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What happened when Waymo robotaxis met a San Francisco blackout

Andrew Nusca
By
Andrew Nusca
Editorial Director, Brainstorm and author of Fortune Tech
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December 22, 2025, 6:08 AM ET
A Waymo robotaxi unable to detect traffic lights after a major power outage in San Francisco, California on December 20, 2025. (Photo: Tayfun Coskun/Anadolu/Getty Images)
A Waymo robotaxi unable to detect traffic lights after a major power outage in San Francisco, California on December 20, 2025. Tayfun Coskun/Anadolu/Getty Images

Good morning.  Extremely lean and mean (well, merry, really) for the rest of this week as we head into our annual winter break.

We’ll hang things up for the year on Dec. 24 and pick things back up on Jan. 5. 

Happy holidays. (Yippee-Ki-Yay.) —AN

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What happened when Waymo robotaxis met a San Francisco blackout

A Waymo robotaxi unable to detect traffic lights after a major power outage in San Francisco, California on December 20, 2025. (Photo: Tayfun Coskun/Anadolu/Getty Images)
A Waymo robotaxi unable to detect traffic lights after a major power outage in San Francisco, California on December 20, 2025.
Tayfun Coskun/Anadolu/Getty Images

An extraordinary experiment happened over the weekend in San Francisco.

What would a fleet of autonomous vehicles do when a widespread power outage knocked out traffic lights across one-third of the city? 

We quickly found out—and the results were plastered all over social media. 

On Saturday afternoon, Waymo vehicles throughout SF opted to stop where they were or pull over and throw on their hazard lights—“blocking intersections” and “compounding gridlock,” observed the San Francisco Standard—leading the Alphabet-owned robotaxi operator to suspend service throughout the city. (It resumed Sunday evening.)

In a statement, Waymo said that its vehicles are “designed to treat non-functional signals as four-way stops” but “the sheer scale of the outage led to instances where vehicles remained stationary longer than usual.” 

As locals worked through the outage, a moderate debate about the robotaxi fleet continued online. Was it so wrong to expect Waymo’s vehicles to play it safe when infrastructure stopped working? After all, aren’t human drivers predictably chaotic when things go sideways? What exactly should robotaxis optimize for: traffic flow or citizen safety? 

And: Just how safe is stopping if you prompt traffic to go around you?

Waymo resumed service Sunday evening, no doubt grappling with these questions (and what city officials might have to say about them). “We are already learning and improving from this event,” it said. —AN

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—Shield AI: Sitting at a global inflection point for fully autonomous warfighting.

—SoftBank cashes out to back OpenAI. The Japanese conglomerate is looking under every rock to fulfill its “all in” OpenAI funding promise.

—Chaos at CISA. A failed, unsanctioned polygraph by its acting director has the U.S. cybersecurity agency in disarray.

—PE firms acquire Clearwater Analytics for $8.4 billion. Permira and Warburg Pincus lead the investor group seeking to buy the fintech firm.

—Uber goes to London. A robotaxi trial in partnership with Baidu will begin in the first half of next year.

—Data center deals reach $61 billion worldwide in 2025, according to S&P Global.

—Chatbots’ uncanny valley. Making AI agents more human-like creates cognitive dissonance and trust issues, researchers say.

—Daylight between David Sacks and tech lobbyists. Tech reps say the AI czar’s push to use Trump’s executive order to suppress state AI regulation is the right idea, wrong execution.

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About the Author
Andrew Nusca
By Andrew NuscaEditorial Director, Brainstorm and author of Fortune Tech
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Andrew Nusca is the editorial director of Brainstorm, Fortune's innovation-obsessed community and event series. He also authors Fortune Tech, Fortune’s flagship tech newsletter.

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