Metro

The Green Line will be getting more green lights at intersections

Transit signal prioritization could speed up trips on street-running portions of the Green Line.
Keith Bedford/Globe Staff/File
Transit signal prioritization could speed up trips on street-running portions of the Green Line.

The Green Line will be catching more green lights: The MBTA plans to greatly expand the use of technology that helps buses and trolleys squeeze through busy intersections before the traffic signal turns red.

It’s called “transit signal prioritization,” and it allows buses and trolleys that run along streets to request a green light as they approach an intersection. The T’s vehicles won’t get a yes every time, but even a few extra green lights along their routes should speed up service on those mass transit lines.

Earlier this year, the Massachusetts Bay Transportation Authority worked with Boston and Brookline to outfit municipally owned traffic signals at five intersections along Beacon Street and Commonwealth and Huntington avenues, where the Green Line’s B, C, and E branches run, with the technology.

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Now the T will spend $1.1 million to bring the technology to another 89 traffic signals at key intersections along the B, C, and E Green Line routes and on Massachusetts Avenue in Cambridge, a stretch that serves more than a dozen bus lines. (The Green Line’s D branch does not cross traffic intersections.)

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Because only a few Green Line intersections have been tested, the MBTA cannot say definitively whether the system has made trips faster for passengers. But transit officials are pretty confident it has.

“We anticipate that the run time and on-time performance is improving,” said Jessica Casey, deputy chief operating officer at the T, who presented the plans to the board that oversees the MBTA on Monday.

During a recent nine-day observation period during the morning rush, officials found that trolleys on the B and E branches in Boston saw lights at those select intersections stay green an additional 14 seconds, on average, and average red-light times were reduced by eight seconds. Meanwhile, traffic surrounding the intersections didn’t get any worse as a result, Casey said.

The upcoming work could be a precursor to further deployment of the technology in Greater Boston. Casey said the transit authority will explore adding the system on bus routes with heavy ridership and in places where cities and towns are already planning roadwork, so that signal prioritization can be tied into that project.

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Monica Tibbits-Nutt, a member of the T’s board, suggested signal prioritization be use in municipalities that are willing to help improve bus service in another way: with dedicated bus lanes.

“I would hope that we are giving priority to those communities that are willing to work with us on the dedicated bus lanes,” Tibbits-Nutt said.

Traffic-signal prioritization “is going to go a long way, but I think to get the level of service we really want, we are really going to need those dedicated lanes.”

Also at the board meeting on Monday, officials announced that two of the three contractors bidding for the Green Line extension’s largest contract said they could do it for under the $1.3 billion price tag the MBTA had set as a maximum.

In Novermber, the T is scheduled to select the winning bidder to design and build the above-ground rail expansion to Somerville. The T declined to say which contractor can’t do the project for below the maximum price.

Adam Vaccaro can be reached at adam.vaccaro@globe.com. Follow him on Twitter @adamtvaccaro.