It’s been more than 24 hours since a Red Line train derailed just as the morning commute was beginning, and service on the line is still disrupted for many riders.
What’s taking so long?
The MBTA offered an explanation in a series of tweets Wednesday, saying that when the train derailed, it struck and damaged sheds — called “bungalows” — that contain equipment that runs the T’s signal system.
Signals are a critical part of T infrastructure, as anyone who has ever been delayed by “signal problems” knows. They’re a sprawling network of sensors and cables that determine when trains can proceed — and when they cannot. On the Red and Orange lines, the system works by blocking off portions of track, allowing only one train at a time on each portion. The system also detects any obstructions or other issues with the tracks.
The equipment damaged in Tuesday’s derailment specifically controls the systems at the point where the Red Line splits into the Ashmont and Braintree branches, T spokesman Joe Pesaturo told the Globe on Wednesday.
“Without the signal system, trains must be given permission from our Operations Control Center to move from one station to the next, one train at a time. This also means we need people along the tracks to physically set the routes to direct trains,” T officials wrote in a tweet.
The damage to the signal equipment is also the reason the countdown clocks have been turned off along the entire Red Line.
If that sounds like a lot of damage, it is. Photos released by MassDOT on Wednesday showed twisted metal and crushed equipment at the site of the derailment. The T said it will need to replace equipment in the bungalows, including signals and cables, and rebuild them. The track itself will also need to be repaired. Workers are currently assessing the full extent of the damage, Pesaturo said.
See the T’s full tweet thread:
So Red Line service has resumed after this yesterday's derailment, but we know you're wondering why we're still delayed and what’s to come. Here’s we what we have so far...— MBTA (@MBTA) June 12, 2019
During the derailment, the train struck multiple signal bungalows outside of JFK/UMass. These are the sheds that house the hardware that controls our signal system.— MBTA (@MBTA) June 12, 2019
This failure prevents clear communication to train tracking, GPS apps, and countdown clocks. To avoid inaccurate predictions, we've turned off the countdown clocks across the Red Line.— MBTA (@MBTA) June 12, 2019
Looking ahead, bungalows will need to be rebuilt, new signals & cables installed, tracks repaired. At this time, we can't say how long that will take.— MBTA (@MBTA) June 12, 2019
For now, trains will continue to travel at slower speeds. We ask customers to allow extra time & use all available services.
We know this is a big ask. We sincerely appreciate all our riders' understanding and patience while crews work around the clock to fix this. We promise to keep updating you as more info becomes available.— MBTA (@MBTA) June 12, 2019