Could self-driving cars mean an end to traffic jams?

According to a recent study, the presence of just a few autonomous vehicles can eliminate the stop-and-go driving of the human drivers in traffic.

The University of Illinois finding indicated that self-driving cars and related technology may be even closer to revolutionizing traffic control than previously thought.

Lead researcher Daniel B. Work said that the experiments show that with as few as 5 percent of vehicles being automated and carefully controlled, we can eliminate stop-and-go waves caused by human driving behaviour.

The use of autonomous vehicles to regulate traffic flow is the next innovation in the rapidly evolving science of traffic monitoring and control, Work said. Just as fixed traffic sensors have been replaced by crowd-sourced GPS data in many navigation systems, the use of self-driving cars is poised to replace classical freeway traffic control concepts like variable speed limits. Critical to the success of this innovation is a deeper understanding of the dynamic between these autonomous vehicles and the human drivers on the road.

The team conducted field experiments in Tucson, Arizona, in which a single autonomous vehicle circled a track continuously with at least 20 other human-driven cars. Under normal circumstances, human drivers naturally create stop-and-go traffic, even in the absence of bottlenecks, lane changes, merges or other disruptions, Work said. This phenomenon is called the "phantom traffic jam."

Researchers found that by controlling the pace of the autonomous car in the study, they were able to smooth out the traffic flow for all the cars. For the first time, researchers demonstrated experimentally that even a small percentage of such vehicles can have a significant impact on the road, eliminating waves and reducing the total fuel consumption by up to 40 percent. Moreover, the researchers found that conceptually simple and easy to implement control strategies can achieve the goal.

This latest research suggested that even the related technology available now - such as adaptive cruise control - has the power to improve traffic even before there are large numbers of autonomous vehicles on the road.

The near future with only a few autonomous vehicles on the road is more challenging than the far future in which all vehicles are connected, Seibold said.

The researchers say the next step will be to study the impact of autonomous vehicles in denser traffic with more freedom granted to the human drivers, such as the ability to change lanes.