Progress on the Green Line

I recently had the chance to sit down and catch up with MBTA managers working on Green Line improvements.

Improving the Green Line has been a key priority of mine for years and I am pleased by what I am hearing.

Over the past few years, the MBTA has succeeded in implementing train position tracking on almost 100% of their Green Line train sets. Knowing exactly where the trains are creates some important improvement opportunities.

GPS supports implementation of transit signal priority — giving trains the green light when they need it, very important on the above ground portions of the B, C and E lines. Working with the City of Boston, the T has gotten the kinks worked out of this complex process. As of very recently, TSP is working on four intersections on the B and E lines and the T hopes to roll it out for another approximately 30 intersections over the next couple of years. TSP results in an average of 10 to 20 seconds savings for each trip at each intersection. Signal phase optimization to avoid grid lock with left turning traffic will also reduce delays.

GPS also allows reduction of train bunching. Trains get bunched up when the lead train experiences a delay. Bunching cascades because the lead train ends up with more passengers and has to spend more dwell time for boarding at each stop. Conversely, the trailing trains have fewer passengers and soon, they catch up and are running close to the lead train. Dispatchers are starting to use tablet applications that allow them to see how close trains are getting to each other further down the route, so that they can move away from simply releasing trains on a fixed schedule towards releasing them so as to keep spacing even. Full roll-out will take another couple of years.

The completion of work at Government Center offers a new opportunity for controlling schedule gaps — opening of a loop track will allow the T to keep a train ready to “run as directed” when delays are creating a gap. Especially when used with the GPS train tracking, this and other existing loops offer another tool to minimize train gaps.

Stop consolidation in the over-served section in front of BU is underway and, as the City of Boston maps out further work up Commonwealth Avenue, the T is studying options for further stop consolidation. Each unnecessary stop that can be eliminated saves valuable seconds. Additionally, the new cashless, all-door boarding process that the T is working on will reduce station dwell times.

Cumulatively, these savings add up to significant service improvements — as if additional train sets were added to each route.

In the longer term, the T does hope to add physical train capacity by using longer cars. An new fleet is 10 or more years away, but the T has commissioned studies of future demand and of options for improving capacity.

The demand studies build on the Core Capacity study that we worked to get going over the past few years. The final report of the Core Capacity study basically indicates that congestion on the Green Line — and other highways and transit routes — is expected to grow considerably over the years to come.

The prospect of increased investment in Green Line capacity — additional trains and the signal and power improvements to support them — has been on the table for several years now. While I had hoped that movement on all these fronts might happen more rapidly, I’m please by the concrete progress that is being made and I am committed to staying the course over the long term.