Newswise — It’s happened to us all: driving along when suddenly, traffic comes to an almost complete stop. We crawl along thinking there must be an accident or a broken-down vehicle ahead, but just as suddenly as we slowed, traffic begins moving normally again with no accident or distressed auto in site.
Congratulations, you have just been part of a phantom traffic jam or “jamiton” as it is called by Temple University mathematician Benjamin Seibold. “Whenever there is heavy traffic volume, such as during a holiday weekend like Labor Day, there is the chance of phantom traffic jams,” said Seibold, assistant professor of mathematics, who has been studying this phenomenon for several years. “Heavy traffic is much worse than light traffic, not just because there are more cars around you and traffic moves slower; there is also the danger of stop-and-go waves occurring: instead of a slow but steady traffic flow, you are forced to hit the brake and accelerate your vehicle constantly.”
Much like a detonation wave from an explosion, a “jamiton” can ripple through the moving traffic, causing delays at numerous points quite a distance back from the origin of the initial traffic slow down.
Seibold and his colleagues are currently studying what an individual driver can do to prevent phantom traffic jams. Their research has revealed the following two hints, which are intuitive, but may in fact require a change in driving behavior for many drivers:* Avoid peaks in traffic density: “When there is a big lump of carsahead of you, slow down early and thus delay your running into it.”* Create a safety distance: “Increasing your distance to the carahead by a little bit allows you to decelerate more smoothly and thusto reduce the impact of these traffic waves.”
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