San Francisco blackout leaves Waymos stalled at dark intersections

SAN FRANCISCO, December 2025 — A blackout left Waymo robotaxis stopped in traffic across the city on Saturday, Dec. 20. Here's what happened, what it cost, and what went wrong.

Cost and outcome (as of Dec. 24, 2025)

Outage: began around 1:09 p.m. Saturday and peaked about two hours later at about 130,000 PG&E customers. (CNBC) TechCrunch, citing SFGate, put it at about 120,000. (TechCrunch)
Cause: a substation fire with "significant and extensive" damage, PG&E said. (CNBC)
Service: paused Saturday evening and the first half of Sunday, resumed Sunday evening. (CNBC)
Dark signals crossed: "more than 7,000" on Saturday, per Waymo. (Waymo)
Number of stalled cars: not disclosed by Waymo.

What happened

Resident Matt Schoolfield told CNBC he saw at least three Waymos stopped in traffic on Saturday evening. "They were just stopping in the middle of the street," he said. Mayor Daniel Lurie said on X that police officers and fire crews were deployed across affected neighborhoods, CNBC reported.

Waymo spokesperson Suzanne Philion told CNBC the outage "was a widespread event that caused gridlock across San Francisco." She said that "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. This contributed to traffic friction during the height of the congestion." She added: "The majority of active trips were successfully completed before vehicles were safely returned to depots or pulled over."

As of Sunday afternoon, PG&E had restored power to all but 17,000 customers, the BBC reported.

Waymo's explanation

In a Dec. 23 blog post, Waymo said its cars "may occasionally request a confirmation check to ensure it makes the safest choice." The outage "created a concentrated spike in these requests," producing "a backlog that, in some cases, led to response delays contributing to congestion on already-overwhelmed streets."

Waymo said it built those protocols "out of an abundance of caution during our early deployment" and is refining them "to match our current scale." It listed three steps: fleet-wide updates giving cars "more context about regional outages," improved emergency response protocols, and more first-responder training. It said it has trained "more than 25,000 first responders."

Waymo said that as the outage dragged on and city officials urged residents to stay off the streets, it "temporarily paused" service. It "directed our fleet to pull over and park appropriately so we could return vehicles to our depots in waves," so as not to "obstruct emergency vehicles during the peak of the recovery effort."

The scale involved

Waymo described the outage as cutting power "to nearly one-third of San Francisco." It said the city's Department of Emergency Management advised residents to stay home. Waymo's fleet is large enough that a citywide pause matters: CNBC reported that the company had recently crossed an estimated 450,000 weekly paid rides, and the BBC reported that Waymo said it provided more than 14 million trips in 2025, across all its cities.

Bryan Reimer, a research scientist at MIT, told CNBC that power outages are entirely predictable and that AV developers should be held responsible for "chaos gridlock," as human drivers would be.

What went wrong

A safety check became a bottleneck. Waymo's own account says remote confirmation requests backed up.
The cars blocked traffic. Witnesses and Waymo both describe vehicles stationary in the street.
Service had to stop. Waymo paused rides until Sunday evening.
What we don't know yet: how many Waymos stalled, for how long, and whether any delayed emergency vehicles.

Our follow-up question for Waymo

How many vehicles stalled during the outage, and how many remote assistance staff were on duty?

Later developments (added Oct. 2026)

In March 2026, San Francisco supervisors held a hearing on the stalls (SFCTA). Waymo's Jan. 30, 2026 filing with the California Public Utilities Commission showed 1,593 stops of two minutes or more (CPUC). That is covered in Part 2.
On Dec. 27, 2025, Reuters reported that the California Public Utilities Commission and the Department of Motor Vehicles said they were looking into the incident. As of Oct. 25, 2026, we found no NHTSA investigation or DMV enforcement action specific to the blackout. (Reuters)

Sources

CNBC, “Waymo resumes robotaxi service in San Francisco after blackout chaos — Musk says Tesla car service unaffected,” Dec. 21, 2025. cnbc.com
TechCrunch, Anthony Ha, “Waymo resumes service in San Francisco after robotaxis stall during blackout,” Dec. 21, 2025. techcrunch.com
BBC News, “Waymo robotaxis stop in the streets during San Francisco power outage,” Dec. 22, 2025. bbc.com
Waymo, “Autonomously navigating the real world: lessons from the PG&E outage,” Dec. 23, 2025. waymo.com
CNBC, “Waymo will update driverless fleet after San Francisco blackout to improve navigation during outages,” Dec. 23, 2025. cnbc.com
TechCrunch, Sean O'Kane, “Waymo explains why its robotaxis got stuck during the SF blackout,” Dec. 24, 2025. techcrunch.com
The San Francisco Standard, Garrett Leahy, “Supervisors grill Waymo about 1,500 stalled cars during December blackout,” March 3, 2026. sfstandard.com
Reuters, “Waymo's San Francisco outage raises doubts over robotaxi readiness during crises,” Dec. 27, 2025. reuters.com
San Francisco County Transportation Authority, “San Francisco Board of Supervisors Hold Hearing on Waymo Operations During December 2025 Blackout,” March 2, 2026. sfcta.org
Waymo LLC, “Response of Waymo LLC on the January 12, 2026 Administrative Law Judge's E-Mail Ruling,” CPUC Rulemaking R.25-08-013, filed Jan. 30, 2026. docs.cpuc.ca.gov

Disclosure: [not in copy] Editor placeholder