Comments on Inman Square Public Meeting
June 24, 2016
On June 22 Cambridge held a public meeting on traffic in Inman Square. I did not attend. I did receive a pointer to the presentation. The next day, a woman on a bicycle was killed in Inman Square, perhaps first doored, certainly run over by a landscaper’s truck.
Slide 4, I see counts of “traffic volumes” measured in “vehicles per day”.
Which of the following is “vehicles”:
- bicycles only?
- cars and trucks only?
- bicycles and cars and trucks?
I see no pedestrian counts, which seems like a major omission.
I also see no breakdown by turns, which makes it difficult to know how much of a priority to place on turning traffic.
I also don’t see any information about existing light timings.
For slide 13, the only group for whom “increase efficiency” is a concern is “Vehicle”, and I suspect that really means “Motor vehicle” since “Bicycle” is a separate category. This seems like a major omission, since you have apparently not measured either the bicycle traffic or the pedestrian traffic, we don’t know if optimizing motor vehicle efficiency reduces the total time wasted at this intersection, and it might well compromise safety. Lacking any other information, I think we must assume that each person traversing this intersection is equally important.
It’s also important to notice that attempts to “increase efficiency” for motor vehicles here could be pointless. This intersection doesn’t exist in isolation; it is connected to the rest of Cambridge, which is also filled with traffic jams. In contrast, both bicycles and pedestrians flow freely through the rest of Cambridge (I bicycle commute on Broadway or Hampshire every working day of the year, I have video) so impediments removed here would result in actual gains.
One efficiency problem that could be addressed with no infrastructural changes is locally-greedy misbehavior by drivers; people frequently enter the intersection without a clear path to exit it, resulting in a blocked box when the light changes (bicycles are less affected by this; again, I have video). Drivers also speed fruitlessly (later to be passed in a line of stopped traffic by a fat old man on a huge heavy bicycle, so truly useless speeding), endangering everyone. In both cases, the remedy for locally-greedy misbehavior is enforcement; tickets for blocking the box, tickets for speeding, tickets for running red lights. Automated enforcement is probably more cost-effective than staffing the intersection every day at rush hour.
Another thing I saw no mention of was the role of parking in reducing safety. The door zone is a constant worry to cyclists, and the space allocated to parked cars also reduces options for creating safe places for cyclists to ride.
Other questions that need answering:
- I know that buses use Hampshire. How many people use those buses, and how much delay (summed over all the bus passengers) results from that delay? That’s another thing we should optimize.
- There’s a lot of bike traffic on Hampshire, especially at rush hour. If we knew the range of trip distances for people traversing Inman Square in cars (especially at rush hour), we might get some idea of the potential number of bicycle commuters that would use Inman Square if were less dangerous and more pleasant (it is one of the more significant unpleasantness bottlenecks in Cambridge).
Given what looks like a severe case of car-centric tunnel vision by whoever prepared these slides, I think that someone needs to start over again, perhaps doing the mental exercise of banning cars and seeing what sort of intersection results. (That’s not quite a serious proposal for an intersection design, but it is definitely a serious proposal for being sure that something other than cars-cars-cars is considered.)
My choice for a starting point would be to de-emphasize traffic “efficiency” for single-occupancy vehicles since those are the least-efficient users of scarce road space, the most needy in terms of a clear path to travel, and relatively dangerous to other people on the roads. Buses are space-efficient, very safe for their passengers, necessary for the less-able, and a good backup choice in nasty weather. They’re not a good thing to crash into, but their drivers are trained professionals, and risk-to-others is amortized over all the passengers on the bus and thus is not that large per passenger. We should remove enough cars from the road to ensure that buses are not impeded. Both bicycles and pedestrians are very space-efficient and though neither mode is risk-free, they are very safe for other people, and they’re also able to cope with narrow paths and impediments that completely block automobiles. I would therefore do as much as possible to make those two modes attractive. When I look at all the somewhat-unused space in Inman Square, my reaction is to try to find ways to use that space make things better for pedestrians and cyclists, instead of trying to use it as more places for cars to drive on.
Videos of Inman Square: