Grouping vehicles into platoons is one proposed method to increase road capacity without building additional traffic lanes.
Platoons decrease the distances between cars using electronic, and possibly mechanical, coupling. This capability would allow many carss to accelerate or brake simultaneously. Instead of waiting after a light changes to green for drivers ahead to react, a synchronized platoon would move as one, allowing up to a fivefold increase in traffic throughput.
Platoon capability might require buying new cars, or it may be something that can be retrofitted. Drivers would probably need a special license endorsement on account of the new skills required and the added responsibility when driving in the lead.
Smart cars with artificial intelligence could automatically join and leave platoons. The automated highway system is a proposal for one such system, where cars organise themselves into platoons of eight to twenty-five.
See also: Future of the car