Riders are advised to expect 5 to 15 minute delays between Pleasant Hill and Concord as trains run on a single track between both stations. There is no timeline on when repairs will be complete and full service will be restored.
On Tuesday at around 5:30 p.m., two cars went off the tracks due to a warped rail that likely buckled in the heat. There were 50 people on board. All were evacuated and are said to be doing okay.
BART Spokesman Chris Filippi said heat is the main factor in the incident. He said the rail neutral temperature of its rails is approximately 115 degrees, but on Tuesday evening the rail temperature shot up.
"Whenever the rail temperature exceeds that by 20 degrees or more there’s a possibility for misalignment," Filippi said. "In this case our preliminary review indicates the rail temperature exceeded 140 degrees."
It was 106 degrees outside at the time of the incident. BART is monitoring the forecast and said it would listen to train operators if the heat poses any potential issues in the future.
"We’re going to pay attention to what they tell us," Filippi said. "In some circumstances we do slow down trains. We have done that in the past. If we need to do it again, we will."
Filippi noted that the rails are pre-treated so they have flexibility in extreme temperatures. He said a partial derailment like this is rare.
Crews spent the overnight hours working to ensure there was service on Wednesday. Riders are told to expect delays and to factor additional time into their commute as trains continue to single-track through the area.