There is a National Transportation Safety Board open Waymo’s robotics have been spotted multiple times in at least two states after illegally passing stopped school buses.

The NTSB is focusing specifically on the more than 20 incidents that occurred in Austin, Texas, it said in a post Friday on the X.

“Investigators will travel to Austin to gather information on several incidents where automated vehicles failed to stop to load or unload students,” the NTSB told TechCrunch in a statement. A preliminary report is expected within 30 days, and the safety board will issue a more detailed final report in 12 to 24 months.

This is the first time Waymo has been investigated by the NTSB, but it’s the second investigation Waymo has opened into school bus problems. National Highway Traffic Safety Administration (NHTSA) Office of Defect Investigation A similar investigation opened in October.

Waymo also issued A software recall in December to resolve the issue. But previous software updates weren’t enough to stamp it out, and the school district in Austin, Texas — where most of the incidents were caught on camera — asked the company to suspend operations during pickups and drop-offs.

The new investigation comes as Waymo is in the midst of a rapid expansion around the United States. Just this week, the company began offering a robotaxi service in Miami, adding to its operations in Atlanta, Austin, Los Angeles, Phoenix and the San Francisco Bay Area.

“We safely navigate thousands of school bus encounters weekly across the United States, and Waymo drivers continue to improve. There were no collisions at the events in question, and we are confident that our safety performance around school buses is superior to that of human drivers,” Waymo’s chief safety officer, Mauricio Peña, said in a statement to TechCrunch. “We see this as an opportunity to provide the NTSB with transparent insight into our safety-first approach.”

The NTSB differs from the NHTSA in that it is not a federal regulatory agency It cannot issue fines or penalties. Rather, safety boards typically conduct in-depth investigations to identify root causes of problems in the transportation world. When an investigation is complete, the board often holds hearings and issues non-binding recommendations.

The first notable incident in which a Waymo vehicle drove over a stopped school bus was last September in Atlanta, Georgia. The Waymo exited a driveway and crossed perpendicularly in front of the school bus from the right side of the bus. As the children got off the bus, the robotaxy turned left and headed down the street.

Waymo said at the time that the car was unable to see stop signs or flashing lights, and has since said it fixed this particular situation with a software update.

But as Waymo patched up the specific situation it faced in Atlanta, some of the company’s vehicles were caught passing stopped school buses in Austin, Texas. Local news outlet KXAN released videos from cameras mounted on school buses showing Waymo vehicles making illegal maneuvers. Multiple events.

“We continue to engage fruitfully with the Austin Independent School District and appreciate their reported success in reducing human-operated violations around school buses from 10,000+ annually,” Pena said.