Waymo Robotaxis Stall in San Francisco During Massive Citywide Power Outage
San Francisco faced a major disruption last weekend when autonomous taxi service operated
by Waymo stalled across the city during a widespread power outage.
On Saturday, December 20, a fire at a Pacific Gas & Electric substation knocked out power to around 130,000 homes and businesses, roughly one-third of the city. The outage cut electricity to hundreds of traffic signals, leaving major intersections in the dark.
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As traffic lights failed, dozens of Waymo robotaxis — part of the company’s fully driverless ride-hailing fleet — came to abrupt stops. Many vehicles lined up in intersections or halted mid-street with hazard lights blinking, blocking traffic and forcing human drivers to navigate around them. Videos shared on social media showed clusters of Waymo cars stuck in key junctions, adding to gridlock across downtown and residential neighborhoods.
Why the Cars Stopped
Waymo says its autonomous system treats non-functioning traffic lights as four-way stops. In typical outages, this strategy works. But the unprecedented scale of signal failures overwhelmed parts of its decision-making system.
The vehicles are programmed to sometimes request remote “confirmation checks” when encountering dark signals. On Saturday, the outage created a surge of these requests. Waymo handled over 7,000 dark intersections, but the volume caused delays in processing responses. That slowdown made cars more cautious and, in some cases, hesitant to proceed, contributing to widespread traffic jams.
City officials, including Mayor Daniel Lurie, asked Waymo to pause robotaxi operations so emergency crews could navigate the streets more easily. Waymo complied, safely returning vehicles to depots or pulling them over before halting service. The company resumed normal operations the next day after power and traffic control improved.
Waymo said it will roll out fleet-wide software updates to improve how its vehicles handle large-scale infrastructure failures like blackouts. The updates aim to give cars better “context” during outages, so they can make more decisive navigation choices without congesting intersections. Waymo also plans to enhance emergency response protocols and boost coordination with city authorities and first responders.
The outage reignited debate over autonomous vehicles operating at scale. Some transportation experts called the event an “operational management failure”, arguing Waymo should have suspended service earlier once signs of trouble emerged. They warn that in major disasters — earthquakes, storms, or wide utility failures — robotaxis could pose safety risks if not prepared for extreme conditions.
Local leaders have also voiced concern. City supervisors are pushing for hearings on how autonomous systems respond in emergencies, and regulators from the California Public Utilities Commission and Department of Motor Vehicles are reviewing the incident.
Waymo has expanded rapidly in recent years. The company now operates over 2,500 robotaxis across cities, including San Francisco, Phoenix, Austin, and Atlanta. The San Francisco service, open to the public since 2024, has been one of its busiest — and most scrutinized — due to frequent interactions with dense traffic and complex urban conditions.
This outage highlights a deeper challenge for autonomous vehicles: handling edge cases that humans navigate with experience and instinct. As companies scale up robotaxi deployments, regulators, city planners, and tech firms will need clearer standards for safety and emergency readiness on real roads. For more industry updates, visit our automotive news section.