High occupancy vehicle (HOV) lanes were created to encourage more environmentally friendly travel. The idea was that if you car pool (carry one or more passengers) with you, then you can have access to a special lane to escape traffic congestion. In some places, people driving green cars (hybrids or electric vehicles (EVs)) could travel in the HOV lane even without passengers. Lately, HOV rules have changed slowing things down.
According to Science Daily researchers at the University of California, Berkeley, studied the impact in California of kicking hybrids with fewer than two occupants out of the HOV lane. Back in 2005, the state allowed drivers of hybrid vehicles to drive in the HOV lane as a perk for driving an environmentally friendly car. That perk ended this year on July 1st. The results were not as expected.
California decided to eliminate the privilege because of critics complaints that hybrids with only one occupant were clogging up the HOV lane. Since the number of hybrids being driven in California had reached 85,000, the state decided to heed the critics.
What resulted according to studies by UC Berkeley’s Institute of Transportation Studies (ITS) is that rather than helping the situation, kicking solo driver hybrids out of the HOV lane only slowed down everyone. Surely this was not the intended effect.
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” in its analysis. Rather than speeding up the HOV lane, all the lanes slowed down. The critics who expected a speedier HOV lane actually got just the opposite.
Two factors account for the poor results in the HOV lane.
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.
EVs, Low Emission Vehicles, or ILEVs, such as hydrogen fuel cell, and natural gas powered cars can still drive in the HOV lane with only one occupant. If the feds allow it “40,000 super-clean plug-in-hybrids or hydrogen-powered internal combustion engine vehicles” will be allowed in the HOV lane even with just a solo driver.
Even with those 40,000 extra cars the ITS is saying that the 85,000 hybrids that lost their HOV solo driver privilege should be allowed back in. According to the study, this would actually speed up the HOV lane by reducing congestion in nearby lanes.
On a non-scientific note, Atlanta has taken its HOV lanes and turned them into toll lanes. You can enter the lanes with a Peachtree Pass and be charged for the distance you drive in the lane. Supposedly this is to speed up traffic and raise revenue at the same time.
While driving into Atlanta recently, I observed a total of six cars in the Peachtree Pass lane from it’s beginning in to downtown. Normally, the lane would have had dozens of cars with multiple passengers speeding right along.
While those willing to pay for the privilege of using the lane might have gotten there faster, the congestion and higher risk of accidents on the rest of the expressway are probably raising first responder costs. By turning the HOV lane into the Peachtree Pass toll lane, the government is probably losing more money than it is gaining in revenues.
Governments need to rethink their elimination or restriction of HOV lanes. The results of those decisions are not turning out as planned.