|
Videos
October 12, 2011 By News Staff
Transportation researchers affiliated with the University of California, Berkeley, have used roadway sensor data to come to a surprising conclusion: Discontinuing a program that gave solo drivers of hybrid vehicles access to carpool lanes has slowed traffic in all lanes.
Conventional wisdom would lead one to believe that with fewer hybrids in the carpool lane, the traffic in that lane would speed up. But that hasn’t been the case.
Everybody has slowed down — the drivers of hybrid vehicles and all other motorists on the road.
“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," said Michael Cassidy, University of California, Berkeley, professor of civil and environmental engineering, in a news announcement from the university.
Cassidy and a graduate student studied six months’ worth of data from roadway sensors in the San Francisco Bay Area before and after the carpool lane privileges were revoked for hybrid cars. For one stretch of freeway in Hayward, Calif., the researchers concluded that carpool lane speeds were 15 percent slower after hybrids were expelled.
Why?
One, the researchers found that when hybrids moved back into the regular traffic lanes, those lanes were slower — and that contributed to a slowdown in the adjacent carpool lane.
"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 Kitae Jang, the doctoral student who contributed to the research. "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."
Two, in Cassidy’s words, “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. Carpoolers may slow down for fear that a regular-lane car might suddenly enter their lane.”
The researchers said that in order to improve traffic flow, more vehicles — not fewer — should be allowed into carpool lanes.
The researchers presented their results in a report published by UC-Berkeley’s Institute of Transportation Studies. The researchers’ paper is available here.
According to the university, in 2005 California began giving low-emission vehicles, including hybrids, a yellow sticker that qualified them to drive legally in the carpool lane. An estimated 85,000 hybrids in the state had the passes. The program was discontinued July 1 in order to comply with a federal regulation that, according to the Institute of Transportation Studies, requires low-emitting vehicles “be expelled from a carpool lane when traffic slows to below 45 mph on any portion of that lane during more than 10 percent of its operating time.”
You may use or reference this story with attribution and a link to
http://www.govtech.com/transportation/Kicking-Hybrids-from-Carpool-Lanes-Slows-Traffic.html
Collaborative Justice: Transforming Criminal Justice Services Through Unified Collaboration
Cloud-Based Services Accelerate Public Sector Adoption of Video Collaboration
What kind of nonsense is this? The point of carpool lanes isn't just to be faster, but to encourage more drivers to carpool and remove more traffic from the road. The fact that the unintentional impact of moving the same low-occupany cars from one lane to other already-congrested affects the same carpool lanes that have to merge through that traffic isn't correlation. Encouraging drivers of hybrid cars to continue to drive alone, and then have the number of cars on the road be hybrids will still mean traffic is worse, but spread SLIGHTLY across one more lane. The goal MUST stay the same, which is to get single-occupancy vehicles to be less of a proportion of total traffic because THAT is what reduces congestion...not "hybridism".
Well said Lem.
Those are valid points, but for me the larger question is posed by the federal regulation cited in the last paragraph. We should be asking ourselves about the extent of federal micro-management of state and local affairs - honestly, why are the feds interested in what is primarily a local traffic control issue? Perhaps federal funds paid a part of the cost of that stretch of road, but what vital national interest is served by that degree of top-down control?
This is an example of misleading interpretation of results. The study finds that fewer cars in the carpool lanes result in overall slower traffic in all lanes. This has nothing to do with hybrid cars other than the fact that they happened to be the vehicles that were moved into other lanes. The takeaway here is not that HYBRIDS be allowed back into the carpool lanes, it's that if we want traffic to be faster in all lanes, we could let more cars into the carpool lanes--not necessarily hybrids.
the natural extension is that the carpool lanes should be open to all traffic for the best use of the common facility, social engineering versus reality.
Yes, I agree. Every day, I see cars with only a driver whiz past me in the car pool lane. It's almost impossible to enforce. Without enforcement, there is little motivation for scofflaws to follow the rules. Don't pass legislation if there is no enforcement--it really isn't fair to the rest of the people.
A lot of states are adopting laws that will give incentives to people who carpool, one of those incentives being the use of these great carpool lanes. In the case that you think you don't have anyone to carpool with, you might want to try finding people through commuter/carpool websites, which there are plenty of. I've tried Craigslist and eRideshare, but one of my favorites is Amovens.com. It's easy to post rides or find commutes. They even host holiday give-aways, such as a free $25 gas card for people who successfully set-up a carpool for the week of Thanksgiving. I would definitely recommend giving any of the above sites a try!