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Good Question: Does Changing Lanes Save You Time?

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By Jason DeRusha, WCCO-TV

MINNEAPOLIS (WCCO) – There are two kinds of drivers: those who pick a lane and stay in it, and those who obsessively change lanes, looking for an advantage.

But does changing lanes during rush hour really save you time?

“There’s some fairly complicated mathematics involved for proving this,” said Dr. Bryan Dawson, chair of the math department at Union University in Tennessee.

He wrote a study on Highway Relativity, looking into whether we accurately perceive the speed of the lanes of traffic around us.

“If you’re in heavy traffic, it’s really hard for an individual to really determine which lane is faster,” he said.

Researchers call it “lane envy.” It’s the feeling we have when we look to our left and see cars zipping past us.
Psychologists talk about the “highway illusion” where people think they’re moving slower than other traffic, partially because when we’re moving slowly and being passed, we have more time to look from side to side. That’s easier to observe than the vehicles we pass and leave in the dust.

University of Minnesota civil engineering professor Gary Davis suggested that if we are taking a drive that normally takes 10 minutes at 60 miles per hour, and then end up on that same drive going 50mph, we perceive that as a longer delay than it really is.

“Now it takes me 12 minutes to make the trip, for a delay of 2 minutes. This is less time than I spent picking out my shoes and socks this morning. But if I want to go 60 and I’m forced to go 50 I can feel like I’m being delayed for the entire 12 minutes,” he said.

The math professor found a similar psychological effect: “If you’re traveling slower than the average, the effect is magnified, it seems the average speed of other drivers is larger than it really is,” he said.

Because we only observe what’s out our window, we tend to extrapolate that to have some meaning about the average speed for an entire trip. The reality is, all lanes tend to average out to be moving at approximately the same speed.

This matters, because around 3 percent of all fatal crashes in the U.S. involve changing lanes or merging. That’s thousands of deaths. Many of which could presumably be prevented, if people weren’t making unnecessary lane changes.

“Sometimes you change lanes and you wish you hadn’t. I’ve been there many times,” Dawson said.

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