Lessons learned after Waymo paused autonomous vehicle San Francisco service during power outage

Waymo temporarily suspended its autonomous ride-hailing service in parts of San Francisco last weekend after a widespread power outage left large sections of the city without functioning traffic signals, contributing to severe congestion.

The disruption followed a major power outage at PG&E that cut electricity to nearly one-third of San Francisco, disabling traffic lights across key corridors and forcing police to manually control intersections. The San Francisco Department of Emergency Management advised residents to stay home as gridlock spread across the city.

Waymo said its autonomous system is designed to treat dark traffic signals as four-way stops, but the scale of the outage created operational strain. The company reported that its vehicles successfully traversed more than 7,000 darkened intersections on Saturday, though a concentrated surge in confirmation checks slowed vehicle decision-making and added to congestion on already overloaded roads.

During early-stage deployments, Waymo built in conservative confirmation protocols to prioritise safety. According to the company, those safeguards proved less effective under the volume and density of this outage, leading to delayed responses in some locations. Waymo said it is now adjusting these systems to better reflect the scale of its current operations.

Power failure disabling traffic signals exposed limits of current autonomous response protocols, prompting fleet-wide updates

As conditions worsened and city officials prioritised access for emergency services, Waymo temporarily halted operations. Vehicles were instructed to pull over and park safely before being returned to depots in controlled phases, a move the company said was intended to avoid further obstructing traffic or emergency responders.

In response to the incident, Waymo is rolling out fleet-wide updates to provide its autonomous system with broader context during regional power failures, allowing vehicles to navigate dark intersections more decisively. The company is also revising emergency preparedness procedures and strengthening coordination with city authorities, including the office of Mayor Lurie.

Waymo said it will also expand engagement with first responders, building on existing training programmes that have reached more than 25,000 emergency personnel globally. The company framed the outage as a stress test of autonomous technology operating during infrastructure failures rather than routine conditions.

San Francisco remains one of Waymo’s most mature autonomous markets, and the company said the incident would feed directly into system improvements. Backed by more than 100 million miles of fully autonomous driving, Waymo said it remains committed to operating in complex urban environments, including during large-scale disruptions.