It turns out that even San Francisco mayor Daniel Lurie, who once declared that the city should be a testbed for emerging tech, has his limits. Especially when that emerging tech creates a massive hours-long traffic jam that leaves thousands at a standstill.

Mayor Lurie has asked state regulators to bolster rules for autonomous vehicles nearly two weeks after Waymo robotaxis became immobile in heavy July 4 traffic, ran out of power, and blocked key streets, further compounding the gridlock. The traffic jam, which trapped municipal shuttles, became a citywide problem that affected thousands of people.

In his letter to the state Department of Transportation, which was viewed by TechCrunch, Lurie pointed to two events — a widespread power outage in December and the Golden Gate Bridge fireworks show on July 4 that attracted 100,000 spectators — both of which led to dozens of stranded Waymo vehicles and paralyzed traffic. The San Francisco Chronicle first reported on the letter.

The events, he said in the letter, “demonstrated that California’s current regulatory framework does not adequately address how autonomous vehicles operate during major incidents, planned or not. California’s challenge now is not just whether autonomous vehicles can operate safely under normal conditions, but also whether they can perform reliably during extraordinary ones.”

Lurie said autonomous vehicle manufacturers should be able to demonstrate four “core operational capabilities” and asked the California Department of Transportation to establish statewide standards to prevent future problems like the July 4 gridlock incident.

Under Lurie’s vision, companies would be required to immediately remove or relocate robotaxis from active travel lanes to keep people moving and be required to be able to adapt in real time, adjusting their routes, service area, and pickup and drop-off locations. Companies would also have to share real-time operations data with local agencies, including service disruptions, the locations of immobile robotaxis, and recovery efforts as well as demonstrate through testing that they can handle large influxes of people and traffic.

TechCrunch has reached out to Waymo for comment. The article will be updated once the company responds.

Any company that wants to operate a robotaxi service in California has to successfully navigate two testing and deployment permit processes, one administered by the state’s Department of Motor Vehicles and the other by the Public Utilities Commission. California’s existing regulatory framework is stricter than that of other states like Texas and Arizona, but that hasn’t dissuaded companies from trying to operate there.

San Francisco and the wider area that stretches south into Silicon Valley have long been a testbed for autonomous vehicle technology. Six companies, including Nuro, Waymo, and Zoox, hold driverless testing permits, which allow the vehicles to drive without a human safety operator behind the wheel.

But the area has also become the launch point for commercial services, which requires other permits from the DMV and CPUC.

Waymo is the largest, with an estimated 1,000 robotaxis operating in the Bay Area today. But there are plenty of others either testing or poised to launch commercial operations, including Amazon-owned Zoox as well as a premium robotaxi service that will be operated by Uber. Tesla has a branded robotaxi service but it doesn’t use driverless vehicles, nor does it have the permits to do so. Instead, Tesla has a charter transportation permit, which allows its own drivers to pick up and drop off riders throughout San Francisco in vehicles equipped with its advanced driver-assistance system rather than fully autonomous software.

Waymo’s scale has made it the focal point for regulators in San Francisco and beyond. The company now operates in 11 cities and has said it completes more than 500,000 paid rides every week. In San Francisco, Lurie noted that Waymo had agreed to restrict its service on July 4 near the waterfront and had even assigned a representative to the city’s emergency center. But that wasn’t enough to keep the Waymos out of the heavy traffic that occurred outside of that district.

Lurie said these voluntary actions are no longer enough — a reflection of just how big Waymo’s fleet has become. He said the four proposed requirements “will not undermine autonomous vehicles; they will strengthen them.”