Waymo is rolling out a software update designed to help its robotaxis navigate disabled traffic lights more decisively during power outages, the company announced in a blog post on Tuesday. The update comes after several of its self-driving vehicles became stuck at intersections during a widespread blackout in San Francisco last weekend, leading to visible congestion.
According to Waymo, its self-driving system is programmed to treat non-functioning traffic lights as four-way stops, mirroring how human drivers are expected to react. This protocol should have allowed the robotaxis to continue operating normally despite the massive power disruption.
However, many vehicles instead initiated a “confirmation check” with Waymo’s fleet response team to verify their intended actions. While all Waymo robotaxis are equipped with this ability, the extensive nature of Saturday’s outage resulted in a “concentrated spike” in these confirmation requests. This surge in requests contributed to the congestion captured in numerous videos.
Why the Confirmation System Caused Delays
Waymo explained that this confirmation request system was initially built “out of an abundance of caution during our early deployment.” The company is now refining this protocol to “match our current scale.”
“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 stated.
The upcoming software update will integrate “even more context about regional outages” into the self-driving software. Waymo also committed to improving its emergency response protocols by “incorporating lessons from this event.”
Successful Navigation Amidst Challenges
Despite the focus on the instances where Waymo’s robotaxis encountered difficulties, the company highlighted a significant success: its vehicles “successfully traversed more than 7,000 dark signals on Saturday” during the same outage.
Waymo acknowledged the unique challenges posed by the situation, stating, “Navigating an event of this magnitude presented a unique challenge for autonomous technology.”
This incident marks the latest example of Waymo continuing to uncover unforeseen issues in its software and its approach to developing a reliable fleet of self-driving vehicles. The company previously had to issue multiple software updates and a recall following a National Highway Traffic Safety Administration (NHTSA) investigation into how its robotaxis behaved around stopped school buses.
