Per
Reddit, the T has quietly put at least one of the new battery-electric buses into revenue service. The one in the post is one of the 4300-series buses ultimately destined for the new Quincy Garage, not one of the 4200-series with left-side doors for the Harvard tunnel. I imagine there will be much more fanfare when the renovated North Cambridge facility opens and the new buses take over base service on the 71 and 73.
While I still think shutting down the trolleybus network and ripping out much of the infrastructure was a huge mistake, I'm glad to see the T making good on its promise to replace them with electric vehicles (albeit with diesel heaters for very cold weather), even if it's
two years late. The left-hand door buses will also significantly speed up outbound trips on the 71/73 since they'll be able to go back to boarding in the lower busway and riders will no longer have to loop back through Harvard Square on the surface. (It would also be nice to get more buses with left-side doors for the 66 and 86 so those routes could also board in the lower busway.)