Cruise turns left and stops right in path of oncoming vehicle resulting in collision

Incident

On 6/3/2022 at 11pm a Cruise robotaxi in autonomous mode was traveling eastbound on Geary Blvd. At Spruce St the Cruise vehicle entered the left-turn lane. On a green signal, it turned left across three lanes of traffic. The Cruise detected a Prius vehicle heading westbound, approaching in the curbside lane, and stopped in its path, resulting in a serious collision. Occupants of both vehicles were treated for reportedly minor injuries.

A software “fix” was made 3 days later to allegedly prevent this particular problem.

In rather poor timing, Cruise was granted permission by the CPUC the day before to charge passengers for rides.

News reports

There is some useful details covered in news reports, such as an overview of the incident, occupants of the vehicles, quotes from Phil Koopman, and Cruise not being transparent about the situation. It is noteworthy that the crash was not publicized until 7/7/22, over a month after the incident, and then only because Automative News discovered the incident by perusing DMV records. Cruise never provided useful information.

Collectively, Koopman said the incidents painted a problematic portrait.

“Everything is very concerning here,” he said. “With this crash in particular, there are a number of very concerning things upon a plain reading of the crash report. The onus should be on Cruise to prove they’re still safe to operate.“

Phil Koopman, CMU professor, in Automotive News

Police Report

At long last, the San Francisco Police Department provided a police incident report.

Speed Limit

The speed limit for that portion of Geary Blvd is indeed just 25mph. From the police report and statements from Cruise it appears that the Prius was speeding. But street design was also at fault.

Analysis by Retrospect

Michael Woon, CEO of Retrospect, did an excellent analysis of the crash. Their conclusion is that the Prius could not have possibly been going to turn right onto Spruce St. because doing so would violate the laws of physics. The Cruise vehicle should have correctly determined that the Prius was not going to turn right and act accordingly, thereby avoiding the collision.

Analysis by Brad Templeton

Brad Templeton, a long-time authority on Autonomous Vehicles, analyzed the crash in Forbes. Templeton explained that either the Cruise should not have stopped where it did or it should not have attempted the left turn at that time.

Analysis by Robotaxi.rodeo

There are two key issues with respect to this crash. The Cruise vehicle first made a dangerous and illegal left turn in front of approaching traffic. Though Cruise never publicly addressed this issue, it is actually the root cause of the crash and will be covered in depth here. The second issue is that after the Cruise vehicle committed to making a left turn, it made an incorrect decision and stopped directly in the path of the approaching Prius instead of simply continuing and avoiding the crash. These are both points that were also made in the analysis by Brad Templeton.

It was wrong to expect Prius to turn right

Both of these mistakes on the part of the Cruise vehicle were claimed in the reports to the DMV and NHTSA to be due to expecting the approaching Prius to turn right onto Spruce Street. Therefore the first thing to analyze is how that assumption was incorrect and did not take into account many factors.

Vehicle code allows vehicles parking to travel straight in transit lane

Section 601 of the San Francisco Vehicle Code specifically allows multiple vehicle types to use the transit lane even if they are not turning right. The vehicle code specifically excepts buses of all types (not just public transit buses) and taxis. But importantly, all vehicles are excepted if they are pulling into or out of a parking space or a driveway.

SEC. 601. DESIGNATED TRANSIT-ONLY AREAS.

   (a)   The locations listed in this Section 601 are designated as Transit-only Areas. Any vehicle operating within a Transit-only Area during times that the Transit-only Area is enforced is in violation of Transportation Code, Division I, Section 7.2.72 (Driving in Transit-only Area).

…

2 ²    Other Transit-Only Areas. Except for buses, taxicabs, vehicles preparing to make a turn, vehicles entering into or exiting from a stopped position at the curb, and vehicles entering into or exiting from a driveway, no vehicle may operate in the following Transit-only Areas during the times indicated:

All Times

Geary Blvd.

14th Ave.

Collins St.

San Francisco Traffic Code Section 601

Taxis allowed to go straight in transit lane, including Prius taxis

In San Francisco a Prius can be a taxi, and taxis are explicitly allowed in the transit lanes and do not need to turn right from them. The Cruise system surely cannot differentiate between taxis and regular vehicles, especially given the large number of Prius taxis in use. Even if the Cruise system can identify the vehicle type, it still cannot determine if the vehicle is allowed to drive straight through a transit lane.

Could have been a Fire Department vehicle

Even the San Francisco Fire Department uses Prius vehicles, which means that such vehicles might be allowed to travel straight in a transit lane.

