Before long, traffic went from a smooth flow to a series of stops and starts. “Phantom traffic jams are created by drivers like you and me,” Work explained.

The professor of civil and environmental engineering at Vanderbilt University is one of a group of engineers and mathematicians from universities around the U.S. who have been studying the problem of ...

Then, as traffic clears, the drivers accelerate too quickly, causing more braking and yet another jam. “We know that one car braking suddenly can have a huge impact,” Work said.