MANSFIELD, OH --- Here's a question for all you veteran fleet managers: How long are the dashed lines painted down the middle of a road? There's a federal guideline for every street, highway and rural road in the U.S., where dashed lines separate lanes or indicate where drivers can pass. So how long are those lines? Two feet? Three feet?

The answer is 10 feet. If you answered less than that, take comfort in knowing that a new study found that people grossly underestimate the length of these lines -- a fact that suggests most drivers underestimate distances as they drive.

The study appeared in the journal Perception & Psychophysics. The study was led by Dennis Shaffer, assistant professor of psychology at Ohio State University's Mansfield campus.

The study tested 400 college students in three experiments. When asked to estimate the length of the lines, most students guessed two feet.

"This means that to most people, 40 feet looks like a lot less than 40 feet when they're on the road," Shaffer explained to ScienceDaily. "People cover more ground than they think in a given period of time, so they are probably underestimating their speed."