Driverless cars are not only getting better at racing, they also drive more efficiently. They react faster and therefore require shorter safety distances. This increases the number of cars that can drive on a given road. A group of researchers from Columbia University have calculated the potential capacity increases and have shown that autonomous cars could greatly increase highway capacity. If cars are able communicate with each other and negotiate their speed and safety distance, highway capacity could increase by up to a factor of 4!
This could translate into great savings for infrastructure expenditures. Annual spending for highway infrastructure alone in the United States amounts to approximately 150 billion U$! Great savings could also be realized in developing countries with fast-growing road networks.
The paper systematically models different cases of capacity utilization and calculates the distances required between cars at different speeds and for different mixes of cars being operated by human drivers, running in autonomous, sensor-based mode or driving in connected mode. They find that the optimum capacity increase occurs when all cars are linked electronically. Just a few cars that are able to communicate makes little difference however. This is different for sensor-based, non-communicating autonomous cars. Even a few such cars would increase road capacity.
The paper provides great insights for anyone interested in the economic implications of autonomous car technologies. Investments in this technology have great potential of reducing road infrastructure expenditures.
Source: Tientrakol, P.; Ho, Y.-.C and Maxemchuk, N.F.: Highway capacity benefits from using vehicle to vehicle communication and sensors for collision avoidance. Vehicular Technology Conference, 2011. (url)