Waymo is shipping a software update to help its robotaxis more decisively navigate disabled traffic lights during power outages, the company said Tuesday in blog post that explains why its self-driving vehicles got stuck at intersections during a blackout in San Francisco last weekend.
Waymo said its robotaxis self-driving system treats dead stoplights as four-way stops, just as humans are supposed to. This should have allowed robotaxis to function normally despite the massive shutdown.
Instead, many of the vehicles requested a “confirmation check” from Waymo’s fleet response team to make sure what they did was right. All Waymo robotaxis have the ability to do these confirmation checks. With such an extensive outage on Saturday, there was a “concentrated spike” in those confirmation requests, Waymo said, which helped create all the congestion captured in the video.
Waymo said it built this confirmation request system “with plenty of care during our early development,” but that it’s now refining it to “match our current scale.”
“While this strategy has been effective in smaller outages, we are now implementing fleet-wide updates that provide [self-driving software] with a specific blackout frame, allowing it to navigate more decisively,” the company wrote.
The software update will add “even more context around regional outages” to the company’s self-driving software. Waymo also said it will improve its emergency response protocols “incorporating lessons learned from this incident.”
While there has been a lot of focus on the cases where Waymo’s robotaxis got stuck during the power outage, the company shared that its vehicles “successfully crossed more than 7,000 dark signals on Saturday.”
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“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 uncover unforeseen issues with its software and its approach to designing a reliable fleet of self-driving vehicles. The company already had to ship multiple software updates to get its robotaxis to wait for stopped school buses, which led to an investigation by the National Highway Traffic Safety Administration and a recall.
