.

This graphic shows how cars wil communicate with road signals and each other, and use sensors to detect hazards such as pedestrians.

Related Stories

• Driverless car beats Berlin traffic
• Crash-evading cars on the horizon

Cars that can drive themselves will be commercially available by 2020, says General Motors - and they will be safer than if humans were driving them.

GM vice-president for research and development Alan Taub told the Intelligent Transport Systems World Congress in Orlando on Sunday that active safety systems such as sensors, radars, portable communication devices, GPS and cameras would provide critical information to the driver and the car's computer system - and, combined with digital maps, the same technologies would allow the driver to let the vehicle concentrate on driving while he does something else.

Taub said: "The primary goal, however, is safety. Future safety systems will prevent crashes by intervening on behalf of drivers before they're even aware of a hazardous situation."

GM is already putting some of these safety systems into its vehicles. Lane departure warning is available on the Chevrolet Equinox and GMC Terrain, while blind-spot alert is available on the Cadillac Escalade, Buick LaCrosse, GMC Yukon and Chevrolet Tahoe and Suburban. A number of models, including the Equinox and Terrain, have reversing cameras.

But it's the next-generation safety systems now being developed that will provide the foundation for autonomous driving.

The first, already available on the 2012 GMC Terrain, uses a high-resolution digital camera mounted on the windshield ahead of the rearview mirror to look for shapes of vehicles and lane markings, alerting the driver to possible collisions and lane departures.

Then, vehicle-to-vehicle and vehicle-to-infrastructure communication systems that gather information from other vehicles, roads and traffic signals will warn drivers about possible hazards ahead, including slowed or stalled vehicles, hard-braking drivers, slippery roads, sharp curves and upcoming stop signs and intersections.

These systems, on display this week at the ITS congress, can be installed in the vehicle or downloaded as apps to tablets or smartphones that connect wirelessly to the car.

Finally, the EN-V urban mobility concept will combine GPS with vehicle-to-vehicle communications and distance-sensing to enable autonomous driving.

Its capabilities will include pedestrian detection, collision avoidance, platooning and automated parking and retrieval, where the car drops off its driver, parks itself and then returns to pick up the driver via commands from a smartphone.

Taub said: "We believe the industry will experience a dramatic leap in active safety systems in the coming years and, we hope, a decline in injuries and fatalities on our roads."

GM has been working with Carnegie Mellon University to develop autonomous vehicle technology since 2007, when the university built "The Boss", an autonomous Chevrolet Tahoe that won that year's DARPA urban challenge, which required the driverless vehicles to drive in traffic and perform complex manoeuvres such as overtaking, parking and negotiating intersections over a 96km course.