California Probes Waymo Robotaxi Stalls After SF Power Outage

California regulators are examining incidents in which Waymo autonomous vehicles stalled across San Francisco during a widespread power outage that disrupted traffic and prompted the company to temporarily suspend its robotaxi service. The outage, caused by a fire at a Pacific Gas and Electric substation, cut electricity to about 130,000 customers—nearly one-third of the city—on Saturday afternoon and exposed operational challenges facing large-scale deployment of driverless vehicles in dense urban environments.

The California Public Utilities Commission confirmed it is reviewing the incidents involving Waymo, an Alphabet subsidiary, after multiple reports and videos showed the company’s vehicles stopped at or inside intersections while traffic signals were not functioning. “We are aware of the outage and are looking into specifics,” a CPUC spokesperson said in an email, without providing details on the scope of the review. The CPUC, together with the California Department of Motor Vehicles, regulates permits for testing and commercial deployment of autonomous vehicles in the state.

Waymo paused its San Francisco service Saturday evening and resumed operations Sunday afternoon. The company said the interruption followed a fire at a PG&E substation that caused “significant and extensive” damage to utility infrastructure. Power outages began around 1:09 p.m. Saturday, peaked about two hours later and continued into Sunday, when tens of thousands of customers remained without electricity in parts of the city, including the Presidio, the Richmond District and downtown areas.

Videos posted on social media showed Waymo vehicles stopped with hazard lights flashing as traffic lights went dark. Some vehicles halted before entering intersections, while others stopped in the middle, forcing human-driven cars to maneuver around them. San Francisco resident Tyler Cervini said five Waymo vehicles crowded an intersection near his apartment in the Mission District as he attempted to reach the airport. His ride-hailing driver “had to swerve through them to pick me up,” Cervini said, adding that the driver appeared frustrated by the situation.

Waymo said its vehicles are designed to treat nonfunctioning traffic signals as four-way stops, but acknowledged that the scale of the outage created unusual conditions. “While the Waymo Driver is designed to treat non-functional signals as four-way stops, the sheer scale of the outage led to instances where vehicles remained stationary longer than usual to confirm the state of the affected intersections,” spokesperson Suzanne Philion said. She said the company coordinated with city officials and that most active trips were completed before vehicles were returned to depots or pulled over safely.

Experts said the disruption raised questions about operational readiness rather than core software capability. Philip Koopman, professor emeritus at Carnegie Mellon University and a specialist in autonomous vehicle safety, said the situation appeared to reflect an “operational management failure” in handling a surge of vehicles requiring assistance at the same time. Autonomous systems are often programmed to stop when uncertain and request remote support, he said, but the volume of vehicles involved overwhelmed response capacity. “If you have thousands of robotaxis that stop, you have a problem,” Koopman said. 

Concerns about road-blocking incidents are not new in San Francisco. In the months leading up to Waymo’s approval for commercial service by the CPUC in August 2023, city transportation and fire officials documented dozens of cases in which autonomous vehicles stopped unexpectedly and impeded traffic. Emergency responders warned that stalled vehicles could delay police and fire crews during critical situations.