Google’s self driving car hit a bus

Google’s self driving car was in another accident, but this is the first time the autonomous car was at fault. The self driving cars been involved in accidents, but the cars were always innocent bystanders, mainly being hit from the rear. The company filed a California DMV accident report confirming that one of its autonomous vehicles (a Lexus RX450h) collided with a bus in Mountain View.

The car and bus involved both assumed incorrectly assumed where they were in proportion to each other. The accident reports states the self driving car was going to make a right turn by hugging the curb, but sand bags were blocking a storm drain and the direct path to turn. The car than tried to move around the hazard by entering the next lane slightly. The car saw the bus but assumed the bus would yield to the car, however it failed to. The bus was traveling 15mph and the car was going 2mph, so far from a massive crash like many sites have tried to make it sound. The cars front fender, wheel and sensor in the were damaged in the process. Making this accident one of the first at fault accidents and one with more damage than others.

While a minor accident it brings the question up of the ethics question. Experts have questioned if Google’s car can choose between hitting a shopping cart or a stroller with a baby. It’s a lose lose situation, but its something we know a human would hit the shopping cart over a stroller. In this case Google’s software assumed too much in this situation, but many could say the bus driver was the reason Google’s car had the accident. If the bus was a self driving car it would have likely yielded to the car.

Google’s statement however makes the accident sound like its mutual fault:

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.

Tell us in the comments below what you think about Google’s self driving cars!



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