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After running for nearly 90 years, overhead-electric buses in Cambridge will take their last trips this weekend

The temporary switch away from an electric vehicle has frustrated environmentalists. The MBTA says it's a necessary step.Barry Chin/Globe Staff

The MBTA’s electric trolley-buses, which have glided down the streets of Cambridge and surrounding towns for nearly 90 years, will be permanently disconnected from their overhead wires this weekend and replaced with buses that belch diesel fumes.

The buses, which ply routes between Harvard Square and Watertown and Waverley squares, will be sent to the scrapyard. Taking their place, for about two years, will be diesel hybrid models — which, in turn, will be replaced by battery-powered buses, T officials say.

The decision has frustrated climate and transit advocates, but won the support of some local elected officials. They say the T’s plan to build-out a garage for battery electric buses so they can replace the diesel hybrid ones by 2024 is sensible, and two years of diesel buses replacing electric ones is a small price to pay for progress toward electrifying the MBTA’s whole fleet.


“Sometimes you have to go a little out of the way to get to where you want to go,” said state Senator William N. Brownsberger, a Belmont Democrat who also represents Watertown and part of Boston.

The decision comes as the Massachusetts Bay Transportation Authority embarks on a years-long process to switch all of its buses to battery electric ones by 2040 and rebuild bus garages to accommodate charging. The T’s North Cambridge garage, home to the soon-to-be-scrapped trackless trolley-buses, will be renovated over the next two years to serve 35 battery electric buses.

Deelectrifying or removing the overhead wires will allow for Cambridge and Watertown to accomplish five long-awaited roadway construction projects by 2027, the MBTA said.

Still, switching from electric transit to diesel, at a time the state is trying to slash carbon emissions, is raising some eyebrows. Most of the MBTA’s fleet runs on fossil fuels.

“It’s not the outcome we would have liked to see,” said Jarred Johnson, executive director of the advocacy group Transit Matters. “We’re going to hold them accountable on this and make sure they bring that electrified service.”


The overhead wires used by the trolleys do come with unique challenges, said Scott Hamwey, the MBTA’s director of bus modernization. Barry Chin/Globe Staff

Some riders would prefer to keep the trolley-buses in service and even expand the overhead wire system to other parts of Greater Boston.

“With transit obviously being one of the most sustainable ways of moving large amounts of people and the goal to go green, this feels like a step in the wrong direction,” said Cambridge resident Omriqui Thomas, 13, a transit enthusiast who attended a public hearing on the issue.

Trackless trolley-buses have been moving people around the Boston area since the 1930s. Attached to electric overhead wires, the buses operate without tailpipe emissions. Over the decades, the MBTA replaced most of its trolley-bus routes with diesel buses, but kept the trolleys on routes 71 and 73, initially because of concerns about diesel fumes in the Harvard Station bus tunnel, and later because of concerns about climate change, said Bradley Clarke, president of the Boston Street Railway Association.

But the overhead wires come with unique challenges, said Scott Hamwey, the MBTA’s director of bus modernization.

“There are some major downsides to providing electric bus service the way we do out there today,” he said at a public meeting last month.

When a tree falls on a wire or ice builds up, or during construction, the MBTA replaces the trolley-buses with diesel buses. Those disruptions happen about 15 percent of the time, Hamwey said. The trolley-buses can’t be moved around to other parts of the system if they’re needed elsewhere, limiting flexibility.


Battery electric buses can move around more easily and offer far cleaner emissions than their diesel-guzzling counterparts. But they come with their own challenges, too. At a meeting last month, the MBTA said the five battery electric buses it owns have experienced significant range reductions on cold days. To fix that problem when the buses debut at the North Cambridge garage in 2024, the agency will equip them with diesel heaters — which will come with diesel emissions.

Bill Wolfgang, MBTA’s senior director of vehicle engineering, said at last month’s public meeting that the agency will monitor how often the diesel heaters are used and will stop using them when batteries improve in cold weather.

Environmental advocates are urging the MBTA to consider in-route chargers that would allow battery electric buses to get a boost at bus stops, instead of relying on diesel heaters.

“When we’re talking about the transportation sector in general, any emissions that we have are more than what we need, especially when there are solutions available out there to reduce them,” said Veena Dharmaraj, director of transportation at the Massachusetts Sierra Club.

Cambridge City Councilor Burhan Azeem said he is opposed to the change and called the removal of an electric system “a step backward.” But, he said, getting rid of the electrical wire system will make it easier for Cambridge to redesign streets to add bus and bike lanes.


“While I’m disappointed, the MBTA has the autonomy in this area and I can respect that,” he said. “We said our piece.”

Clarke, president of the Boston Street Railway Association, plans to be on the last trackless trolley-bus ride early Sunday morning around 1:30.

“I love the dear old things, but this is a business decision,” he said. “I think the T is between a rock and a hard place here.”

Taylor Dolven can be reached at taylor.dolven@globe.com. Follow her on Twitter @taydolven.