CAMBRIDGE, Mass. — Service on the Massachusetts Bay Transportation Authority’s Green Line remains disrupted today (Oct. 2) following a Tuesday derailment of a Green Line train — an incident the National Transportation Safety Board is investigating.
The MBTA says in a post on social media site X that shuttle buses continue to replace service between North Station and Medford/Tufts. Riders to Union Square should use regular bus lines to connect to shuttles, or take the Orange Line.
Seven people were taken to hospitals after a Green Line train with about 50 people aboard derailed near the Lechmere station about 5 p.m. [see “Seven taken to hospital …,” Trains News Wire, Oct. 1, 2024]. An MBTA official said the lead and center trucks of the train derailed as the train crossed a switch; and that agency was focusing on human error as cause of the derailment.
The NTSB said Tuesday night in a post on X that it was sending a team to investigate the derailment. Some investigators were expected to arrive Tuesday night, with others arriving today.
This sounds like what we called a “picked switch”. That does happen and it causes major problems. When part of the train passes over a correctly lined switch, the vibrations and pounding trucks from the following cars may “pick” the points of the switch causing them to move out of the correct line of travel. This would then cause the next set of wheels to move onto the adjacent track. The pulling force of the train would start derailing the cars at that point..
If it’s a single point streetcar switch, yes. The point couls flip and the spring couls close it in the other direction. Rules required the operator to stop at a single point facing switch, then proceed at no more than two points of power until the rear truck was through.
A conventional turnout wouldn’t flip to the opposite direction rather than fail as a split switch, putting the car on the ties or street paving.
Given the size ofthe T’s LRV’s, I doubt if they have any single point switches.