On Saturday 20 December 2025, a major blackout plunged San Francisco into darkness, the fault of a fire that broke out in a Pacific Gas and Electric (PG&E) electrical substation. The incident left around 130,000 homes and businesses without power, bringing parts of the city to a standstill, including autonomous cars.
Autonomous taxis have turned into immobile obstacles. At intersections with no traffic lights, these normally fluid vehicles came to a screeching halt with their blinkers on, forcing other motorists to manoeuvre around them as best they could. This rare and comical situation highlights the city’s dependence on ageing infrastructure, even as it adopts cutting-edge technologies.
According to a PG&E press release, the fire damaged essential substation equipment, causing massive power outages in the city centre, South of Market and surrounding areas. To isolate the incident and begin repairs, emergency crews were dispatched to the site and worked throughout the night, in coordination with the municipal emergency services. The authorities have confirmed that there were no casualties and that the cause of the incident is still under investigation.
Intersections without traffic lights, traffic rapidly coming to a standstill
The breakdown had an immediate and visible impact on the streets of San Francisco. More than a dozen intersections were left without traffic lights and quickly became gridlocked, making traffic dangerous for motorists and pedestrians alike. To deal with this unusual situation, the police were mobilised to regulate traffic in the most critical areas, and residents were asked to avoid all non-essential travel until the network was fully restored. The fire that broke out in a PG&E electricity substation also had an impact on the entire public transport network, which suffered significant delays.
Waymo forced to temporarily suspend its robot taxis
As briefly mentioned above, one of the most striking effects of the blackout was the immobilisation of Waymo’s autonomous vehicles. Waymo is an American brand that has been operating in San Francisco since August 2021 with the launch of its robotaxi service for « trusted testers ». Since June 2024, the autonomous robotaxi service has been available to everyone in San Francisco.
As a result of the power cut, many autonomous and therefore driverless taxis became stuck at intersections due to a lack of traffic lights, leading the company to temporarily suspend its operations in San Francisco as a safety precaution. This interruption exacerbated the traffic disruption in the city.
The dependence of autonomous vehicles on urban infrastructure
The local authorities stressed that this incident highlighted the fragility of certain infrastructures in a city that claims to be a world showcase for technological innovation. For the time being, the majority of users had their electricity back after several hours, although thousands of customers remained without power until the following day. Many shops were forced to close early, restaurants struggled to save perishable foodstuffs, and residents dependent on medical equipment required assistance from the emergency services.
When power was restored, attention turned to issues of preparedness and coordination between energy operators, municipal services and technology companies. Officials announced an audit to assess response protocols and consider measures to reduce the risk of similar outages in the future. For many residents, the blackout was a reminder that at the heart of even the most advanced cities, a reliable power supply remains the foundation of public safety, transport and daily life.
