SAN FRANCISCO — Alphabet Inc.’s Waymo acknowledged that its driverless cars contributed to traffic congestion during San Francisco’s massive weekend power outage, saying the scale of the disruption overwhelmed parts of its system and prompted the company to make immediate software and emergency-response changes.
The outage, caused by a fire at a PG&E substation, knocked out electricity to nearly one-third of the city Saturday, disabling hundreds of traffic signals and triggering gridlock across major corridors. As police officers were deployed to manually control intersections, stalled Waymo robotaxis became one of the most visible signs of the citywide disruption, drawing scrutiny from residents and elected officials.
In a blog post published Tuesday, Waymo said the unprecedented number of dark traffic signals strained safeguards designed for smaller outages. Its vehicles are programmed to treat non-functioning signals as four-way stops but in some cases they request a remote “confirmation check to ensure it makes the safest choice.”
“While we successfully traversed more than 7,000 dark signals on Saturday, the outage created a concentrated spike in these requests,” it said, adding that delays in confirmations contributed to congestion on already overwhelmed streets.
As the blackout persisted and the San Francisco Department of Emergency Management urged residents to stay home, Waymo said it temporarily suspended service and directed vehicles to pull over and park so they could be returned to depots in stages.
“I made a call to the Waymo CEO and asked them to get the cars off the road immediately,” Lurie said at a Monday news conference. “They were very understanding. … but we need them to be more proactive.”
The incident has prompted renewed questions about how autonomous vehicles perform during large-scale emergencies. San Francisco supervisors have called for a hearing on Waymo’s response, and a California regulator said Monday it is reviewing incidents involving stalled robotaxis during the outage.
Waymo said it is already rolling out fleet-wide software updates that give vehicles more context about regional power failures, allowing them to navigate intersections “more decisively.”
The company said it would strengthen its automated software to better handle power outages and is updating emergency preparedness plans, expanding coordination with city officials and continuing first-responder training, noting that more than 25,000 responders worldwide have already been trained to interact with its vehicles.
“While the failure of the utility infrastructure was significant, we are committed to ensuring our technology adjusts to traffic flow during such events,” a Waymo spokesperson said. “We are focused on rapidly integrating the lessons learned from this event, and are committed to earning and maintaining the trust of the communities we serve every day.”
Waymo launched autonomous ride-hailing service in Austin in March. It said last week its vehicles had traveled more than 6.3 million miles in the city through September. It’s launching service in San Antonio and Dallas in 2026.
