Alphabet’s self-driving car unit, Waymo, said it will update the software that operates its autonomous vehicles and improve its emergency response procedures after several of its robotaxis stalled in parts of San Francisco on Saturday. The stoppages followed a widespread power outage that disrupted traffic and affected roughly one-third of the city.
Service was paused Saturday evening after a fire at an electricity substation knocked out power for about 130,000 residents, forcing some businesses to close temporarily. Social media videos showed Waymo vehicles stopped at intersections with hazard lights on as traffic signals went dark.
Waymo explained that its self-driving cars are designed to handle non-functioning traffic lights at four-way stops, but they may occasionally request a confirmation check. “While we successfully traversed more than 7,000 dark signals on Saturday, the outage created a concentrated spike in these requests,” the company said. “This created a backlog that, in some cases, led to response delays contributing to congestion on already-overwhelmed streets.”
The company added that its confirmation protocols were originally developed during early deployment and are now being refined to suit its current fleet size. Waymo plans to implement updates that give vehicles “specific power outage context, allowing it to navigate more decisively.” The company also said it would enhance its emergency response protocols based on lessons learned from the event.
Waymo operates more than 2,500 vehicles across the Bay Area, Los Angeles, Metro Phoenix, Austin, and Atlanta. The company resumed ride-hailing service in the San Francisco Bay Area on Sunday.
The incident has drawn the attention of regulators. On Monday, the California Public Utilities Commission announced it was reviewing the stalled Waymo vehicles. The CPUC, along with the California Department of Motor Vehicles, oversees the testing and commercial deployment of autonomous vehicles in the state.
This is not the first time Waymo has faced scrutiny over its self-driving software. Earlier this month, the company issued a recall to update its software after Texas officials reported that Waymo cars illegally passed school buses at least 19 times since the start of the school year. The National Highway Traffic Safety Administration launched a probe into the issue in October.
Waymo said the San Francisco outage provided important insights into how its fleet handles unusual circumstances and that the upcoming software updates and protocol improvements aim to prevent similar disruptions in the future.
