Congestion

Unintended Consequences: Booting Hybrids from HOV Lanes Slows Traffic

Submitted by ITSLibrary on Tue, 2011-10-11 15:18
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 Hybrid car in the carpool lane, Institute of Transportation Studies, University of California, Berkeley

This past July, the California Clean Air Stickers for HOV Lanes program ended for hybrids. What was the effect of this change? How did it affect traffic flow and congestion? That question was investigated by ITS researchers Prof. Michael Cassidy and Kitae Jang, of the Volvo Center.  Their new ITS report, Dual Influences on Vehicle Speeds in Special-Use Lanes and Policy Implications, analysed traffic data and used models to calculate the impact of the added low-emissions vehicles on the other lanes. Cassidy told the Berkeley Newscenter:

“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.”

...

“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.”

The paper was also discussed by the New York Times, USA Today, and the LA Times. 

Derailment Raises Issue of Second NY/NJ Transit Tunnel

Submitted by ITSLibrary on Thu, 2011-08-11 14:40
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A Northeast Corridor train derailment disrupted New Jersey Transit service to and from New York earlier this week. The derailment and resulting commuter nightmare has some transit riders calling for officials to reconsider the decision to kill the Mass Transit Tunnel. Groundbreaking for that project, which would have resulted in a second transit tunnel under the Hudson River, was held in 2009, but New Jersey Gov. Chris Christie killed the over-budget project in October of last year. The governor has indicated a willingness to consider other projects to increase transit capacity between New Jersey and New York. An Amtrak derailment earlier today is causing further headaches for NJ Transit.

Screen out rubbernecking?

Submitted by ITSLibrary on Tue, 2011-07-12 15:02
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 Turning it back on its tires by tedkerwin

Today on the Freakonomics Blog, Eric Morris revists the issue of rubbernecking and traffc congestion:

The pinnacle of transportation-related annoyance may be that not only does rubbernecking take place along the route where the accident happens, but it can even cause severe jams in the lanes going the opposite direction. So a few years ago I had what I thought was a bright idea: how about setting up screens at accident sites to hide the scene and prevent gaping?

Finally, somebody is trying out this idea in practice. The Highways Agency in the U.K. has tested such screens. (For more see this, this, this, and this, which leads you to several other links.) The bottom line is that the screens are not perfect; for example, the barriers to which the screens have to be attached vary in size, which creates problems; the screens are vulnerable to wind; the decision about whether to deploy them must be made very rapidly; they have to be able to be set up quickly and safely, etc. Thus they are not suitable for all accident sites. However, as the links above indicate, test results have shown they are effective.

Hopefully there will be more follow up studies on the issue. Will screens be coming stateside soon?

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