Muni metro slowed to “walking speed” Thursday morning, slowing the commute of some 75,000 riders.
The metro system experienced issues with its automatic train control system, the computer network that runs the trains once they enter the subway, according to the San Francisco Municipal Transportation Agency.
Trains are piloted manually by operators when they run on city streets.
The agency ran ten shuttles on the surface to ferry riders for the K, L, M and N train routes, according to the agency. SFMTA also recommended train riders take its bus routes instead, on social media on Thursday.
Service resumed to normal just shy of 11 a.m., according to SFMTA, at the tail end of the morning commute for tens of thousands of riders.
“Is there a reason the trains are running at walking speed between Montgomery and Embarcadero?” wrote Twitter user @HealthEDena, in a question to the SFMTA Twitter account, Thursday morning at about 9 a.m.
They weren’t alone. Twitter user @chelsmark wrote, “Here’s some @SFMTA_Muni math for you: this morning I got on a train 20 minutes earlier than I normally do so I could arrive 30 minutes early to work, and instead I’m 10 minutes late.”
The automatic train control issues are increasingly cropping up because the system is aging, said SFMTA Director of Transit Julie Kirschbaum, in an SFMTA Board of Directors meeting last Tuesday.
“What we’ve been doing in the last number of years in terms of upgrading the train control system is kind of moving away from those underlying patches and older equipment,” she told the SFMTA board. “We’re just in the final stages actually right now in the next month or so to finally do the new cutover of the new system that will take a lot of that old patchwork and the risk associated with it out of the system.”
Even upgrading the system may see bumps in the road for train riders, however.
“It is the case, as with any software, there are issues and bugs,” she said. Though their testing is pretty “rigorous,” sometimes computer glitches may interrupt service.
“But,” Kirschbaum added, “we’ve been getting better at it.”