Alphabet's (GOOGL.US) self-driving department Waymo is being investigated by the NHTSA for allegedly violating rules regarding stopping for school buses.

The Office of Defects Investigation (ODI) of the National Highway Traffic Safety Administration (NHTSA) has initiated a preliminary investigation into Alphabet's (GOOGL.US) Waymo self-driving taxi company, as these vehicles failed to maintain a stopped state when approaching a stationary school bus. The investigation was prompted by reports of a Waymo self-driving car initially stopping near a school bus at an intersection, but then maneuvering around the bus and continuing to drive forward when the bus signaled for the vehicle to stop, eventually making a left turn and passing the bus on the left side. The stop arm of the school bus was already deployed at the time. At the time of the incident, the self-driving vehicle was operating with Waymo's fifth-generation Automated Driving System (ADS) and was not equipped with a safety operator. As part of the investigation, the ODI will determine how the ADS was designed to comply with school bus safety regulations. The NHTSA's latest investigation into Waymo's self-driving vehicles concluded in July after lasting 14 months. During this period, the agency found "no systemic safety violations." The decision to close the investigation without further action was made because Waymo decided to issue two significant recalls for the vehicles to address software issues affecting obstacle detection and avoidance on the road.