Phantom traffic jams unlocked
27th February, 2018: A new study by researchers of
Massachusetts Institute of Technology (MIT) reveals the causes behind the so
called “phantom traffic jams”, the traffic jams which occurs without any apparent
reason and suggests plausible solutions. The results are published in the
journal IEEE Transactions on Intelligent Transportation Systems.
Phantom traffic jams are known to every driver. The traffic crawls to a halt from high tempo, without any apparent reason, like an accident, a construction site, etc. Professor Berthold Horn of MIT has studied the phenomena for long years before he came to an interesting insight into how to avoid its occurrence.
According to Professor Horn, phantom jam begins as a single car in a dense traffic slows down due to some reason or the other. Even when this is a slight slowdown, the car behind that vehicle is forced to slow even more and this spirals backward into the entire system of traffic as a wave, getting worse the farther it spreads. Eventually, the cars far behind are forced to stop completely to avoid hitting the slower vehicle ahead. The traffic comes to a halt over nothing, causing a “Phantom traffic jam”.
Professor Horn also suggests clues to avoid phantom traffic jams. The first idea is to increase the distances between cars in a stream of traffic. If the distances between the vehicles are sufficiently large, the slow-down effect will not get amplified by the vehicles that follow behind. Each driver will be able to make course corrections to accommodate the slowing down of the vehicle in front, without creating any spiraling effect.
Horn calls this method of vehicle spacing bilateral control. It could be achieved through simple modifications to the adaptive cruise control (ACC), many modern vehicles possess. The networked self-driving cars of the future should invariably incorporate adaptive cruise control to avoid phantom traffic jams, recommends Prof. Horn. Making sure that equal spacing is maintained between vehicles on the road, rather than tailgating, the problem of phantom traffic jams could be completely eliminated, concludes Prof. Horn.