A crash involving a self-driving car and a municipal bus has prompted Google, which is testing the autonomous technology, to admit ‘some responsibility’ for the mishap.
The crash, which took place on 14 February in California, is thought to have been the first example of Google’s technology being at fault during such an incident.
The search giant later said it has made changes to its software following the crash to avoid such accidents in future.
In a filing with California regulators, Google said the autonomous vehicle was traveling at less than two miles per hour, while the bus was moving at about 15 miles per hour.
Its self-driving Lexus RX450h was attempting to move around some sandbags in a wide lane at the time.
The vehicle and the test driver "believed the bus would slow or allow the Google (autonomous vehicle) to continue," it said.
But three seconds later, as the Google car in autonomous mode re-entered the center of the lane, it struck the side of the bus, causing damage to the left front fender, front wheel and a driver side sensor. No one was injured in the car or on the bus.
In a statement, Google said: "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."
The Santa Clara Valley Transportation Authority will investigate the circumstances of the accident, said Stacey Hendler Ross, a spokeswoman for the body.
She said the Google car caused minor damage to the bus, striking the pivoting joint, or flexible area in the middle of the articulated bus. After the crash, 15 passengers on the bus were transferred to another bus. An investigation to determine liability is pending.
John M. Simpson, privacy project director for advocacy group Consumer Watchdog, said the crash "is more proof that robot car technology is not ready for auto pilot."
A spokesman for the California Department of Motor Vehicles (DMV) said it will speak to Google to gather additional information, but added ‘the DMV is not responsible for determining fault’.
The cars’ driving algorithms have now been reprogrammed to more deeply understand that buses and other large vehicles are less likely to make way than other types of vehicles.
“We hope to handle situations like this more gracefully in the future," Google said.
The incident is not the first experienced by Google’s self-driving cars. In November, one of the vehicles was stopped by police for driving too slowly.
Jonathan Hewett, head of strategy for Octo Telematics, which makes the driving analysis technology found in black boxes for car insurance companies such as Admiral, said the accident shows that autonomous vehicles still have some way to go before being ready for public rollout.
“The recent crash … demonstrates that we still have numerous hurdles to overcome on the path to a driverless future,” he said.
“Experts acknowledge it could be decades before regulators allow vehicles to be built without manual controls, and it is possible that during the transition period when conventional and self-driving vehicles would share the road, safety might actually worsen.
“As autonomous cars are driven by navigational data provided by a series of sensors, any accident will require software and hardware analysis to understand why it occurred and analogous to ‘black box’ flight recorders in aviation.”