails for a variety of reasons. Mainly, it involves going down several one-way streets the wrong way, which causes Google Maps to say things like “walk your bike” in the directions more than once. Plus, these streets are steep, narrow and have blind corners. It might be fun if you are a bike messenger, but if you value your life, it’s a pretty bad option. If a car comes the other direction, there is not enough room to pass with any degree of comfort and safety. And the streets are designed to not let you through, so if you don’t know your way, you’ll wind up lost and spit out on to Charles, Beacon or Cambridge Street anyway.

Verdict:
Bike-car safety: 1
Bike-ped safety: 2
Bikeability: 0
Grand Total: 4

The Beacon Hill Crossover is another Google Maps suggestion, and it’s slightly better than the first. It has you cut across the Common (or you can go around on Beacon), climb Beacon Hill, and descend on Bowdoin Street. That part of the route, aside from the hill climb, is not too bad. Then you hit Cambridge Street. Outside of rush hour, this isn’t that bad. During rush hour, this backs up off of Storrow Drive, and to get to the Longfellow you have to slalom slow-moving cars, and then get through the intersection at Storrow. There, it behooves you to find the left-most lane, because most of the traffic is turning right on to Storrow with no idea that a bicyclist might be going straight. Charles Circle is bike no-man’s-land (no-bike’s-land?) and it is several heartbeats before you are in the relative safety of the bike lane on the bridge. Oh, and there are always hordes of pedestrians running across Charles Circle to get to the T stop. A variant of this route via the less-hilly but longer and more-pedestrian-mall Downtown Crossing, which scores similarly, is shown as well.

Verdict:
Bike-car safety: 1
Bike-ped safety: 1
Bikeability: 3
Grand Total: 5

The Storrow Shortcut is the route I actually use. It isn’t pretty, but it certainly gets the job done. The main issue is that it requires either biking a narrow, decaying sidewalk along Storrow Drive or, more comfortably, actually biking down Storrow Drive itself! Google doesn’t realize that Storrow is not officially closed to bikes, and that there is a sidewalk along that route, so I can only show this route in driving directions. And, no, it’s not as crazy as it sounds.

On the few hundred yards of Storrow I bike, the road is three lanes wide and it has a narrow-but-painted shoulder line. It’s definitely better than the rutted-and-cracked sidewalk. Traffic is usually very slow there in the afternoon, and I can usually glide past the gridlock for the couple of blocks up towards the T stop. Once there, I hop on to the sidewalk and the unused part of Embankment Road and then under the bridge before hooking a left towards Cambridge. It avoids one-ways the wrong way, it misses the thick of the pedestrians, and it requires a minimum amount of weaving through traffic (but doesn’t miss the Beacon Street Weave). It’s ugly, but it works.
  
Verdict: 
Bike-car safety: 1
Bike-ped safety: 4
Bikeability: 2
Grand Total: 7


All of this, of course, could be solved with a two-way cycle track on Charles. This has been proposed, but has not seen any steps taken towards actual construction. Charles is three lanes of traffic and parking on both sides. Its shops are mostly pedestrian-oriented, and it probably doesn’t need this parking, but taking it out would cause an uproar. However, the street would, and should, function perfectly well with two lanes. And such a lane would funnel Cambridge-bound traffic from the Back Bay across the Theater District and Chinatown to the Financial District and even the Seaport. It would be well used.