December 23, 2025 Waymo temporarily suspended its self-driving taxi service in San Francisco over the weekend after a citywide power outage caused its vehicles to stall at intersections and block streets. The incident has renewed concerns about how autonomous vehicles handle large-scale infrastructure failures.
The outage, triggered by a fire at a Pacific Gas and Electric substation, knocked out power to about 130,000 homes and businesses on Saturday, nearly a third of the utility’s customers in the city. Traffic lights across wide areas of San Francisco went dark, creating conditions that exposed limits in Waymo’s operational response.
Videos posted on social media showed Waymo vehicles stalled at intersections with hazard lights flashing, some stopping abruptly before crossing and others halting in the middle of the road, forcing human drivers to maneuver around them. Waymo paused service Saturday evening and resumed operations Sunday afternoon.
Waymo said its vehicles are designed to treat non-functioning traffic signals as four-way stops. At the same time, it acknowledged the scale of the outage created unusual challenges. A spokesperson said the company coordinated closely with city officials and that most trips were completed before vehicles were returned to depots or safely pulled over.
Residents described chaotic scenes. Tyler Cervini, who lives in the Mission District, said he encountered five Waymo vehicles crowding a single intersection while trying to reach the airport after transit services shut down. His Uber driver had to weave through the stalled cars to pick him up. “He seemed extremely frustrated by what was going on,” Cervini said.
Safety experts said the incident appears less about faulty vehicle software and more about fleet management. Philip Koopman, a professor emeritus at Carnegie Mellon University who studies autonomous vehicle safety, said self-driving systems are typically programmed to stop when uncertain and request human assistance. According to him, Waymo should have suspended service as soon as the problems started.”
Koopman warned that similar failures during more severe emergencies could have serious consequences. “What if this had been an earthquake?” he wondered. “You would have thousands of robotaxis blocking the road.”
The disruption revives concerns raised by San Francisco officials before state regulators approved Waymo’s commercial robotaxi service in August 2023. City transportation and fire departments had previously reported incidents of autonomous vehicles stopping unexpectedly and blocking traffic, potentially delaying emergency responders.
Waymo, which began as a Google project in 2009, now operates robotaxis in several U.S. cities and says its fleet is on track to complete more than 14 million rides this year. The company is also currently laying the groundwork for expansion into Canada. But the San Francisco outage comes as California considers expanding approval for heavier autonomous vehicles and passenger shuttles, a move opposed by labor groups.
