Vanderbilt researchers study how to stop ‘phantom’ traffic jams

NASHVILLE, Tenn. (WKRN) — It’s never fun getting stuck in a traffic jam, but what if you can make one single change with your car to prevent backups? 

Vanderbilt University researchers tested exactly that in the middle of rush hour on Interstate 24 and News 2 took a look at what they found and how it can revolutionize your commute. 

We’ve all been there. You slam on the brakes because you’re stuck in a traffic jam, but it’s not really clear what’s causing the slow down. 

“There’s not a wreck. There’s not a lane merge. There’s not a car stuck in the middle of the road trying to change lanes. You’re like, ‘What happened? Why did we slow down?'” said Vanderbilt researcher Jonathan Sprinkle.

Sprinkle has a name for this bizarre traffic jam: “They’re sometimes called ‘phantom’ traffic jams.” 

His team at Vanderbilt is on a mission to stamp these out once and for all, but first, they have to understand how they happen. Turns out, drivers play a crucial role.

“The car in front of you has maybe slowed down, you slow down, you almost always slow down just a little bit more than that car, and the person behind you does the same.”

Click here to see what that looks like in real time. As more and more drivers hit the brake, it causes a ripple effect, essentially a phantom traffic jam, but once researchers take just a single car and flip on the automatic cruise control button to an average traffic speed, the phantom traffic jam suddenly disappears. 

“The idea with one was to say, ‘Can we just drive smoother? Will all the other cars behind us also just drive smoother?’ And it was a revelation result that it worked pretty well.”

The automatic cruise control worked so well with just one car that researchers expanded it, testing on I-24, one of the busiest roads in Tennessee, retrofitting 100 cars with speed and automatic cruise control while cameras track the results. 

At this time, the research is being peer-reviewed, but the goal is to one day make our commutes more fuel-efficient and safer. 

“Making all these really small tweaks that have this tremendous benefit for society,” Sprinkle said.

Vanderbilt is working with several universities on this study, including Rutgers University, the University of Arizona and the University of California, Berkeley.