Well, it happened. Google’s Skynet, or self-driving car, had a minor fender-bender. No one was hurt in the autonomous Lexus versus bus accident, but it makes for headlines filled with ‘see, we can’t let a car drive itself.’

Really? Over a minor accident? Context is crucial here. In the DMV report found by Mark Harris, a Google autonomous Lexus was stopped in Mountain View at an intersection on February 14.

The car needed to maneuver around sandbags placed in the right-hand lane. The car assumed (that’s a mistake) as it edged back into traffic, the slowing bus coming behind it would allow it to merge.

Google…

No one on the autonomous vehicle staff thought to program the car with the fact humans can’t drive? The bus ended up striking the Lexus, causing “sustained body damage to the left front fender, the left front wheel and one of its driver’s-side sensors.”

google self driving lexus

How does Google explain the accident? Stuff happens. Here’s the more corporate PR rationale behind the accident in Google’s monthly report on the self-driving project.

Google Self-Driving Car Project Response

Our self-driving cars spend a lot of time on El Camino Real, a wide boulevard of three lanes in each direction that runs through Google’s hometown of Mountain View and up the peninsula along San Francisco Bay. With hundreds of sets of traffic lights and hundreds more intersections, this busy and historic artery has helped us learn a lot over the years. And on Valentine’s Day we ran into a tricky set of circumstances on El Camino that’s helped us improve an important skill for navigating similar roads.

El Camino has quite a few right-hand lanes wide enough to allow two lines of traffic. Most of the time it makes sense to drive in the middle of a lane. But when you’re teeing up a right-hand turn in a lane wide enough to handle two streams of traffic, annoyed traffic stacks up behind you. So several weeks ago we began giving the self-driving car the capabilities it needs to do what human drivers do: hug the rightmost side of the lane. This is the social norm because a turning vehicle often has to pause and wait for pedestrians; hugging the curb allows other drivers to continue on their way by passing on the left. It’s vital for us to develop advanced skills that respect not just the letter of the traffic code but the spirit of the road.

On February 14, our vehicle was driving autonomously and had pulled toward the right-hand curb to prepare for a right turn. It then detected sandbags near a storm drain blocking its path, so it needed to come to a stop. After waiting for some other vehicles to pass, our vehicle, still in autonomous mode, began angling back toward the center of the lane at around 2 mph — and made contact with the side of a passing bus traveling at 15 mph. Our car had detected the approaching bus, but predicted that it would yield to us because we were ahead of it. (You can read the details below in the report we submitted to the CA DMV.)

Our test driver, who had been watching the bus in the mirror, also expected the bus to slow or stop. And we can imagine the bus driver assumed we were going to stay put. Unfortunately, all these assumptions led us to the same spot in the lane at the same time. This type of misunderstanding happens between human drivers on the road every day.

This is a classic example of the negotiation that’s a normal part of driving — we’re all trying to predict each other’s movements. In this case, we clearly bear some responsibility, because if our car hadn’t moved there wouldn’t have been a collision. That said, our test driver believed the bus was going to slow or stop to allow us to merge into the traffic, and that there would be sufficient space to do that.

We’ve now reviewed this incident (and thousands of variations on it) in our simulator in detail and made refinements to our software. From now on, our cars will more deeply understand that buses (and other large vehicles) are less likely to yield to us than other types of vehicles, and we hope to handle situations like this more gracefully in the future.

Right on with the ‘bear some responsibility.’ At a transportation event hosted by the LA Times, the self-driving project lead, Chris Urmson, spoke about safety being paramount to the project.

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That didn’t stop the handwringing questions surrounding the project. Urmson answered questions from the audience who were worried about the swarm of Google cars hitting the streets causing mass panic.

One of the questions was the famous trolley dilemma – ‘how many kids would you kill?’ ethical issue. The odds of something like that happening are rare, and Urmson spoke about how Google is building safeguards to further protect against that particular situation. “We try hardest to avoid unprotected road users.”

Where does Google go from here? Would the streets be safer if all the cars on the road were self-driving? Maybe, but Urmson’s point is that even one self-driving car improves the safety of humans around it.

“Having one of them on the road makes that person safer and makes everyone around them safer.”

Well, except when the autonomous car meets a city bus.

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