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The Bolt reportedly aborted a lane change and swerved back into its previous position, hitting a motorcycle that shifted into the spot.

An autonomous Chevrolet Bolt has been involved in a minor accident, colliding with a motorcycle while driving on San Francisco streets.

The Bolt was in the center of three one-way lanes on Oak Street past the intersection with Fillmore. The EV identified a space between two vehicles in the left lane and began to merge into that lane, however the system aborted the maneuver after sensing that the leading vehicle began to decelerate.

"As the Cruise AV was re-centering itself in the lane, a motorcycle that had just lane-spit between two vehicles in the center and right lanes moved into the center lane, glanced the side of the Cruise AV, wobbled , and fell over," the company wrote in its official accident report filed with the DMV.

The accident has been blamed on the motorcycle "for attempting to overtake and pass another vehicle on the right under conditions that did not permit that movement in safety," the filing adds. The Bolt was driving at 12 mph while the bike was traveling 17 mph, according to the filing.

The motorcyclist is said to have walked away but reported shoulder pain and was taken for medical care.

GM appears confident that the motorcyclist was solely at fault, but the accident leaves a few open questions about the autonomous vehicle's role. Self-driving cars will be expected to avoid certain collisions even if not at fault. GM has not disclosed technical details of the motorcycle accident, such as the computer's detection of potential conflicts with both the motorcycle to the right and a vehicle to the left.

Depending on the specific details, a human driver may have attempted several different strategies to avoid an accident altogether. Perhaps the Bolt could have more aggressively completed its intended lane change as the gap began to close; swerved back to the right just enough to miss the car in the left lane and leave room for the bike; applied the brakes to let the bike clear before 're-centering;' or used the horn in an attempt to alert the motorcycle rider.

The car was operated by Cruise Automation, a startup purchased by GM for $500 million in 2016 but left as a standalone business based in San Francisco. The company views the city as the perfect place to test autonomous drive systems, presenting a much higher challenge than certain other cities.

Cruise, like other autonomous development projects from major automakers, appears to lag far behind Waymo in developing software necessary for fully autonomous operation. Google's self-driving car project has benefited from four million miles on the road. Perhaps more importantly, the company's coding wizards have created a simulation system that accumulated 2.5 billion virtual miles last year alone.

Waymo has also tested its system on a private 91-acre facility a few hours from San Francisco, where "rare and unusual" situations include people jumping out of canvas bags or skateboarders lying on their boards. Engineers can then perform simulations that explore vehicle behavior as many different variables change slightly, such as the speed and position of vehicles and pedestrians at an intersection.

The California DMV has received nearly two dozen autonomous vehicle accident reports from GM Cruise this year. Google and Waymo account for another three reports. No equivalent data is available for Waymo's primary public testing operations based in Phoenix, however.