Core Points - The National Highway Traffic Safety Administration (NHTSA) has initiated a preliminary investigation into Waymo's autonomous taxis due to incidents where the vehicles failed to stop near stationary school buses [1] - The investigation was prompted by reports of a Waymo autonomous vehicle initially stopping at an intersection but then proceeding to maneuver around the school bus, which had its stop arm extended [1] - The autonomous vehicle was operating under Waymo's fifth-generation autonomous driving system (ADS) without a safety operator at the time of the incident [1] - NHTSA's previous investigation into Waymo's autonomous vehicles concluded in July, lasting 14 months, and found "no systemic safety violations," leading to the decision to take no further action after Waymo conducted two significant recalls to address software issues affecting obstacle detection and avoidance [1]