The T may be ready to get in synch with Beacon Street’s new traffic lights.
The Massachusetts Bay Transportation Authority plans to hire a consultant to analyze costs and benefits of giving Green Line trains priority at the computerized lights.
The use of trolley-recognition devices would allow traffic lights to extend the green, letting an approaching trolley pass through an intersection, or shorten the red, so a trolley does not have to wait as long at a red light.
Four MBTA officials met with Brookline officials on Dec. 21, nearly three weeks after the Globe ran a story about the new traffic light system on Beacon Street. The article reported that the Green Line was not integrated into the system, and that the T wanted the town to provide more information about how the system would benefit the trolleys.
“We spoke after the last story ran and decided that it was a good idea if the city and the authority got together and [discussed] what each side was working on,” said MBTA deputy chief of staff Kris Erickson.
As a result of that meeting, the MBTA is going to hire a consultant in a “couple of weeks or so, [February] at the latest,” he said, to perform the analysis.
HNTB Engineering, which the MBTA is looking to hire, this month submitted a preliminary proposal to complete the cost-benefit analysis for $61,000 in 22 weeks after being hired.
Even if the MBTA goes through with the cost-benefit analysis, however, trolleys might not get priority at Beacon Street intersections.
“The time savings might not be worth the cost to implement the system,” said John C. Lewis, the MBTA’s director of systemwide maintenance and improvements. “If we’re going to save minutes then the cost may be worthwhile, but if you’re [talking] seconds or milliseconds, the cost may not be the best option.”
Lewis added that having trains run faster between St. Mary’s Street and Cleveland Circle might create a bottleneck at the Kenmore station, where three Green Line branches converge and share the same track.
And, he said, trolley prioritization can work only at some of the intersections. “Can’t do it at every traffic light because [then we will] have a potential of a massive traffic jam in Brookline if [we] always give the Green Line priority,” he said.
William MacLellan, a signal engineer with HNTB, said it isn’t a good idea to “constrain any vehicular traffic either.”
“You don’t want to be throwing red lights in front of a car approaching” an intersection, he said.
Twenty-one computerized traffic signals have been installed on Beacon Street, replacing 25- to 40-year-old mechanical lights. Five of the 21 signals are at intersections that had stop or yield signs before.
The new traffic signals on the corners of Charles Street and Pleasant Street will begin working this month, while the traffic signal on Hawes Street and Beacon is expected to go online by early or mid-February, according to Bill Smith, who manages the Beacon Street reconstruction project for the town.
Once the project is complete, the computerized lights will vary the length of the signals depending on pedestrian and vehicular demand on the street, with sensors that will provide information about how long the line of cars is at the intersections.
If trolley-recognition devices are installed on Beacon Street trolleys, the street will become the first in the Boston area to use the technology.
Commonwealth Avenue in Boston used to have devices that allowed traffic lights to detect trolleys about 15 years ago, but that system no longer works.
Erickson said trolley prioritization never worked on Commonwealth Avenue because the trolley sensors, which were buried underground, were ripped up each time the street was plowed. “It was a different kind of system,” he said.
He added that it is too early to say if trolley recognition on Beacon Street could serve as a model for aboveground trolleys elsewhere in the MBTA system.