The only thing worse than hybrid cars in carpool lanes is having them out

Posted By News On October 11, 2011 - 5:00pm

Car pool lanes should not exist. They never worked as intended and having 33% or 25% of highways blocked off for 7% of people has led to higher emissions and more accidents. Some governments, like California, issued a mandate and subsidy for automobile companies and certain owners by also letting hybrid cars use car pool lanes, which also did not help. Now, the end of the ridiculous law is going to slow down traffic even more, according to transportation engineers at the University of California, Berkeley.

The program, which began in 2005 and ended on July 1, gave wealthy consumers an extra incentive to buy low-emission cars and 85,000 low-emission vehicles got yellow stickers that gave them entry into the carpool lanes. Carpoolers objected, since now there were a few more cars and they were driven by solo drivers, and the legislature agreed. Now hybrid cars are slowing everyone down, not just people in the car pool lanes.

Researchers at UC Berkeley's Institute of Transportation Studies (ITS) used traffic flow theories and six months of data from roadway sensors measuring speed and congestion along all freeway carpool lanes in the San Francisco Bay Area. They used the information to predict the impact on vehicle speed of the hybrids' removal from carpool lanes. Additional data collected after the program's July 1 expiration supported their predictions.

Michael Cassidy, UC Berkeley professor of civil and environmental engineering, and Kitae Jang, a doctoral student in civil and environmental engineering, presented their analysis in a new report released by ITS.

"Our results show that everybody is worse off with the program's ending," said Cassidy. "Drivers of low-emission vehicles are worse off, drivers in the regular lanes are worse off, and drivers in the carpool lanes are worse off. Nobody wins."

A carpool lane along a four-mile stretch of I-880 in Hayward, for instance, saw a 15 percent reduction in speed after single-occupant hybrids were expelled after July 1.

The counterintuitive results reflect dual – and opposing – influences on traffic speed in the carpool lanes, the researchers explained. One factor is the presence of additional cars, including hybrids, which slow down traffic. One might think that moving vehicles out would allow the remaining cars in the lane to go faster.

But the data show that traffic speed in the carpool lane is also influenced by the speed of the adjacent lanes. Moving the hybrids into the neighboring lanes increases congestion in those lanes, which in turn slows down the carpoolers.

"As vehicles move out of the carpool lane and into a regular lane, they have to slow down to match the speed of the congested lane," explained Jang. "Likewise, as cars from a slow-moving regular lane try to slip into a carpool lane, they can take time to pick up speed, which also slows down the carpool lane vehicles."

Human nature likely plays a role, too, the researchers said. "Drivers probably feel nervous going 70 miles per hour next to lanes where traffic is stopped or crawling along at 10 or 20 miles per hour," said Cassidy. "Carpoolers may slow down for fear that a regular-lane car might suddenly enter their lane."

Currently, the only single-occupancy vehicles allowed in California's carpool lanes are federally approved Inherently Low Emission Vehicles, or ILEVs, such as hydrogen fuel cell, 100 percent battery electric, and compressed natural gas vehicles with white clean air vehicle stickers. According to the California Air Resources Board, only 14,000 vehicles in the state have qualified thus far.

A new program, pending federal approval next January, will allow 40,000 super-clean plug-in-hybrids or hydrogen-powered internal combustion engine vehicles to claim green clean air vehicle stickers and enter carpool lanes.

But the researchers predict that this will not be enough. They argue that freeway traffic conditions will improve for everyone by increasing, not decreasing, the numbers allowed access to carpool lanes.

Here's a bold idea, since more vehicles in car pool lanes would decrease traffic overall. Get rid of car pool lanes. They don't work and never did.

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