Tuesday, August 16, 2016

The problem with the CT1

The 1 bus is one of the busiest routes in Boston. It runs along Massachusetts Avenue, touches three subway lines (and the Silver Line), and is an important crosstown route, despite frequent bus bunching and traffic delays. The bus is chronically overcrowded; I've regularly counted 78 people on a 40 foot bus, even with frequent service. It is supplemented by the CT1 "Limited" service route, but the CT1 is poorly planned and integrated, and winds up being a waste of resources on the route. (Speaking of resources, we've argued in the past that the corridor should have bus lanes on the Harvard Bridge and in Boston, with a more equitable allocation of space for corridor users.)

The CT1 is barely a limited service route. The two routes overlap between Central Square in Cambridge and BU Medical Center in Boston. In theory, the CT1, by making fewer stops, should be able to make the trip significantly faster than the slower 1 bus. What follows is an exhaustive list of stops that the 1 bus makes that the CT1 bus does not:
  • Mass Ave at Albany Street
  • Mass Ave opposite Christian Science Center
  • Mass Ave at Columbus Ave
That's it. 

In general, a limited stop route should serve no more than half the stops that the local service does. (For instance, limited-stop routes in Chicago make only about one in four stops the local buses serve; the Twin Cities is similar.) But in this case, the local route makes 13 stops, and the limited route makes 10. A few years ago, several poorly-utilized stops on the 1 bus were cut. (This included the particularly inane stop in the median of Commonwealth Avenue which required crossing the same number of streets as stops within a few hundred feet at Beacon and Newbury. The stop at Columbus Ave is within 500 feet of the Mass Ave Station and could be similarly consolidated. For those of you keeping track at home, that's less than a two minute walk.) If most of the stops are served by both buses, there's really no point in having the two separate routes overlap and not make the same stops. Cut Columbus and consolidate Sidney and Albany in to one mid-block stop and you can have both buses make the same stops.

Not that anyone really waits for the CT1, anyway. Passengers, for good reasons, generally will get on whichever bus comes first unless the next is visible. If a 1 bus pulls up, get on the 1 bus; it's rare for it to lose so much time at two or three stops that it gets caught by another. The CT1 is really more of a short-turn of the 1 bus (the inimitable Miles on the MBTA agrees as to its lack of usefulness), serving the busier portion of the route between Boston Medical Center and Central Square. Yet the schedules aren't integrated, so, at times, two buses are scheduled to leave Central Square within a couple of minutes with a subsequent 10-plus minute gap. 

For visual learners, this chart shows the combined 1 and CT1 bus headways
at Central Square, and a moving average of five buses. By combining the
1 and CT1, the effective headway could be reduced significantly. In other
words, the orange line shows the average headway of the bus (what would
be possible if the routes were combined and better dispatched) while the dots 
(blue and orange) show the effective headway of service provided today.
What this creates is a situation where resources go underutilized. Often a bus will leave Central Square packed to the gills, and another will leave mostly empty two minutes later—and invariably catch up with the bus in front of it—and then no bus will run for 10 minutes. Yet if the two routes were combined, rush-hour service could be provided every seven minutes (down from wait times as long as eight minutes in the evening and ten in the morning) at rush hours and 10 to 12 during the midday (current wait times are as long as 15 minutes midday). Currently, the 1 bus uses 7 to 14 vehicles depending on the time of day, and the CT1 either 2 or 3 (data from the Blue Book). Reassigning the CT1 vehicles to the 1 bus would reduce the headways from 9.5 minutes to 7.5 minutes at morning rush, 14 to 11 minutes midday, and 8 minutes to 7 minutes in the evening (it's possible it may be better since there would be less bunching delay to require more recovery time). This is somewhat related to the poor interlining of the 70 bus which this page has discussed in the past. The effective headway of the bus—the longest headway during any given time—is longer than it would otherwise be. 

Last year, through Cambridge's participatory budgeting system, voters there overwhelmingly supported signal priority for the 1 bus, and, according to Twitter, it is currently being installed. This is important, as it will allow better schedule adherence for buses which otherwise get hung up at the many lights through the city (traffic, on the other hand, is another question this page will attempt to answer in coming days). Better dispatching is important as well to allow short turns when two or three 1 buses run back-to-back (which happens all the time).

The CT1 may have made some sense when the 1 bus made more stops, but today it just serves to gum up the works. After 22 years, it's time to axe the CT1 and improve the 1 bus. Relieving the route of a few extraneous stops was a good start. Cambridge has taken another step forward with signal priority. All-door boarding and pre-payment would be easy at major stops, since most are adjacent to stations with fare machines (and others, like MIT, could have machines installed). Loop Link-like platforms and stations would help as well (Loop Link is an example of where the city and its transit agency actually talk to each other). And dedicated lanes? Well, that's probably further off, but should be part of an iterative process. Otherwise, we'll waste most of the small, but important, improvements to the 1 bus so far.

2 comments:

  1. I take this bus (well most of the time I end up walking) from Hynes to Mass ave/Vassar intersection. One thing I noticed is that in the morning as I am walking from Hynes station towards cambridge I see many Ct-1/1 going in the opposite diretion and exact opposite in the evening. Shouldn't they adjust the rush hour schedules in such a way it helps commuters going to/from work? lots of traffic delays once they enter cambridge can be attributed to the MIT walking signal at 77 mass ave which seems to turn red every couple of mins - ideally they should build an overhead walkway there.

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  2. Back when I had a subway-only pass, I could ride the CT1 but not the 1, so there was more of a distinction, though I was always pissed that it ends at Central.

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