The term “transit signal priority” (TSP) doesn’t sound too exciting; It’s a rather forgettable phrase. Easier to get excited about bike lanes, car share and Hyperloop as new transportation ideas than TSP. But, after a few months of becoming familiar with the idea, I now see why TSP and dedicated transit lanes are key to improving urban mobility today. When I talk about efficiency, I am referring to people’s time, pocket books, and energy use. According to TransitWiki: “TSP are operational improvements in the public transportation infrastructure that reduce dwell time at traffic lights for transit vehicles by holding green lights longer or shortening red lights.” In other words, Buses and trains get their own lights, with their own timing.

From what I’ve gathered, TSP exists in Boston in two parts of town: along several intersections of the Silver Line Bus route and at four intersections of the Bus 57 route. But the impact of TSP on bus service in these areas is minimal as the lights only speed up bus service when they are behind schedule (according to an Urban Liberty article). This adds predictability to my commute but does not help reduce the current wide gap that exists between car and bus commutes in the city.

This large time gap pushes more cars on the road which leads to more congestion and fewer people getting where they need to be at their desired time. At a micro level, here’s how this works. A current trip from Back Bay to the Longwood Medical Center area (LMA) that takes 14 minutes by car (using Waze) would take 35 to 40 minutes via Bus 39 (includes walking time). To travel 2.5 miles, I might as well walk. I don’t because I rarely have 40 minutes to allocate to a commute in the midst of work and school schedules. As a result, I drive. I would feel better about taking public transportation than driving, but the stress of being late is more painful than the positive feeling I get from taking the bus. A bus service that could get me to my appointment within say 20 – 25 minutes with a high degree of certainty would help me feel more confident about making my appointment on time. Again, we’re talking less than 3 miles of traveling.

Using TSP to speed up bus commutes and improve service reliability across the city seems like a no brainer. On wide streets, cities should be looking to convert a parking lane or a travel lane into a bus and ambulance lane (see The Amateur Planner’s suggestion for Huntington ave). City and state officials are not quite as excited about these ideas it seems. As the Urban Liberty article describes, city officials continue to be concerned about the impact of prioritizing public transportation on car traffic. Yes, TSP but not if it slows down car traffic. This type of thinking will lead to more congestion down the road. I am far from an urban planner, but I would suspect that good urban transportation planning in a city with growing population density should aim to encourage public transportation and discourage personal car use.

Share your thoughts on TSP and other methods to improve mobility in cities in the comments section below.