Bus Lanes on the Harvard Bridge

April was Bus Month here at Amateur Planner, and May is showing no signs of slowing down. I noticed recently that in a traffic jam on the Harvard Bridge (which occur regularly, especially during baseball season), there are not many buses on the bridge, but they carry a large portion of the people crossing it. So I waited for the next traffic jam on the bridge (not a long wait) and went to take a photograph, which I then annotated:

This was taken at the 250 Smoot marker (so about two thirds of the way to hell), and I noted that, in stopped traffic, there were 20 cars per 100 Smoots (this is a bit more than 25 feet per car; Smoot markers make it really easy to quickly measure things). I took a quick census of the number of people in each car (appeared to be about 1.3) and set about making the graphic above. (The bus numbers account for one at all-seated capacity, one at normal standing capacity, and one at crush load.)

Then I tweeted it, and it may have gotten retweeted a couple of times.

There was one bizarre (in my opinion—and I'm really not sure if it's uninformed or malicious) response thread, which amounted to the following (as requested by the Tweeter, the full conversation is below):

This is where the bus does go. (1/4 and
1/2 mile buffers of MBTA bus routes.)
So, pretty much everywhere.

Responder: Plenty of people need to get where buses don't go.
Me: I'm fine with them having one lane of the Harvard Bridge, and the buses go a *lot* of places; if they ran faster than cars, more people would take them.
Responder: So glad you're not making the rules.
Me: Here are areas within 1/4 and 1/2 miles of bus routes, where again are people going that the buses don't go? [See map at right.] And why should my tax $$ go to pay for buses to sit in traffic so cars can … sit in traffic? >50% of the people on the bridge are in buses. Why not give them 50% of the space?
Responder: It's the when, not the where. Bus schedules don't nec. match ppl's schedules. RedSox fans all over NE. [editor's note: see original Tweet in thread.]
Me: So if the buses were 15 minutes faster than driving, people would take them, and anyone who *drives* to Fenway deserves a dope slap. [There's] plenty of parking at Alewife-Riverside-Wellington-Wonderland. Trains run every 5 mins. Why should 20k+ bus passengers be delayed 10 mins for a few Sox fans?
Responder: It's about making connections too—when too many connections get inefficient, driving works.
Me: Driving works? Tell that to the people on that bridge: people were walking faster. Bus lanes means more people opt for transit, fewer cars overall, and less traffic.
Responder: Just because buses work for you doesn't mean they work for all.
Me: That's the problem. They don't work. The deck is stacked in favor of driving. I'm not saying ban cars, I'm saying let's equalize street real estate. Why shouldn't a bus with 50 passengers have priority over a car with 1 or 2?

But this is the usual reactionary inability to see the greater good. Take away a lane from cars, and it's an affront to driving. An affront to freedom. Un-American. Never mind the majority of people on that bridge aren't driving cars. They don't matter. Still, I haven't heard this turned in to an equity argument, so that's kind of groundbreaking.

So the first part of this blog post is a plea: Ms. Cahill, I want to know what goes through the mind of someone who can't see that transit efficiency is a societal benefit, and that it will amount to more people using fewer vehicles. Please email me, comment here, and discuss. I want to know.

The second part is me, trying to quantify what would happen to vehicles displaced by a bus lane on the Harvard Bridge, and what the time savings would be for bus riders as opposed to the time penalties for drivers. And, as I am wont to do, I did this in chart form. I imagined a hypothetical traffic jam stretching across the bridge (0.4 miles) in a closed system where all of the cars feed off of Mass Ave on to the bridge (this is close to the case, but some traffic does enter from Memorial Drive):

At first glance, going from two lanes to one would double the length of roadway needed to store the same amount of cars. But several other factors come in to play. First of all, the buses take up the space of 8 cars—at least. Then, we can assume that 10% of the cars remaining will shift modes: if taking the bus is all of the sudden significantly faster than driving, people will use it. And people in taxis (by my estimation, 10% of the traffic on the bridge) will likely switch in greater numbers since they're starting closer by: I estimated 50% mode switch there. Then there's induced demand: make the traffic on Mass Ave worse, and some drivers—I said 10%—will choose another route, whether it's the Longfellow or the BU Bridge or further afield.

Add these together, and I would guess that traffic would increase by between 1/3 and 1/2. Assuming that traffic moves at 5 mph, this would mean an increase of 2.5 to 4 minutes for each person in a car on the bridge. But it would also mean that buses would cross unencumbered by traffic, making the trip in one minute, and saving every bus passenger 7 (this assumes that the bus lanes extend back to Vassar Street, displacing bus stops and a few parking spaces on Mass Ave through MIT). With these numbers, drivers would incur 510 minutes of additional delay, but bus passengers would save nearly three times that much time—a dramatic benefit.

Am I way off base with these numbers? I don't think so. When the Longfellow went from two lanes to one, vehicle traffic decreased by nearly half! Traffic spread to other locations, people chose other modes (walking, biking, transit), or didn't make trips. The traffic apocalypse that was predicted didn't materialize, and life has gone on.

The Harvard Bridge is one of the most heavily-traveled bus corridors in the city, up there with the North Washington Bridge, the Silver Line on Washington Street, the 39/66 concurrency on South Huntington, portions of Blue Hill Avenue, some streets to Dudley and the feeder buses to Forest Hills. (All of these should have bus lanes, by the way.) The 1 and CT1 combine for more than 15,000 trips per day and, at rush hour, better than one bus every 6 minutes. The bridge also carries the heavily-traveled M2 MASCO shuttle 6 times per hour. Combined, these routes account for a full (usually crush-load) bus every three minutes—which is why in a 10 or 12 minute traffic jam there are three or four buses on the bridge at any given time—transporting at least 1000 passengers per hour.

Bus lanes would allow these bus lines to operate more reliably, more efficiently and more quickly, meaning the same number of buses could run more trips, and carry more people. Which, if they're 10 minutes faster than cars, they're going to be carrying! This would be something that could be tested and quantified, and it could be done as a temporary pilot with cones and paint. There is no parking to worry about, no bus stops to relocate: just set aside one lane for buses (and give buses signal priority at either end of the bridge). This would take the cooperation of MassDOT, DCR, Boston and Cambridge—and prioritize "those people" riding transit over real, taxpaying non-socialist Americans—so I don't expect it to happen any time soon.