Problems began Friday morning, but trains have had to run at only one-third of their normal speed in manual mode.
Those hoping to start their weekend a little early had no such luck. Especially the people trying to leave San Francisco on a Pittsburg Bay Point or a Dublin Pleasanton train. Trouble on the tracks is forcing riders to play a game of musical chairs that adds 20 minutes onto a trip.
When the trains run automatically, they go about 80 miles per hour. But, when the system shuts down, the top speed of a train in manual mode is 27 miles per hour. That can create all sorts of problems.
The root of the problem is a broken component known as a 'mux box.' Mux is short for Multiplexer; it's what sends the signals from the train control system to the train itself.
A BART spokesperson told ABC7 News those mux boxes are 40 years old.
"The people that made these components do not make them anymore. And, so, we have to scour the internet to find replacements. We have to come up with ideas on our own, and refurbish them. And, that's what we've been doing," said BART spokesperson Alicia Trost.
"It's hard to figure out when you'll actually be where you need to be. Like. I have a job interview tomorrow morning and I'm nervous I won't get there in time," said on BART rider named Gina.
Some riders say the announcements over the loudspeaker have been confusing and the transit agency's information booth is understaffed. At worst case, those delays could continue throughout the Friday evening commute.
BART is looking for a new train control system but that will cost hundreds of millions of dollars.