Waymo is pushing a software update to help its robotaxis “more decisively” navigate disabled traffic lights during power outages, the company said Tuesday in a blog post explaining why its autonomous vehicles got stuck at intersections during a power outage in San Francisco last weekend.
Waymo said its robotaxis’ self-driving system treats brake lights like four-way stops, just like humans are supposed to do. This should have allowed the robotaxis to function normally despite the massive outage.
Instead, many vehicles requested a “confirmation check” from Waymo’s Fleet Response Team to ensure what they were doing was correct. All Waymo robo-taxis have the capability 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 filmed.
Waymo said it built this confirmation request system “out of an abundance of caution during our first deployment” but is currently refining it to “match our current scale.”
“While this strategy has been effective during minor outages, we are now implementing fleet-wide updates that provide the [self-driving software] with a specific power outage context, allowing it to navigate more decisively,” the company wrote.
The software update will add “even more context on regional outages” to the company’s self-driving software. Waymo also said it would improve its emergency response protocols by “incorporating lessons from this event.”
While the focus has been on instances where Waymo’s robotaxis got stuck during the power outage, the company said its vehicles “successfully passed through more than 7,000 dark signals on Saturday.”
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“Managing 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 autonomous vehicles. The company has already had to ship several software updates to make its robotaxis wait for stopped school buses, leading to an investigation by the National Highway Traffic Safety Administration and a recall.
