Some believe that drivers are to cars as fish are to bicycles, and the state of Nevada has agreed and passed a bill this week approving driverless vehicles on its roads.

Assembly Bill 511, the first such legislation in the country, allows the state’s Department of Transportation to draw up rules that would authorize driverless cars. The regulations would include safety standards, insurance requirements and testing sites.

A driverless car is defined by the bill as using “artificial intelligence, sensors and global positioning system coordinates to drive itself without the active intervention of a human operator.” That includes technology such as lasers, cameras and radar.

So far, such driverless cars have logged more than 140,000 miles on California roads as part of a Google endeavor.

Stanford University robotics professor Sebastian Thrun, a project leader on Google’s effort, said that nearly all driving accidents are due to human error rather than mistakes by machines.

"Do you realize that we could change the capacity of highways by a factor of two or three if we didn't rely on human precision on staying in the lane but on robotic precision, and thereby drive a little bit closer together on a little bit narrower lanes and do away with all traffic jams on highways," he said in a speech at the TED 2011 conference in Long Beach this spring.

In Europe, efforts are underway to create “car platoons,” in which drivers could hook their vehicles up electronically with others to form a chain controlled by the first vehicle in the line.

The SARTRE project, which stands for Safe Road Trains for the Environment, envisions convoys of cars led by a professional driver in front, allowing drivers in the back to kick back and relax. Wirelessly controlling the distance and speed between cars in the caravan can cut back on accidents, improve fuel efficiency and limit congestion, researchers believe.