Road Test Shows Some Adaptive Cruise Control Systems Can Amplify Phantom Jams: Taking Driver-Assist Technology Past Comfort and into Traffic Relief
To better understand how ACC systems effect congestion researchers "tested seven different cars from two manufacturers on a remote, rural roadway in Arizona. They simulated various driving conditions with a pace car changing its speed, followed by a vehicle[s] using adaptive cruise control." They then used these results to calibrate various mathematical models designed to measure the overall impact of ACC systems on congestion.
Open-road tests show that adaptive cruise control systems can amplify breaking behaviors, potentially causing "phantom jams."
- After the initial car slowed down each car following it showed a "progressively more extreme braking response"
- ACC system amplified initial disturbances by as much as six times
- Manufacturers of these systems should consider traffic impacts when designing ACC systems along with safety.
See also: Gunter, George, et al, "Are Commercially Implemented Adaptive Cruise Control Systems String Stable?," ArXiv, May 2019.