Other city vehicles look like regular vehicles

San Francisco police cars look like ordinary vehicles and could not be differentiated by the Cruise ADS. And of course police vehicles are allowed in and do use transit lanes.

Regular vehicles do use the transit lane inappropriately

While most vehicles are not allowed in the transit lanes, it is unfortunately still common for vehicles to not always follow the laws. To verify this we simply looked at Google Map Satellite View snapshot of the transit lanes on Geary and O’Farrell. Quickly we were able to find two examples of where vehicles were improperly using the transit lanes. This clearly indicates that one cannot assume that a vehicle is going to turn right at the intersection just because it is in the transit lane. Perhaps most of the time the vehicle would turn right, but there is a significant percentage of times when the vehicle will go straight, even though not allowed to. Any automatic vehicle system must take lack of compliance with vehicle laws into account.

Turning right would have defied laws of physics

As described in the detailed analysis by Retrospective, if the Prius was speeding as claimed by Cruise then the vehicle could not have turned right onto narrow Spruce St. The Cruise system should have been able to determine that the Prius was not going to turn, and should have planned accordingly.

And note in the Google Maps satellite image below that Spruce Street is quite narrow, only 28′ from curb to curb, cars parked on both sides, and only 15′ for two directions of vehicle travel. This is inherently a very slow street, and a vehicle turning onto it from Geary Blvd would have to make the turn quite slowly, thereby not posing a risk for colliding with the Cruise.

Summary of vehicle turning right issue

Given the many possibilities, there was a significant chance that the approaching Prius vehicle was going to continue straight instead of turning right onto Spruce Street. All decisions made by the Cruise planner should have taken this possibility, even high probability, into account. But it did not. Also, all statements and filings with regulators should have made it clear that concluding that the Prius was going to turn right was not correct.

Cruise unsafe left turn

The law says that one must yield the right-of-way to approaching traffic until one can complete the turn safely.

21801. (a) The driver of a vehicle intending to turn to the left or to complete a U-turn upon a highway, or to turn left into public or private property, or an alley, shall yield the right-of-way to all vehicles approaching from the opposite direction which are close enough to constitute a hazard at any time during the turning movement, and shall continue to yield the right-of-way to the approaching vehicles until the left turn or U-turn can be made with reasonable safety.

California Vehicle Code 21801

Since the Prius vehicle was approaching from the opposite direction on Geary, it is clear that the Cruise vehicle dangerously and illegally did not yield the right-of-way and that the left turn was made in a very unsafe manner. Since there was a significant probably that the Prius was heading straight instead of turning, creating a plan based on the Prius turning was incorrect and dangerous. The analysis by Templeton reenforces this conclusion.

It is especially glaring that there was a very simple solution for easily and safely avoiding the approaching Prius: follow the vehicle code and just wait until the road was clear of approaching vehicles, and only then turn left. Given the 11pm time of the crash, there would have been a low volume of vehicles on Geary Blvd. Waiting for a safe time to turn would have only added a few seconds to the trip. And if there was a great deal of traffic the Cruise could have simply waited for the traffic signal on Geary Blvd to turn yellow, which would stop the approaching vehicles, and then turn left safely. That the safe option was not taken is extremely problematic and indicates that there was not a true “safety first” culture at Cruise.

Unsafe stopping in path of approaching Prius

Cruise never provided pictures, video, or other demonstrable evidence of exactly how the crash occurred to either the public, the news, or the regulators. Fortunately we can still piece together what happened.

In the Cruise statement to the NHTSA they claim that the ADS predicted that the Prius would hit the front of the Cruise, and therefore the Cruise initiated hard braking. But Cruise states that then the Prius “suddenly” moved out of the right-hand lane and proceeded straight through the intersection instead of turning right. If the Cruise statement is accurate then it means the Prius entered the intersection in either the right-hand lane, in the 2nd-lane, or somewhere in between. This is shown in the diagram below.

The location of the Cruise at impact must be a bit to the north of the Prius since the impact areas shown in the DMV report show that only the rear half of the right side of the Cruise was damaged.

Since the front of the stopped Cruise vehicle was a half a car length (half of 13.5′) north of the Prius, the location of the Cruise when it was hit by the Prius blocked at least half of the right-hand lane, as shown in the diagram below. Note that the travel lanes are 10′ wide, a Chevy Bolt Cruise vehicle is 13.5′ long, and the Prius is 6′ wide.

