You might not think so from the traffic, but U.S. highways could nearly triple their capacity without any new construction. All the nation would have to do is turn to all-robotic cars.
If all the vehicles in the U.S. communicated with each other and used automated braking, existing highways could handle 273 percent more cars, according to a new study. The increase would come from smaller gaps between cars, as self-driving systems are able to react much more quickly than human drivers, so they don't need as much lead space. Right now, human drivers space themselves such that on highway at full capacity, vehicles take up only 5 percent of the road space, according to the California PATH Program.
It may take a while for all vehicles in the U.S. to get automated, however. No totally robotic cars are commercially available yet. Even after such products appear on the market, it will take time for all current car owners to replace their old models.
So, the Columbia study also examined how highway capacity will increase as the number of self-driving cars on the roads increases. Electrical engineers' magazine IEEE Spectrum has some graphs showing that highway capacity will start rising sharply after about 70 or 80 percent of American cars are equipped with vehicle-to-vehicle communication technology.
Such innovations are well on their way to American roads. The U.S. Department of Transportation recently launched the world's largest-ever test of vehicle-to-vehicle communication, with 3,000 networked cars in Ann Arbor, Mich.