In an unexpected turn of events, seven Waymo autonomous robotaxis came to a standstill on the Potrero Avenue 101 on-ramp in San Francisco on Tuesday at 9:30 p.m., obstructing the flow of traffic, as confirmed by Waymo and a viral Reddit video. The incident occurred when the first robotaxi in their convoy encountered a road closure marked by traffic cones on the Potrero Avenue on-ramp. With no alternative route available, the self-driving vehicles were compelled to join the freeway, as per a Waymo spokesperson.

The company is currently testing its autonomous robotaxi service on freeways with a human driver in the front seat, as California regulators have only recently approved Waymo to operate its autonomous robotaxi service on San Francisco freeways without a human driver. In response to the incident, Waymo immediately dispatched its Roadside Assistance team to manually retrieve the vehicles, and the entire event lasted no more than thirty minutes.

This is not the first time Waymo vehicles have caused traffic disruption, but it marks the first documented occurrence on a freeway. Cruise, General Motors’ autonomous vehicle subsidiary, has faced criticism for multiple instances of its vehicles malfunctioning and obstructing traffic, impeding first responders and public transit. Human drivers also often cause traffic congestion, but city officials and first responders in San Francisco have expressed frustration with both not being able to access and relocate robotaxis when they impede traffic and not being able to issue traffic citations to the autonomous vehicles. In San Francisco, a driver must be present in the vehicle for a citation to be issued.

Waymo has been providing a commercial autonomous taxi service in San Francisco since last August, offering tens of thousands of rides per week. The company has been cautious in its expansion, focusing on a cautious expansion of rider-only freeway operations in Arizona before progressing to California. Despite these advancements, safety concerns surrounding driverless cars persist, with Waymo facing criticism for incidents such as a self-driving car striking and killing a small dog in San Francisco.