Self-driving cars hit winter roads

General Motors has started testing fully autonomous vehicles on public roads around its technical centre in suburban Detroit.

The announcement came a week after Gov. Rick Snyder signed legislation that allows the cars to be tested on public roads without a driver or a steering wheel.

But the automaker says that for now, it will have human backup drivers for its fleet of autonomous Chevrolet Bolt electric cars.

Testing has started on roads near the automaker’s technical centre in Warren, Mich. The Bolts will soon move to the entire Detroit metro area, which will serve as the company’s main testing grounds for snowy and cold weather.

Weather is one of the biggest obstacles to autonomous cars because snow can stop cameras and other sensors from spotting critical things such as lane lines and traffic signals. GM’s other public-road testing sites are in San Francisco and Scottsdale, Ariz. It’s running about 40 autonomous Bolts in tests.

CEO Mary Barra also announced GM will build next year an unspecified number of fully autonomous Bolts on the assembly line where regular Bolts are made, to gain expertise in building such vehicles.

GM had been testing autonomous Bolts on the sprawling technical centre grounds for the past few weeks, but wanted to move to public roads soon after the law became effective to take advantage of the weather.

Executives wouldn’t say when GM would start testing without a human driver.

GM also wants to start running a fleet of autonomous taxis that could be called by passengers