Drive in Iowa and you'll experience it. Traffic moving along and then... brake lights. You look for a cause - but see nothing. Then, as fast as you stopped, you're moving again.
Daniel McGeehee, director of the National Advanced Driving Simulator and the Transportation and Vehicle Safety Policy Research Program at the University of Iowa, says there's a simple explanation for what's called a phantom traffic jam.
Read and view the full story on KCRG here.