Lexus RX450h Incident

On Friday April [XXX] at 16:16 local time, the May shuttle was driving Westbound on [XXX] in Ann Arbor, MI in autonomous mode and was followed by another vehicle. The following vehicle was traveling approximately twice as fast as the May shuttle and catching up to the May shuttle from behind. The May shuttle began to slow for traffic ahead, which was stopping for a red light, but the following vehicle did not decelerate. While slowing, the May shuttle identified a bollard on the side of the road as a likely pedestrian and added a safety buffer which intersected with the predicted trajectory of the shuttle. This caused the shuttle to increase deceleration to avoid the projected collision with the buffer. The following vehicle started braking late and impacted the May shuttle from behind with a relative velocity of 6.2 m/s. Re-simulation of this event with a future software version shows that the May shuttle would have decelerated less abruptly.