California's Carpool Lane Welcomes Another Car

Future Chevy Volt owners in California may be excited to learn that, starting with the 2012 model of the hybrid car, they'll be able to take advantage of the Golden State’s 1,400 miles of carpool lanes (a.k.a. high- occupancy vehicle [a.k.a HOV]) lanes.

That’s assuming drivers have opted for the low-emissions package and don’t wait too long: The state issues just 40,000 HOV stickers for low-polluting vehicles, so not every qualified car owner is guaranteed a spot in the fast lane.

Once upon a time, you had to be a carpool (that is, have at least two people per vehicle) to drive in California's exclusive lanes. But several years ago, to promote hybrids, electric cars, and other low-emission vehicles, the state changed the law to give these cars HOV status, regardless of how many people are on board.

But in a controversial decision, perhaps bowing to pressure from actual carpoolers who felt the additional 85,000 cars in their lane were causing congestion, on July 1, 2011, state officials pulled the plug on the program, which started in 2005, that allowed single-occupant hybrid vehicles access to carpool lanes in California. The Chevy Volt has apparently been exempted because it runs on battery power, with zero tailpipe emissions, for the first 35 miles.

With 85,000 fewer cars, traffic in the carpool lane should be much smoother now, right? Wrong.

The original idea behind carpool lanes was to improve traffic flow and to reduce the number of cars on the road. Well, Michael Cassidy, an engineering professor at UC Berkeley and the co-author of a recent study about carpool lanes and traffic in the San Francisco Bay Area, believes that more, not fewer, vehicles should be exempt from the laws governing access to the carpool lane.

“That would be better for everyone,” Cassidy says. That includes drivers in the carpool lanes as well as the regular lanes. But as things currently stand, “everyone is worse off,” he says.

Cassidy’s research shows that traffic congestion in the carpool lane is not a result of too many cars, but rather of external factors. He found that flow in carpool lanes is strongly influenced by the speed of traffic in the non-VIP lanes next to them. His study also suggested that when drivers move in and out of the carpool lane, both lanes get slowed. Which makes the environment suffers as well, since now “everyone spends more time on the road.”

--Josh Marx / image courtesy Chevrolet