San Francisco power outage: Waymo's fleet upgrade assures smarter rides after blackout chaos

A massive PG&E power outage plunged nearly one-third of San Francisco into darkness on December 20, 2025, stranding Waymo's autonomous vehicles amid gridlock and sparking viral videos of hazard lights flashing in stalled traffic. Triggered by a substation fire, the blackout affected around 130,000 customers at its peak, knocking out traffic signals across major corridors and prompting officials to urge residents to stay home.

Waymo paused services, directing over 7,000 vehicles through dark intersections, treating them as four-way stops, but faced backlogs from safety confirmation requests, leading to a fleet-wide software update to boost decision-making in crises and improve management of outages.

Waymo’s statement as reported by Times of India:


“The scale of the outage and the sheer number of disabled traffic lights were the primary contributors to city-wide gridlock. As signals went dark across major corridors, the resulting congestion required law enforcement to manually manage intersections. The situation was severe enough that the San Francisco Department of Emergency Management advised residents to stay home, underscoring the extraordinary nature of the weekend’s disruptions.

Navigating an event of this magnitude presented a unique challenge for autonomous technology. While the Waymo Driver is designed to handle dark traffic signals as four-way stops, it may occasionally request a 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. This created a backlog that, in some cases, led to response delays contributing to congestion on already-overwhelmed streets.

We established these confirmation protocols out of an abundance of caution during our early deployment, and we are now refining them to match our current scale. While this strategy was effective during smaller outages, we are now implementing fleet-wide updates that provide the Driver with specific power outage context, allowing it to navigate more decisively.

As the outage persisted and City officials urged residents to stay off the streets to prioritize first responders, we temporarily paused our service in the area. We directed our fleet to pull over and park appropriately so we could return vehicles to our depots in waves. This ensured we did not further add to the congestion or obstruct emergency vehicles during the peak of the recovery effort.

The path forward

We’ve always focused on developing the Waymo Driver for the world as it is, including when infrastructure fails. We are analyzing the event, and are already integrating the lessons from this weekend’s PG&E outage. Here are some of the immediate steps we’re taking:

Integrating more information about outages: While our Driver already handles dark traffic signals as four-way stops, we are now rolling out fleet-wide updates that give our vehicles even more context about regional outages, allowing them to navigate these intersections more decisively.

Updating our emergency preparedness and response: We will improve our emergency response protocols, incorporating lessons from this event. In San Francisco, we’ll continue to coordinate with Mayor Lurie’s team to identify areas of greater collaboration in our existing emergency preparedness plans.

Expanding our first responder engagement: To date, we’ve trained more than 25,000 first responders in the U.S. and around the world on how to interact with Waymo. As we discover learnings from this and other widespread events, we’ll continue updating our first responder training.

Undaunted in our mission to make our streets safer

We live and work in San Francisco, and we are grateful to the city’s first responders for their tireless work, and to Mayor Lurie for his leadership.

Backed by 100M+ miles of fully autonomous driving experience and a record of improving road safety, we are undaunted by the opportunity to challenge the status quo of our roads, and we’re proud to continue serving San Franciscan residents and visitors.”