Ford Self-Driving Car Video Shows in Painful Detail a "Phantom Traffic Jam"

Just in time for the holiday weekend. 

by James Dennin

Some traffic jams have a clear cause: A tire blew, or a collision shut down one of the lanes. There’s not much we can do about that besides clear the road and get people moving again. But there may be something we can do about phantom traffic jams, those strange moments where everyone on the highway grinds to a halt for no apparent reason.

In fact, stopping phantom traffic jams may already be within reach, thanks to existing and commercially available technologies like adaptive cruise control. Researchers working with the National Science Foundation and Ford tell Inverse their work provides a preview of the safer, ever-flowing highways that will some day be enabled by self-driving cars.

“You get these cascading waves of tail lights, and that … takes small mistakes and turns them into bigger ones,” Dan Work, a professor of engineering and computer science at Vanderbilt University who led the Ford study says. “It’s a huge issue for the transportation community, understanding the causes.”

Researchers like Work are interested in whether already commercially available technologies like ACC can already make roads safer. So they carried out a study to determine whether adaptive cruise control can stop these semi-random occurrences by incrementally adjusting everyone’s speeds. In a series of 25 road tests comparing human drivers in a phantom jam with drivers enabling ACC, researchers found that only a third of drivers need to engage ACC for the human causes of phantom jams to disappear.

Can Adaptive Cruise Control End Traffic Jams?

It’s an interesting finding, because the technology needed to study phantom traffic jams has only recently become widely available, Work said (the Ford experiment, for example, used drones.)

“It is a core feature of traffic,” Work said. “But quantifying the impact of [phantom traffic jams] is still at the forefront of the research, and part of the reason is that for the last 30 or 40 years, researchers have not been able to see those waves.”

To conduct its experiment, Ford had 36 drivers recreate highway conditions across three lanes. At one point a head driver then slowed from 60 mph to 40 mph to simulate some sort of non-emergency occurrence. In the all-human group, the tail car slowed all the way to 15 mph. In the all ACC group, the slowest car only reached 53 mph.

AAC is better at reacting to these driving interruptions than humans because they react automatically, Work explained. Perhaps more importantly, most drivers can already use it: Ford says it comes standard in about 70 percent of its vehicles, for example.

So the next time you’re making for a crowded holiday highway, be sure to switch on your automatic cruise control, and there’s a chance everyone will be able to get where they’re going that much faster.

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