CONTACTTRAFFICABOUT TOM VANDERBILTOTHER WRITING CONTACT ABOUT THE BOOK

Archive for March 10th, 2009

What’s the Effect of Rubbernecking on Traffic Flow?

We all intuitively know that a crash — or even a disabled vehicle or a piece of interesting debris on the roadside — can disrupt the flow of traffic. Cambridge Systematics has suggested that as much as 25% of congestion in the U.S. is due to “incidents.” Some of this due to physical loss of highway capacity (e.g., a blocked lane). But how much is actually due to drivers slowing down to rubberneck? (the dreaded “gaper’s block,” as they say in the Midwest)

Previous estimates have been based largely on models or “macroscopic” calculations. But an interesting bit of research — one version is here — by a Dutch team (Victor Knoop, Serge Hoogendoorn, and Henk J. van Zuylen, at the Delft University of Technology), to be published as part of this conference, has examined the “microscopic behavior” of drivers at crash sites, as well as quantified the actual loss in traffic capacity due to rubbernecking.

How did they do it? The authors write: “The observation team waited at the Traffic Management Center in the centre of the Netherlands until an accident had occurred somewhere nearby, after which it flew with the helicopter to the accident location. From the moment of arrival, traffic operations for both directions were recorded. From the other side of the road, the incident was visible but there was no physical obstruction.” They point out, by the way, that the helicopter was high enough to itself not be a cause of traffic disruption.

As pictured above, a light truck overturned near the city of Apeldoorn. One lane (in the ‘bottom section’ in the photo above) was closed for the sake of emergency response. Not surprisingly, given that a lane was missing, and two lanes had to merge, the researchers a large drop in “outflow capacity” in the section closest to the overturned van.

But what is striking is the airborne researchers observed a sizable effect — roughly a 50% capacity reduction — in the opposite bit of highway, in which no lanes were blocked. The video of this is rather amazing: At roughly the position that affords the best view of the crash, the traffic begins to bunch, as it does in stop-and-go congestion, even though the road ahead is otherwise clear. One vehicle, the “leader” is essentially slowing to look at the incident, creating in essence a backward “shock wave” that everyone else drives into. Once in the slowing wave, their curiosity is no doubt aroused and so they too continue to creep along for a look. At the exact point of the wreck, the traffic again begins to accelerate.

This raises the idea of the magical “first driver” in a traffic jam you may have wondered about as a child — the idea that there must be some driver at the head of even the longest traffic jam, and if only they would get going, or hadn’t slowed to begin with, things wouldn’t be so bad for us, etc. It also raises Thomas Schelling’s description of rubbernecking in the classic book Micromotives and Macrobehavior: Because they’ve already been made to wait because of everyone else’s look, each individual driver feels they too have the right to look themselves. Each person’s five seconds adds up to incremental delays (“it is a bad bargain,” he wrote). If everyone could only agree not to look, the congestion actually would not form.

There were a number of other interesting observations made. On the section of highway without any physical obstruction, the speed of vehicles in the left lane drops faster than those in the right (the authors speculate that left-lane cars are probably going faster to begin with; that they may be closer to the event and thus more distracted; and that there are more slower-moving trucks in the right lane).

Another curious phenomenon is that as the lead vehicle accelerates past the point of the crash, the time that the following driver begins to also accelerate varies more widely than under the “normal” conditions of heavy congestion. It is as if some drivers are simply more distracted by the sight of the crash, or perhaps some drivers instinctively behave with more caution in the immediate aftermath (the presence of emergency personnel may also affect driver behavior). All drivers react more slowly than in typical conditions, but some react much more slowly.

In any case, this is fascinating research that suggests the traffic impacts of rubbenecking are greater than those found in previous work.

Posted on Tuesday, March 10th, 2009 at 4:18 pm by: Tom Vanderbilt
Comments Off on What’s the Effect of Rubbernecking on Traffic Flow?. Click here to leave a comment.
Traffic Tom Vanderbilt

How We Drive is the companion blog to Tom Vanderbilt’s New York Times bestselling book, Traffic: Why We Drive the Way We Do (and What It Says About Us), published by Alfred A. Knopf in the U.S. and Canada, Penguin in the U.K, and in languages other than English by a number of other fine publishers worldwide.

Please send tips, news, research papers, links, photos (bad road signs, outrageous bumper stickers, spectacularly awful acts of driving or parking or anything traffic-related), or ideas for my Slate.com Transport column to me at: info@howwedrive.com.

For publicity inquiries, please contact Kate Runde at Vintage: krunde@randomhouse.com.

For editorial inquiries, please contact Zoe Pagnamenta at The Zoe Pagnamenta Agency: zoe@zpagency.com.

For speaking engagement inquiries, please contact
Kim Thornton at the Random House Speakers Bureau: rhspeakers@randomhouse.com.

