By Abhirup Roy and David Shepardson
Dec 22 (Reuters) - A top California regulator said it was looking into incidents in which robotaxis from Alphabet unit Waymo stalled in parts of San Francisco on Saturday due to a widespread power outage that snarled traffic and gridlocked parts of the city.
Waymo paused service Saturday evening following a fire at a PG&E substation that knocked out power to roughly one-third of the city, affecting about 130,000 residents and forcing some businesses to close temporarily.
Multiple videos posted on social media showed Waymo robotaxis stuck at intersections with hazard lights turned on as traffic lights stopped working due to the outage.
The incident highlighted concerns around the unforeseen situations that can arise for autonomous vehicle operators as they race to deploy driverless taxis across the U.S.
Waymo, which has a fleet of more than 2,500 vehicles operating in the Bay Area, Los Angeles, Metro Phoenix, Arizona, Austin, Texas and Atlanta, Georgia, said it resumed its ride-hailing service in the San Francisco Bay Area on Sunday, a day after temporarily suspending operations.
"We are aware of outage and are looking into specifics," a spokesperson for the California Public Utilities Commission said in an email to Reuters, referring to Waymo vehicles stalling. The regulator did not provide details of exactly what it was examining.
Waymo did not immediately respond to requests for comments on CPUC's statement.
Commercializing robotaxis has been harder than expected due to the high cost of investment, tough regulations and investigations following collisions that forced many companies to shut down. But self-driving cabs have returned to the limelight after Tesla launched a service in Austin, Texas, earlier this year and Waymo picked up the pace of its expansion.
The CPUC, along with California's Department of Motor Vehicles, regulates and issues permits for testing and commercial deployment of robotaxis.
While the Waymo Driver - the company's fully autonomous driving system - is designed to treat non-functional signals as four-way stops, the sheer scale of the outage led to instances where vehicles remained stationary longer than usual, Waymo said in a statement on Monday.
A spokesperson said the company was integrating lessons learned from the event and was committed to ensuring its technology better adapts to traffic conditions during similar disruptions.
(Reporting by Abhirup Roy in San Francisco, David Shepardson in Washington D.C. and Harshita Mary Varghese in Bengaluru; Editing by Tasim Zahid and Nia Williams)
