On December 21, 2025 (local time), Waymo's autonomous taxi service ground to a halt in San Francisco, California, USA. This suspension came in the wake of a city-wide power outage. The blackout was sparked by a fire at a San Francisco substation. As a result, traffic lights started malfunctioning, leaving numerous Waymo vehicles stuck at intersections and creating significant traffic jams.

In English, when describing a situation where a service stops, "suspend" is a bit more formal. "Ground to a halt" is a more vivid and commonly used expression in daily English to convey that something stops completely. Also, "spark" is a more natural verb than "trigger" when talking about the cause of an event like this. And "create traffic jams" is a more straightforward way to say it compared to "result in traffic congestion".

Following the incident, Waymo promptly declared the suspension of services throughout San Francisco. The company then worked hand - in - hand with municipal authorities to get operations back on track. On December 25, Waymo unveiled a sweeping upgrade for its fleet. It introduced three emergency optimization measures. These included software updates, enhanced emergency response protocols, and updated training materials for first responders. The aim was to bolster the vehicles' capacity to deal with infrastructure failures.

In English, "promptly" is a more natural adverb to show quick action compared to just "subsequently". "Work hand - in - hand" is a more vivid and commonly used phrase to describe close cooperation. "Unveiled" is a more formal and appropriate verb when introducing something new like an upgrade. "Bolster" is a more advanced and suitable verb than "enhance" in this context to show strengthening the ability.