Updated:Waymo's driverless taxi service has now resumed operations in the San Francisco area. A Waymo spokesperson attributed the service disruption to a power outage, explaining that Waymo's autonomous driving system is designed to treat faulty traffic lights as four-way stop signs. The scale of the power outage was so large that vehicles spent longer than usual checking the conditions at affected intersections, causing traffic congestion. The spokesperson added that Waymo will work closely with the San Francisco city government to coordinate response measures.
Driverless taxis perform well under normal road conditions, but what happens in unexpected situations? Waymo recently experienced a "shocking lesson" in San Francisco. Due to a large-scale power outage that caused traffic lights to malfunction, many Waymo self-driving cars were unable to read the lights and simply "crashed" and stopped in the middle of intersections. The company immediately announced a suspension of ride-hailing services in the area.
The AI crashed because the traffic lights weren't on?
According to CNBCReportImages circulating on social media show that during the power outage, several Waymo Jaguar I-PACE self-driving cars were found stopped in the middle of an intersection in San Francisco with their double yellow warning lights flashing.
With the power outage rendering traffic lights inoperable, these supposedly intelligent self-driving cars seemed to instantly lose their ability to make judgments. Instead of proceeding through intersections in an orderly fashion, the lack of traffic lights forced Waymo vehicles to adopt the most conservative strategy – stopping in place for safety – which in turn created roadblocks and caused traffic congestion in the surrounding area.
6 Waymo's parked at a broken traffic light blocking the roads. Seems like they were not trained for a power outage pic.twitter.com/9fBkoxgKwe
— Walden (@walden_yan) December 21, 2025
bad day to be a Waymo in SF during a PG&E-induced power outage pic.twitter.com/3SwEP993zn
— Mishaal Abbasi (@WhereIsMishaal) December 21, 2025
A fire at a substation caused a disaster, prompting Waymo to suspend services.
Waymo spokesperson Suzanne Philion later confirmed, "Due to a widespread power outage in the San Francisco Bay Area, we have temporarily suspended ride-hailing services in the area." She stated that the team is working closely with city officials to restore service as soon as possible.
The chaos stemmed from a fire at a PG&E (Pacific Gas and Electric Company) substation, which caused power outages affecting approximately 13 homes in San Francisco and surrounding areas starting Saturday morning, including Richmond District and Golden Gate Park.
Elon Musk: Tesla is not afraid.
While Waymo has not provided detailed technical explanations, its website states that the Waymo Driver system "responds to signs and traffic signals (such as traffic light colors)." It is speculated that when the camera cannot see any of the red, yellow, or green lights, the system may be unable to determine right-of-way, leading to an inability to make a decision.
At this point, competitors naturally wouldn't let the opportunity pass. Tesla CEO Elon Musk immediately posted a sarcastic comment on "X": "Tesla Robotaxi was completely unaffected by the San Francisco blackout." (This implied that Tesla's vision-based solution relied primarily on road condition judgment rather than simply on traffic light rules, or it was simply a way of mocking the competitor).
Tesla Robotaxis were unaffected by the SF power outage https://t.co/uaYlhcSx25
- Elon Musk (@elonmusk) December 21, 2025
Analysis: AI lacks human "common sense" and "flexibility".
In my opinion, this incident precisely exposes the vulnerability of current Level 4 autonomous driving technology when faced with "non-standardized scenarios".
For human drivers, seeing a traffic light malfunction (completely dark) instinctively triggers the "all-way stop" rule, allowing them to proceed by observing other vehicles' movements or exchanging glances. However, for Waymo's self-driving system, which places a high emphasis on strict rule-based regulations, the sudden disappearance of the crucial "traffic light" parameter might be interpreted as an unknown risk, forcing the system to stop for safety reasons.
While parking in place is a "safe" decision to avoid car accidents, in busy cities, it becomes a roadblock, creating another kind of danger. This once again reminds the industry that on the road to Level 5 fully autonomous driving, how to give AI human "adaptability" or how to make the infrastructure itself have a stronger V2I (vehicle-to-everything) backup mechanism are still urgent problems to be solved.
