They're designed to ease congestion, encourage carpooling and help the environment. But a new study shows High Occupancy Vehicle, or HOV, lanes may also dramatically increase the danger of freeway driving.
The Texas Transportation Institute analyzed crash data from Dallas HOV lanes. Their findings?
"We found that the crashes did increase significantly," says Scott Cooner with the Texas Transportation Institute.
Specifically, the study found a 41 to 56 percent increase in the rate of injury crashes after carpool lanes were added to existing freeways. An earlier study in California found at least an 11 percent increase in crashes.
"You've often got a 30 mile-an-hour difference in speed, which is an issue for crash involvement," says Cooner.
The most common accidents are rear end collisions, as slower-moving cars try to merge with fast-moving HOV lanes. Or, when drivers are forced to slow dramatically to exit an HOV lane, and merge with bumper-to-bumper traffic.
And yet another danger: Drivers using HOV lanes as passing lanes, illegally weaving in and out to get around slower moving traffic.
In Dallas, Bradley Boswell was injured in a five-car pile-up last summer when a truck swerved into the carpool lane in front of him.
"I'm really weary of the trucks, that's for sure," says Boswell. "There's not much, there's no barrier there, you know."
In fact, according to the Texas study, carpool lanes with barriers showed no increase in accidents.
Researchers recommend widening the lanes where possible and adding barriers to the nation's 2,500 miles of existing HOV lanes. The cost? An additional $116,000 per mile.
Still, Texas transportation officials are planning changes.
"Every one of the rebuilt projects will have barrier-separated HOV lanes where they're now paint striped," says Andy Oberlander with the Texas Department of Transportation. "We do not plan to implement any more paint-striped HOVs in the Dallas district."
In the meantime, drivers beware, when the only thing separating 55 m.p.h. carpools from gridlock is a painted line.