Safety Analysis of Two Cruise Robotaxi Pedestrian Injuries
Cruise has now had two pedestrian injuries in San Francisco, with the more severe one being complicated because it involved a pedestrian first hit by another vehicle. NHTSA has launched an investigation based on those injuries and at least two other public video reports of close encounters. This makes available the relevant crash reports, so we have more direct information about what happened. The question asked in this piece is what can be done to avoid similar crashes in the future.
On a numbers basis, two pedestrian injuries in a span of fewer than six weeks for a fleet of a couple hundred vehicles in San Francisco is a concern, so this is worth some analysis based on available information.
- First injury: Aug. 26, 2023. A pedestrian stepped off the curb into a crosswalk right in front of a Cruise vehicle at the change of a traffic light. The Cruise swerved, then braked. Impact at 1.4 mph. Pedestrian transported by EMS.
- Second injury: Oct 2, 2023. A pedestrian crosses on the opposite side of a cross-street in front of the Cruise vehicle and another vehicle next to it. Both vehicles proceeded through the intersection as a pedestrian was in a crosswalk across their paths. The other vehicle struck the pedestrian at an undisclosed speed, who was then run over by the Cruise vehicle and trapped under it with severe injuries.
First Pedestrian Crash
- Were there obvious contextual clues that the pedestrian would attempt a last second crossing? What are common cases, and are they covered by the Cruise AV design?
- Why did the vehicle swerve before stopping instead of doing both at once?
- Could/should the Cruise vehicle have followed a less aggressive acceleration profile given the likely risk of a pedestrian entry into the crosswalk in that type of circumstance?
Second Pedestrian Crash
- There are two vehicles starting through an intersection, side by side, with two lanes in that direction of travel. From a top view the other, human driven, dark-colored vehicle is on the left (faster lane) and the lighter-colored Cruise is on the right (curb lane).
- A pedestrian is walking across the far side of the intersection in the crosswalk. At the same time, both vehicles accelerate into the intersection. The most likely situation is the Cruise vehicle was a bit behind the other vehicle (although this is an educated guess based on the description of the events).
- Cruise says the pedestrian entered the crosswalk after the light changed, crossed in front of the Cruise vehicle, then stopped in the other vehicle's lane. The other driver presumably thought the pedestrian would clear the travel lane in time, and did not slow down.
- The other vehicle hit the pedestrian. Cruise says the pedestrian was deflected back into the Cruise vehicle's lane.
- The Cruise vehicle "braked aggressively" in response to a surprise pedestrian appearing in its lane, but hit the pedestrian shortly after.
- The Cruise vehicle had sufficient forward speed that it ran over the pedestrian and came to a stop with the pedestrian trapped under the rear axle. Both of the pedestrian's feet protruded from under the vehicle by the left rear tire, with that tire on top of one leg. (Photo link below.)
- The pedestrian was severely injured by a combination of the two vehicle strikes. Information about the ultimate outcome for that pedestrian is not currently available, although we hope that a recover is quick and as complete as possible.
California Rules of the Road have an interesting requirement for crosswalks:
"(c) The driver of a vehicle approaching a pedestrian within any marked or unmarked crosswalk shall exercise all due care and shall reduce the speed of the vehicle or take any other action relating to the operation of the vehicle as necessary to safeguard the safety of the pedestrian." (emphasis added)
It is interesting to ask if the Cruise vehicle actually exhibited "all due care." It likely did not reduce speed from its normal green light acceleration, or Cruise would have taken credit for having done so. (If they want to provide more details I will gladly update this statement.)
Of note is the Cruise position that their vehicle stopped as quickly as possible once the pedestrian was in their lane, in effect claiming the collision was unavoidable. But that position is not necessarily true in the larger context, especially if one learns from this crash for the next potential pedestrian crosswalk collision. The question is when the Cruise AV could have stopped. There are at least three possible decision points for stopping to avoid this collision with the pedestrian, and the Cruise vehicle appears not to have exercised the first two:
- The light changes green, but there is a pedestrian still in the crosswalk in the Cruise vehicle's direction of travel in front of the Cruise vehicle. Did it slow down? Or execute a normal acceleration because it predicted the pedestrian would be clear by the time it got there? A prudent human driver would have waited, or more likely crept forward while waiting to signal cars behind it not to honk for failing to recognize a green light.
- The pedestrian clears the Cruise lane, but the Cruise vehicle clearly sees the pedestrian about to be hit by the adjacent vehicle. The Cruise vehicle could have (I would argue should have) stopped to avoid being close to an injury event. Expecting it to predict a pedestrian collision trajectory is asking a lot -- but it should have stopped precisely because it cannot predict what will happen after such a collision. Safety demands not going fast past a pedestrian who is about to be hit by another vehicle in an adjacent lane. But this is precisely what the Cruise vehicle did.
- The pedestrian lands in the Cruise lane and the Cruise vehicle has not slowed down yet. By then it is too late, and it runs over the pedestrian. This could likely have been avoided by a prudent driving strategy that addresses the previous two decision points.
The Redacted Confidential Business Information
"The AV detected a collision, bringing the vehicle to a stop; then attempted to pull over to avoid causing further road safety issues, pulling the individual forward approximately 20 feet."
Calling Emergency Services
Cruise Safety Record
- News photo of pedestrian trapped under vehicle.
- Investigation summary: https://static.nhtsa.gov/odi/inv/2023/INOA-PE23018-11587.pdf
- Interesting note: apparently there just under 1000 Cruise robotaxi vehicles
- Pedestrian crash report for 8/26/2023: https://static.nhtsa.gov/odi/inv/2023/INOT-PE23018-11584P2.pdf
- Pedestrian crash report for 10/2/203: https://static.nhtsa.gov/odi/inv/2023/INOT-PE23018-11585P2.pdf