Reported August 2008

TRAFFIC FLOW: Scientists studying traffic's ebb and flow create complex mathematical models in order to simulate the actual patterns that emerge on roads. These models are an important part of efforts to improve the placement or timing of various items like traffic lights, additional lanes and more. The scientists use insights developed from sources as diverse as the physics of fluid flow and human reaction time in order to build better models and glean insights from them.

THE PHYSICS OF TRAFFIC: Conventional scientific wisdom compares traffic jams to the process of freezing, where a flowing liquid turns into a solid. On a sparsely populated highway the cars are far apart and can move at whatever speed they choose while freely moving between lanes -- much like the molecules in a gas. In heavier traffic, the cars are more densely packed with less room to maneuver, so cars move at slower average speeds and traffic behaves more like a liquid. If the cars become too densely packed, their speed is reduced, and their movement restricted, to such an extent that they almost stop moving altogether and form a "solid" expanse of traffic -- "freezing" into ice.

The Human Factors and Ergonomics Society and the Institute for Operations Research and the Management Sciences contributed to the information contained in the TV portion of this report.

If you would like more information, please contact:

Byungkyu (Brian) Park, Assistant Professor
Department of Civil & Environmental Engineering
University of Virginia
Charlottesville, VA 22904-4742
(434) 924-6347
bp6v@Virginia.EDU

Human Factors and Ergonomics Society
Santa Monica, CA 90406
(310) 394-1811
http://www.hfes.org

Institute for Operations Research and the Management Sciences
Barry List
(443) 757-3560
barry.list@informs.org