• 1/17/2022 Park St Green Line Derailment

  • Discussion relating to commuter rail, light rail, and subway operations of the MBTA.
Discussion relating to commuter rail, light rail, and subway operations of the MBTA.

Moderators: CRail, sery2831

  by Head-end View
The news article said the train didn't derail but it sure looks derailed to me in the news photo.
  by west point
If you split a switch and go 3 feet or more one or more wheels are going to be on the ground. = derailed.
  by bostontrainguy
This does not make any sense to me. If that train was looping Park Street as shown it would be passing through a trailing point switch which is the track from Government Center. It would not be possible to pick a trailing point switch. Just guessing but perhaps a wheel in the articulation section somehow got caught in the frog? Hard to tell from the picture but no actual derailment.
  by Disney Guy
Could the train have been backing up? Being a Riverside train would have come from Government Center, then changing ends in the Park St. outbound platform and going around to the inbound platform. The purpose I don't know.

In the picture it looks like a car had jackknifed with the rear truck (forward truck for the direction of movement) going around clockwise to the inbound side and the center truck going straight to Government Center and the center articulation broken apart.
Last edited by Disney Guy on Thu Jan 20, 2022 9:50 pm, edited 1 time in total.
  by bostontrainguy
No, they would never be reversing there.
  by Disney Guy
Wait a minute. The news article said there were passengers aboard. So the train would not be looping and in the picture we are looking towards Govt. Ctr. The train would be coming into Park St. normally and turning right over a facing switch, headed for the wall track. But the center truck went straight, towards us and for the center (fence) track.

On second thought, had it been a looping train that got stuck, it looked like there was enough room for through trains in both directions to go around it avoiding the need to halt service.
  by dieciduej
To me the picture looks like a Riverside (D), Type 7, taking the wall rail (used for C and E routes) and the loop is the track on the right side of the picture. That would explain passengers being on the train. I've never scene a reverse move on the loop. Since the speed through there is 6 MPH or less and if the operator is on the ball or maybe off the ball caught it before it popped off the track.
  by bostontrainguy
Someone responded to the news report photo: "There was a train being turned in the loop at Park St. that was stuck behind the train that split the switch." That makes sense in that the train shown is going to Riverside and would not have passengers onboard. The train in front could have had passengers on board and would have been evacuated. But nothing else makes sense. The only switch that could have been picked was the trailing point switch that is under the shown Riverside train and that is not possible. And how did that train make it so far ahead if it was "derailed" at this switch? And what does "stopped short of a switch" mean when there are no switches between this switch and Boylston Street? All very weird.
  by Disney Guy
Going by "the stuck train pictured has come south from Govt. Ctr. and headed for the wall track outbound, moving to the left in the picture."

A train looping would not be stuck behind the former train but looks to have plenty of room to overtake, entering the picture from the right and coming around to where the photographer is standing.

Also looks like it was not necessary to terminate service back at Arlington; trains could all loop at Park St. at the location pictured. And other trains (were there any orphaned there?) doing a shuttle between North Station and Govt. Ctr. using Brattle Loop.

Or are clearances tighter than I described and the picture suggests?
  by GaryGP40
It's possible that one train was looping at Park and something happened, as it's pretty tight turn and would certainly probably not allow a car from Gov't Center to pass by along the wall track. It's hard to tell exactly what happened, but if the TP switch snapped back before the train was clear, perhaps the operator saw something and stopped the train before it was truly "derailed" but off enough to mess up the passage of trains from NS to Arlington.

It sounds to me like a defect in the switch, either mechanical or electrical. Knowing the media, the reports will say "the Green Line train that derailed tested positive..." :-D

Be interesting to keep an eye out and see what comes of the investigation. I can't imagine there's any way a train operating the loop at Park would be speeding.
  by MBTA3247
A train *might* be able to pass on the loop without issue, but the clearances are tight enough that you wouldn't be able to have any workers there, so it could be that the service suspension was for worker safety more than anything else.
  by GaryGP40
That's certainly another aspect of this situation as well. Also, if they needed to get mechanical equipment there to work on the car, that would definitely cause congestion and affect the safety of the workers too.
  by CRail
The train was going from Government Center to the wall track. The train stuck in the Park St. loop was more than likely stuck at a signal which would not clear because the junction was out of correspondence rather than being stuck behind fouling equipment.
  by Disney Guy
Just this week (or last week) cell phone systems were given the use of frequencies in the 5 gigahertz range amidst fears that there might be interference with aircraft, railroad, etc. communications. Critical communications might include wireless information sent from a train en route to wayside equipment to have switches set ahead of it.

More importantly a fix here would be improved methods to prevent throwing a switch while a train is passing over it. Excepting of course manual control of the switch by someone at the site to facilitate getting a stalled train off of the switch.

Depending, among other things, on how far its center truck wheels advanced, the disabled train (pictured) may have claimed the trailing point switch (where the photographer is standing). A starter would have to be on the ground there to flag any looping trains past a double red interlock signal (space permitting).