According to Daniel Work, assistant professor of civil environmental engineering at the University of Illinois, The use of autonomous vehicles to regulate traffic flow is the next innovation in the rapidly evolving science of traffic monitoring and control. Image credit: John de Dios

Adding just a few self-driving cars to the road can make a difference in stop-and-go traffic, according to recent experiments funded by the National Science Foundation's Cyber-Physical Systems program and led by a multi-disciplinary team of researchers with expertise in traffic flow theory, control theory, robotics, cyber-physical systems and transportation engineering.

"Our 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 behavior," said Daniel B. Work, assistant professor at the University of Illinois at Urbana-Champaign, a lead researcher in the study.

Conducting the experiments in Tucson, Arizona, an autonomous vehicle continuously circled a track along with 20 human-operated cars. The simple addition of the one autonomous car keeping a controlled pace was responsible for smoothing traffic flow and avoiding “phantom traffic jams,” a phenomenon where human drivers naturally cause stop-and-go traffic, even without causes such as bottlenecks and lane changes.

Researchers believe that by just adding a small number of autonomous vehicles to regular traffic could impact stop-and-go traffic and thus reduce fuel consumption by up to 40 percent. Researchers also believe that the addition of autonomous vehicles may eventually replace traditional traffic control concepts such as variable speed limits.

"Fully autonomous vehicles in common traffic may be still far away in the future due to many technological, market and policy constraints," said Benedetto Piccoli, the Joseph and Loretta Lopez Chair Professor of Mathematics at Rutgers University. "However, increased communication among vehicles and increased levels of autonomy in human-driven vehicles is in the near future."

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.