Does Changing Lanes Get You There Faster?


Feb. 15, 2005 -- -- It's a question virtually every driver has asked themselves at some point in a traffic jam: "Is the lane next to me moving faster?" According to a study by two University of Toronto researchers, the answer is no.

In fact, according to their research, not only will weaving back and forth between lanes not get you to your destination faster, it could put you and your passengers' lives at risk.

Changing lanes "gets you there in about the same time, but lane changes on the highway especially can cause car accidents," said Dr. Robert Tibshirani in a telephone interview. "So the ultimate conclusion is that it's not any faster and it's dangerous."

Tibshirani and Dr. Donald Redelmeier, co-author of the 1999 study, used computers to simulate two lanes of stop-and-go highway traffic that were traveling at the same overall average speed.

"The simulation showed that if you looked over to the other lane," Tibshirani explained, "you would see more cars passing your eyes than you expect to see. It's sort of an illusion -- the other lane looks faster when in fact it's not."

Part of the illusion is created by the fact that if you're stuck in traffic and not moving, you're watching cars pull away from you as you sit still.

"You're in the driver's seat, you're looking over at a random time and if you happen to see a car that goes by you, you assume that the lane is going faster," said Tibshirani. "But the point is you're more likely to see a car if the [other] lane is going faster, so again, it's an illusion."

Tibshirani says our own perception -- made up of a variety of factors -- makes us see things that may not really be there.

"The only way to really know how fast the lanes are moving is to stand on the side of the road," he said.

Aside from the time you're losing when making unnecessary lane changes, the study lists several ways you're also putting your passengers and other drivers at risk.

For one, while you're in the act of changing lanes, you're vulnerable to two lanes of traffic at once.

Second, it complicates an already complicated activity by forcing the driver to judge how much room they have for the maneuver.

Third, every car has a blind spot, and when you're moving from one lane to another, it's harder for you to keep an eye on drivers who might be coming up on your car's blind spot.

Another thing to remember when changing lanes is that when you hit your brakes, so does everyone behind you. Lane changes alter the flow of traffic for the other cars and means that they have to make adjustments too.

Despite the study's findings, Tibshirani says that there are times when changing lanes is the right move.

"Sometimes the other lane is obviously going faster," said Tibshirani, "but it's not as often as you might think. Just remember: if you do change lanes, to do it with caution."

As for himself, Tibshirani doesn't have to worry too often about the inherent dangers of lane-changing -- he mostly rides his bicycle around campus.

But when he is in his car, you might think he'd pick a lane and stick to it.

"Of course I change lanes," he said, laughing. "I just try not to do it as often as I did before I knew this."

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