SAN FRANCISCO – The night the lights went out in San Francisco not only created a historic blackout but left Waymo with a marketing black eye.

Alphabet’s self-driving vehicle subsidiary said it will update software on all of its cars after a power outage in the San Francisco Bay Area on Dec. 21 that snarled intersections with inert autonomous vehicles because of impaired traffic lights and municipal infrastructure.

The outage – or Night of the Living Waymo Dead, as some call it – made the roads more dangerous, which tested how well self-driving cars can deal with abrupt system failures. Waymo stated in response that company is also changing its emergency response procedures to make sure that people work together better and make better decisions should similar things happen in the future. (The San Francisco blackout appears to be the first major documented incident of autonomous vehicles malfunctioning during a widespread power outage.)

Waymo didn’t say exactly when the upgrades would happen, but the firm did say that they will happen in all of its cars. The event shows how hard it is for self-driving cars to get from controlled testing to driving in real cities.

Waymo is still a long-term investment in self-driving cars for Alphabet Inc. Investors will be keeping a careful eye on how business improves the technology and deals with problems in the real world as robotaxi services grow.

Waymo says it is rolling out updates to its U.S. fleet to counter future disruption caused by power outages like the one that hit San Francisco last week.

The robotaxi biz was a focal point of the power outages at Pacific Gas and Electric (PG&E), with videos circulating online of its self-driving cars plonked in the middle of the city’s busy roads, unresponsive due to traffic signal failures.

The company responded by saying its fleet is programmed to treat disabled signals as four-way stops, but “the scale of the outage and the sheer number of disabled traffic lights” led to cases where its cars remained stationary for longer than usual.

Videos showed Waymo cabs lined up in streets with their hazard lights blaring, as human-controlled cars carefully navigated around the congestion.

In announcing the fleet tweaks, the Alphabet-owned company said its cars successfully navigated more than 7,000 dark traffic signals on Saturday, December 20.

It said that, in cases where its cars have to decide how to proceed through a dark intersection, it may send an additional request back to Waymo HQ for confirmation that its decision is the correct one. The scale of the outage prompted a spike in these requests, which created a backlog that, in turn, led to delays.

The updates being rolled out now include those that Waymo said would improve its cars’ decisiveness when navigating dark intersections by sending additional context around regional outages.

“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,” it said.

“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.”

Waymo also said it would be improving its incident preparedness and response capabilities following the PG&E outage, working with San Francisco mayor Daniel Lurie’s office in doing so, and promised to expand its first-responder training program.

“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,” it said.

The outage at PG&E, caused by a fire at a substation, affected more than 100,000 customers, according to its own updates, and its services were only restored fully on Tuesday.

Outages persist across the city at the time of writing, according to the G&E outage center, but these are being attributed to heavy storms hitting northern and central California and the damage they are causing, not the substation issues that led to traffic chaos over the weekend.

Global internet service provider Hurricane Electric confirmed a power issue at its Fremont facility last night, although it noted that its network remained “mostly functioning without issue.” In its latest update at 2043 UTC last night, it said power had been “restored, and we are working to restore affected systems. Our email and phones now are back working.”

Waymo Faces Scrutiny

City officials are demanding answers. San Francisco Supervisors Bilal Mahmood and Alan Wong have called for a public hearing to examine Waymo’s emergency response protocols. Their primary concern: whether the stalled autonomous vehicles delayed fire department access to emergencies during the crisis.

The incident has sparked broader questions among experts about whether autonomous vehicle technology is adequately prepared for the types of large-scale disasters — earthquakes, wildfires, and infrastructure failures — that periodically strike the Bay Area.

Amid the disruption, Tesla Inc. CEO Elon Musk said on X, “Tesla Robotaxis were unaffected by the SF power outage.”

Tesla does not operate a driverless robotaxi service in San Francisco.