Waymo Explains Why Its Robotaxis Got Stuck During the SF Blackout

Waymo is rolling out a software update to help its robotaxis navigate disabled traffic lights during power outages more “decisively,” the company said Tuesday in a blog post explaining why several of its self-driving vehicles became stuck at intersections during a blackout in San Francisco over the weekend.

Waymo explained that its robotaxis treat non-functioning traffic signals as four-way stops, similar to how human drivers are expected to behave. In theory, this should have allowed the vehicles to continue operating normally despite the widespread power outage.

However, many of the robotaxis instead requested a “confirmation check” from Waymo’s fleet response team to ensure their actions were correct. All Waymo vehicles are equipped with this capability. Because the outage was widespread, there was a “concentrated spike” in confirmation requests on Saturday, contributing to the congestion widely shared in online videos.

Waymo said it originally built the confirmation system “out of an abundance of caution during our early deployment,” but is now refining it to better align with the company’s current scale of operations.

“While this strategy was effective during smaller outages, we are now implementing fleet-wide updates that provide the [self-driving software] with specific power outage context, allowing it to navigate more decisively,” the company wrote.

The upcoming software update will provide the system with additional context about regional power outages. Waymo also said it plans to improve its emergency response protocols by incorporating lessons learned from this incident.

Although attention has focused on the robotaxis that became stuck, Waymo noted that its vehicles successfully navigated more than 7,000 dark traffic signals on Saturday.

“Navigating an event of this magnitude presented a unique challenge for autonomous technology,” the company wrote.

The incident underscores the ongoing challenges Waymo faces in developing and operating a reliable autonomous-vehicle fleet. Earlier this year, the company released multiple software updates to address issues with stopping for school buses, prompting an investigation by the National Highway Traffic Safety Administration and ultimately leading to a recall.