The conclusion is that when the Cruise stopped it ended up blocking at least half of the right-hand lane, making a collision inevitable if the Prius did not move out of that lane. The Prius likely tried to avoid the collision by moving towards the 2nd lane, but given the 13.5′ length of the Cruise a collision could still not be avoided. The Cruise had stopped in exactly the wrong place such that whether the Prius went straight or tried to go around the Cruise, a collision was still inevitable.

The Cruise vehicle should not have predicted that it needed to stop in order to avoid a collision because doing so actually made the collision inevitable.

The Cruise statement that a collision was predicted for unless the Cruise vehicle stopped is not credible. Only the rear half of the vehicle, approximately 6.5′, was impacted by the crash. If the Cruise would have continued to move forward it would have easily cleared out of the way of the Prius. It appears that the actual behavior of the Cruise was to do an emergency stop since the strong possibility of a collision was detected. This is exactly the dangerous behavior experienced in other situations, such as the crash at Mission St & 26th St shown in the video below.

And since the Cruise vehicle ended up blocking at least part of the right-hand lane, the issue of whether or not the Prius was turning right is not relevant. If the Prius was going to turn right then both vehicles would have been in the right-hand lane, resulting in a collision, regardless. Plus if the Prius was turning right then it would have slowed down considerably, which would have given the Cruise plenty of time to continue moving and get out of the way instead of stopping and causing the collision.

Untruths

Cruise really tried to limit information on this crash. And when they did provide information it was often false or at least very misleading.

Cruise:

• Did not publicize the crash or inform the public in any way. It was only discovered because Automotive News looked through DMV crash reports a month later.
• As indicated by the police report, Cruise did not provide details of the crash to the police when requested to do so. This caused incorrect interpretation of the crash.
• Did not answer reporter’s further questions.
• Claimed that the Prius was in a bus or right-turn-only lane, which it was not. That lane can also be used by taxis and for when pulling in or out of a curb parking space or driveways.
• Never acknowledged that a significant percentage of vehicles in a transit lane will continue straight through an intersection, even if not legal to do so.
• Mislead regulators by stating that the problem was their system predicting that the Prius was going to make a right turn. But the collision would have occurred even if the Prius had turned right. The whole issue of the Prius turning right appears to be intended to draw attention away from the Cruise vehicle stopping dangerously in the path of the Prius.
• Emphasized to reporters that the Cruise vehicle did not get a ticket by the police, falsely implying that it was not at fault. Cruise of course knows that in California moving violations can only be given to human drivers, not to autonomous vehicles. Not receiving a ticket in no way indicates that the robotaxi was not at fault.
• Emphasized their unverified claim that the Prius was speeding, yet the speed of the Prius was not actually a factor in the collision. The focus on the speed of the Prius was clearly an attempt to deflect blame onto the Prius human driver.
• Never acknowledged that the root problem was the Cruise vehicle prematurely attempting the left turn instead of waiting for a safe interval.
• Claimed to have fixed the problem, but they did not since a root problem was making the left turn improperly in front of an oncoming vehicle.
• Never acknowledged that stopping directly in the path of the Prius was the most dangerous possible maneuver.
• Blamed the other vehicle by stating the collision occurred due to “oncoming vehicle’s sudden change of direction.” But this is false. Yes, the Prius might have had a sudden change of direction, but the collision occurred because the Cruise vehicle stopped in front of the path of the Prius. The Prius then had to suddenly change direction to try as much as possible to avoid the collision.

Conclusions

The Cruise driving system failed twice, first by making an unsafe left turn into approaching traffic, and then by dangerously stopping in the path of the approaching vehicle.

The Cruise system expecting the Prius to turn right was incorrect and part of their problem, if that indeed was the cause of the actions taken by the Cruise vehicle. It is extremely problematic that the Cruise system did not take into account the many factors that indicated that the Prius had a significant probability of continuing straight instead of turning. Such a lack of understanding of real-world traffic situations is likely to cause problems in other complicated situations. Also, even if the Prius was going to turn right, the Cruise vehicle stopping would have still caused a collision.

It appears that after committing to making the unsafe left turn the Cruise vehicle stopped like a “deer in the headlights” in the path of the Prius, instead of simply continuing forward out of harm’s way. This behavior is not safe for the deer, and it is not safe for autonomous vehicles.

Cruise has not indicated that they addressed the multiple problems that actually caused the crash. Given that their vehicles continued in other situations to stop directly in the path of a rapidly approaching vehicle shows that they indeed have not addressed these core issues even though they did a “recall” of the vehicles to update their software.

It is also deeply disturbing that Cruise misrepresented or hid many of the details of the cause of the crash to the regulators and to the public. This behavior implies a culture of “move fast and break things” as opposed to a culture of safety.