By David Shepardson
(Reuters) - Alphabet (NASDAQ:GOOGL)'s Waymo unit has recalled 444 self-driving vehicles after two minor collisions in quick succession in Arizona because a software error could result in them inaccurately predicting the movement of a towed vehicle.
All of the vehicles are in the company's possession and had software updates last month.
Waymo said in a filing Thursday with the National Highway Traffic Safety Administration (NHTSA) that in December one of its autonomous vehicles operating in Phoenix, Arizona made contact with a "pickup truck being towed backwards and at an angle relative to the towing vehicle."
The towing vehicle was "improperly traveling straight
in the middle shared turn lane and the pickup truck being towed was partially occupying the travel lane immediately to the right of the middle shared turn lane."
The Waymo AV was in the same travel lane as a
portion of the towed pickup truck when the front left of the Waymo AV made contact with the pickup truck, the company said.
Waymo said that several minutes later "a second Waymo AV made contact with the same off-angle towed pickup truck, which
had continued after the first contact and was still occupying multiple lanes."
The two events were both at low relative speeds. Neither collision resulted in injuries, Waymo said.
Waymo met with NHTSA on the issue on four separate occasions starting on Dec. 15 and most recently last week.
Waymo said it "carefully considered points raised by NHTSA in these discussions."
Waymo’s Safety Board said due to the unique characteristics of the collisions that it" warranted submitting this report to NHTSA to fulfill relevant notification obligations."
The recall announcement comes days after a crowd vandalized and set fire to a Waymo self-driving car using a firework in San Francisco, marking the most destructive attack so far on driverless vehicles in the United States.
California lawmakers and labor unions rallied on Monday to call for laws to not allow autonomous trucks without human drivers, amid rising safety concerns after accidents.
Separately, NHTSA said electric automaker Lucid Group (NASDAQ:LCID) recalled 189 of its Air vehicles to fix a software issue that could have resulted in loss of drive power.
Waymo and Lucid did not respond to Reuters requests for comment.