Waymo to Update Robotaxi Software After SF Blackout Exposes Navigation Gaps

A massive power outage in San Francisco on Saturday exposed how autonomous vehicles cope when city infrastructure fails. A fire at a Pacific Gas and Electric (PG&E) substation knocked out electricity to nearly one-third of the city, disabling hundreds of traffic signals and triggering widespread gridlock.

Waymo, Alphabet’s self-driving unit, said the scale of the disruption overwhelmed parts of its system, forcing the company to pause its robotaxi service and pull vehicles off the road.

“The scale of the outage and the sheer number of disabled traffic lights were the primary contributors to city-wide gridlock,” Waymo said in its Dec. 23 blog post.

Waymo vehicles are programmed to treat dark traffic signals as four-way stops. But during Saturday’s (Dec. 20) outage, the number of intersections without power surged far beyond what the system typically handles.

“While we successfully traversed more than 7,000 dark signals on Saturday, the outage created a concentrated spike in these requests,” Waymo said. “This created a backlog that, in some cases, led to response delays contributing to congestion on already-overwhelmed streets.”

Videos shared on social media showed clusters of Waymo cars stopped at intersections with traffic lights out, becoming a visible symbol of the citywide disruption. As conditions worsened, the San Francisco Department of Emergency Management advised residents to stay home, while police and fire crews were deployed to manually control key intersections.

Waymo pauses service to ease congestion

With streets already overwhelmed and emergency responders trying to move freely, Waymo temporarily suspended operations.

“We directed our fleet to pull over and park appropriately so we could return vehicles to our depots in waves,” Waymo wrote. “This ensured we did not further add to the congestion or obstruct emergency vehicles during the peak of the recovery effort.”

Mayor Daniel Lurie later confirmed that city officials were in direct contact with the company during the outage. At a Monday news conference, Lurie said, “I made a call to the Waymo CEO and asked them to get the cars off the road immediately. They were very understanding. … but we need them to be more proactive,” according to the San Francisco Chronicle.

Software updates and emergency changes

In response, Waymo notes that it’s already making changes based on what it learned during the outage.

The company says it is rolling out software updates that provide vehicles with more information about regional power failures, allowing them to navigate intersections more decisively when signals go dark. Waymo is also revising its emergency response plans and coordinating more closely with San Francisco officials.

“We’ve always focused on developing the Waymo Driver for the world as it is, including when infrastructure fails,” the company said.

Waymo also stated that it will continue expanding training for first responders. According to the company, more than 25,000 emergency workers worldwide have already been trained on how to interact with its vehicles.

The incident has drawn scrutiny from regulators. The California Public Utilities Commission confirmed it is reviewing the stalling incidents, according to Reuters. This comes just weeks after Waymo issued a separate software recall related to how its vehicles interact with school buses in Texas.

Ride-hailing giants Uber and Lyft have confirmed plans to test robotaxis in the UK capital, teaming up with China’s tech firm Baidu as early as next year, pending regulatory approval.