Reported January 2007

BACKGROUND: Smart cars and smart roads are the wave of the future, as the U.S. Federal Highway Administration has begun to explore vehicle-to-roadside and vehicle-to-vehicle communication using wireless transmission.

HOW IT WORKS: As part of California's Vehicle Infrastructure Integration Initiative, a transmitter embedded in the road would beam wireless signals, which would in turn be detected by the receiver in the "smart car." An alert would be displayed on a monitor in the car if there were an accident or icy road ahead, or if it were unsafe to enter an intersection. Vehicles could serve both as data collectors and also anonymously transmit traffic and road condition information from every major road within the transportation networks. Also, car manufacturers could more quickly notify drivers of warranty or recall needs.

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.

WHAT ARE MEMS? Microelectro-mechanical systems (MEMs) integrate electronic and moving parts onto a microscopic silicon chip, making them ideal for new sensor technology. The term MEMS was coined in the 1980s. A MEMS device is usually only a few micrometers wide; for comparison, a human hair is 50 micrometers wide. Among other everyday applications, MEMS-based sensors are used in cars to detect the sudden motion of a collision and trigger release of the airbag. They are also found in ink-jet printers, blood pressure monitors, and projection display systems.

The Human Factors and Ergonomics Society contributed to the information contained in the TV portion of this report.

If you would like more information, please contact:

James Misener
Transportation Engineer
University of California, Berkeley
(510) 665-3612
misener@path.berkeley.edu

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

FACTOIDS...

The average U.S. motorist spends 36 hours every year caught in traffic delays. It costs an individual driver living in a large city an estimated $1,000 every year in wasted fuel and productivity.

State and federal agencies spend about $750 million each year on traffic monitoring.

ON THE WEB...

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