Order Traffic from:

Amazon | B&N | Borders
Random House | Powell’s

U.S. Paperback UK Paperback
Traffic UK
Drive-on-the-left types can order the book from Amazon.co.uk.

For UK publicity enquiries please contact Rosie Glaisher at Penguin.

Upcoming Talks

April 9, 2008.
California Office of Traffic Safety Summit
San Francisco, CA.

May 19, 2009
University of Minnesota Center for Transportation Studies
Bloomington, MN

June 23, 2009
Driving Assessment 2009
Big Sky, Montana

June 26, 2009
PRI World Congress
Rotterdam, The Netherlands

June 27, 2009
Day of Architecture
Utrecht, The Netherlands

July 13, 2009
Association of Transportation Safety Information Professionals (ATSIP)
Phoenix, AZ.

August 12-14
Texas Department of Transportation “Save a Life Summit”
San Antonio, Texas

September 2, 2009
Governors Highway Safety Association Annual Meeting
Savannah, Georgia

September 11, 2009
Oregon Transportation Summit
Portland, Oregon

October 8
Honda R&D Americas
Raymond, Ohio

October 10-11
INFORMS Roundtable
San Diego, CA

October 21, 2009
California State University-San Bernardino, Leonard Transportation Center
San Bernardino, CA

November 5
Southern New England Planning Association Planning Conference
Uncasville, Connecticut

January 6
Texas Transportation Forum
Austin, TX

January 19
Yale University
(with Donald Shoup; details to come)

Monday, February 22
Yale University School of Architecture
Eero Saarinen Lecture

Friday, March 19
University of Delaware
Delaware Center for Transportation

April 5-7
University of Utah
Salt Lake City
McMurrin Lectureship

April 19
International Bridge, Tunnel and Turnpike Association (Organization Management Workshop)
Austin, Texas

Monday, April 26
Edmonton Traffic Safety Conference
Edmonton, Canada

Monday, June 7
Canadian Association of Road Safety Professionals
Niagara Falls, Ontario

Wednesday, July 6
Fondo de Prevención Vial
Bogotá, Colombia

Tuesday, August 31
Royal Automobile Club
Perth, Australia

Wednesday, September 1
Australasian Road Safety Conference
Canberra, Australia

Wednesday, September 22

Wisconsin Department of Transportation’s
Traffic Incident Management Enhancement Program
Statewide Conference
Wisconsin Dells, WI

Wednesday, October 20
Rutgers University
Center for Advanced Infrastructure and Transportation
Piscataway, NJ

Tuesday, March 8, 2011
Ontario Injury Prevention Resource Centre
Injury Prevention Forum
Toronto

Monday, May 2
Idaho Public Driver Education Conference
Boise, Idaho

Tuesday, June 2, 2011
California Association of Cities
Costa Mesa, California

Sunday, August 21, 2011
American Association of Motor Vehicle Administrators
Milwaukee, Wisconsin

Wednesday, October 26, 2011
Attitudes: Iniciativa Social de Audi
Madrid, Spain

April 16, 2012
Institute for Sensible Transport Seminar
Gardens Theatre, QUT
Brisbane, Australia

April 17, 2012
Institute for Sensible Transport Seminar
Centennial Plaza, Sydney
Sydney, Australia

April 19, 2012
Institute for Sensible Transport Seminar
Melbourne Town Hall
Melbourne, Australia

January 30, 2013
University of Minnesota City Engineers Association Meeting
Minneapolis, MN

January 31, 2013
Metropolis and Mobile Life
School of Architecture, University of Toronto

February 22, 2013
ISL Engineering
Edmonton, Canada

March 1, 2013
Australian Road Summit
Melbourne, Australia

May 8, 2013
New York State Association of
Transportation Engineers
Rochester, NY

August 18, 2013
BoingBoing.com “Ingenuity” Conference
San Francisco, CA

September 26, 2013
TransComm 2013
(Meeting of American Association
of State Highway and Transportation
Officials’ Subcommittee on Transportation
Communications.
Grand Rapids MI

 

 

Twitter
March 2009
M T W T F S S
« Feb   Apr »
 1
2345678
9101112131415
16171819202122
23242526272829
3031  

No, http://www.knixie.net/ you probably http://www.keilpumps.net/ won be compensated one million dollars; however, with the right http://www.thebootpub.com/ blend http://www.trollophut.com/ of negotiating skills and patience, your efforts will be http://www.thrivingin2010.com/ substantially rewarded!I have seen up to forty http://www.keetraining.com thousand http://www.openairblog.com dollars added to starting compensation through diligent http://www.eopic.com negotiations. It is a way to http://www.waafia.com significantly raise your standard of living http://www.stanleybarker.com and sense of self, simply by