Waymo is releasing a software update to help its robotaxis navigate disabled traffic signals during power outages, the company said Tuesday in a blog post explaining why its self-driving vehicles got stuck at intersections during a power outage in San Francisco last weekend.
Waymo said the self-driving system in its robotaxis treats dead traffic lights as four-way stops, just as humans should. This allowed the robotaxis to function normally despite the massive disruption.
Instead, many of the vehicles requested a “confirmation check” from Waymo’s fleet response team to make sure what they were doing was correct. All Waymo robotaxis have the ability to perform these confirmation checks. With such a widespread outage on Saturday, there was a “concentrated spike” in these confirmation requests, Waymo said, which helped create all the congestion captured on video.
Waymo said it built this confirmation request system “out of an abundance of caution during our early implementation,” but is now refining it to “match our current scale.”
“While this strategy was effective during smaller outages, we are now deploying fleet-wide updates that provide the (self-driving software) with a specific outage context, allowing it to navigate more decisively,” the company wrote.
The software update will add “even more context about regional outages” to the company’s self-driving software. Waymo also said it will enhance its emergency response protocols by “incorporating the lessons learned from this event.”
While much has been made of the instances where Waymo’s robotaxis crashed during the outage, the company said its vehicles “successfully traversed more than 7,000 dark signals on Saturday.”
“Navigating an event of this magnitude presented a unique challenge for autonomous technology,” the company wrote.
Saturday’s mess is the latest example of how Waymo continues to discover unforeseen problems with its software and its approach to designing a reliable fleet of self-driving vehicles. The company has already had to provide multiple software updates to make its robotaxis wait for stopped school buses, prompting a National Highway Traffic Safety Administration investigation and a recall.
