Feds to Investigate MBTA Safety

The top of the pantograph was facing the wrong way which would only occur if the pantograph top (shoe) snagged on something above.

It is not clear from the video whether the piece of material above had first fallen down to where pantograph snagged it and was then bent out of shape, or whether the pantograph jumped the wire first and rose up too high and pulled down the piece of material from its normal position up above The latter is less likely but could be the result of loosening of the wire in hot weather.

FTA releases more directives:

https://universalhub.com/2022/feds-find ... new-trains

All of the FTA directives, and the 90-page Final Report, can be found on this U.S. DOT page,

https://www.transit.dot.gov/about/news/ ... al-special

Article about the report https://www.masslive.com/boston/2022/08 ... blems.html

"MBTA officials have six weeks to respond to the four safety directives, which include a series of corrective actions the agency must take at the risk of losing federal funding. They build upon four earlier directives issued in June that the MBTA has already started responding to, including by shutting down the entire Orange Line, a drastic step taken to conduct necessary repairs."

Anyone in MBTA management who has not been jumping up & down calling for change all along needs to be removed.

More trouble for the Green Line this afternoon at Park Street. Sounds like a wire came down.
https://twitter.com/ArthurMansavage/sta ... vaOJhwa3bQ

https://twitter.com/wwuthmann/status/15 ... vaOJhwa3bQ

Final report on the fatal Red Line door incident with issue date of 6/12/2023:

https://www.ntsb.gov/investigations/Acc ... IR2307.pdf

A door safety interlock circuit that can be defeated by a short to chassis ground (which is what it looks in the picture in the report) is an extremely poorly designed safety circuit, as chassis ground is everywhere in a metal railcar, and it's by far the most likely thing for any wiring to short to.

Normally, a safety interlock is designed so a "high" signal is the "everything ok" signal and the "low" state is the fault signal, so anything that de-energizes the circuit (short to ground, etc.) forces the interlock into the fault state, which the prevents movement and is therefore safe.

Excellent point. I thought virtually all railroad equipment was designed to fail-safe into its most restrictive mode. At least that's the way signals are designed.

Remember that the 1500/1600s were not designed with sensitive edges that popped doors back open. There's discussion on here from back when about the "THESE DOORS DO NOT RECYCLE" stickers later replaced with "THESE DOORS DO NOT REOPEN AUTOMATICALLY."

The sensitive edge in this case was an in-house retrofit and I feel it's relatively understandable if it had a design flaw.