On BART’s most recent podcast—by the way, BART does a monthly podcast—the transit agency spells out something that all riders should know: Unless it’s an emergency, do not force open the doors of a BART train.
The average commuter can definitely accomplish this feat; the sliding doors of a BART car don’t provide much resistance. But on the agency’s podcast, Harold Engle, who oversees a Concord repair shop that fixes broken down BART cars, explains what can happen next:
Someone holding a door open [...] might misalign a seal, which all of a sudden then makes the “no doors closed” indication. The operator can’t move the train without having all the doors closed.
[...] Often the failure repairs itself in a sense when the operator cycles the doors. They open them up, the patron removes whatever the obstruction was and the door gets all closed.
[...] But if the door is not identified or the specific car is not identified then we have to check all the doors on every car. So if you’re talking about a 10 car consist that’s about eight door leaves per car, that’s 80 door leaves that we have to check.
This should go without saying, but thanks to the train’s basic safety routine features, BART won’t move if it still thinks a door is ajar.
Admittedly, it’s often impossible to get on or off a crowded BART trains before the doors automatically snap shut. And part of the problem is BART’s technology.
As the San Jose Mercury News warned in 2014:
BART train doors are not like elevator doors — they close regardless of whether there is an obstruction. [...] The length of time the doors remain open is programmed by computers to keep trains on schedule. A train operator can override the automatic closure if he or she sees someone rushing to the door or sees an obstruction.
If the doors on trains didn’t close on anything in their path with robotic single-mindedness, this kind of thing might not happen. Then again, that would lead to delays of a different stripe. As one user on the commuter forum BART Rage observed in 2008:
Doors are easily the most abused part of any transit vehicle. Short of fixing the riders, you're not going to have a perfect door solution. [...] Elevator-like doors encourage operators to simply close the doors on people, which encourages people to force the doors open, which encourages more damage.
Repeat that cycle until all train service becomes impossible in a great, tumultuous BARTocalypse of our own making.
So, until the transit gods grant us smart doors that already know exactly how long to stay open at each stop, problems will happen. But be that as it may, still don’t force the doors open. On Muni, it’s just annoying, but on BART it can ruin an entire commute.