TOYOTA Sienna Incident

The May Mobility vehicle (Ego) is stopped at a red light, then the Ego begins to accelerate and turn right when the traffic light changes to green. As the Ego accelerates, a pedestrian begins moving and enters the crosswalk from the other side of the intersection. This activates the rule-based crosswalk logic. Ego determines that it is able to stop before the crosswalk without exceeding our max deceleration threshold, which triggers an in-policy stopping reaction for the crosswalk. The Ego brakes to yield for the pedestrian. The vehicle trailing the Ego accelerates, making contact with the rear-end of the Ego. In the 2.5 seconds between the start of the Ego braking and the collision, the rear vehicle accelerated from 0.2 to 6.1 m/s (0.4 to 13.6 mph) without slowing until after the collision occurred. In response to this incident, immediate mitigations were made, in that the vehicle operators (AVOs) operate all intersections in manual mode. This remained in place until January 12, when we received a solution which instituted a reduction of the 3.5 m/s2 parameter, in order to prevent the Ego from yielding to pedestrians in crosswalks that are still far from the Ego’s lane if such yielding would induce braking.