Self-driving taxis operated by Waymo, a subsidiary of Alphabet Inc., came to a standstill during a major power failure in San Francisco on December 20, blocking traffic and stranding passengers. The incident occurred after a fire at a PG&E Corp. substation caused a widespread blackout that, at its peak, affected roughly 130,000 customers and knocked out thousands of traffic signals across the city.
Videos posted on social media showed multiple Waymo vehicles immobilized at intersections with their hazard lights on, creating significant traffic backups. The company's automated driving system, the Waymo Driver, is programmed to treat dark traffic lights as four-way stops. While the fleet successfully navigated approximately 7,000 non-functioning signals during the outage, the sheer scale of the event created a "concentrated spike" in requests for human confirmation checks, which are built into the system for complex safety decisions. This surge overwhelmed the response system, slowing down assistance and leaving some vehicles stuck.
In response to the escalating situation and a request from city officials for drivers to stay off the roads, Waymo suspended its service in the affected Bay Area regions, which included at least seven cities. Passenger Michele Riva recounted being stranded just a minute from his destination at a dense, dark intersection, unable to get through to overwhelmed customer support before abandoning the vehicle to walk home.
Waymo announced on Tuesday, December 24, that it is now working on software updates to better handle similar large-scale infrastructure failures. The updates aim to provide vehicles with more contextual information about regional power outages, allowing them to "navigate these intersections more decisively." Furthermore, the company is collaborating with San Francisco Mayor Daniel Lurie's office to refine emergency response plans and update training for first responders on interacting with autonomous vehicles during crises.
