The Science Of Traffic

How do engineers explain mysteries such as phantom traffic jams and why a brief drop in volume can trigger a traffic jam?

1 minute read

July 1, 2005, 9:00 AM PDT

By Chris Steins @planetizen

" 'Weaving is the worst condition for traffic flow,' says Prof. Polus. Because drivers in heavy traffic brake when a car pulls into their lane, and because it takes time to get back up to speed, there are larger and constantly-changing gaps between vehicles. That invites yet more cars to change lanes, propagating a wave of stop-and-go traffic that cuts the number of cars in a stretch of road by about 10%, calculates Prof. Polus, who will present his work at the 16th International Symposium on Transportation and Traffic Theory at the University of Maryland this month. That may not sound so dire, but in rush hour the result is a five-mile backup, his calculations show. In congestion, be content with the lane you're in."

[Editor's note: The link below is available for a period of 7 days.]

Thanks to Chris Steins

FULL STORY: How Brief Drop in Cars Can Trigger Tie-Ups, And Other Traffic Tales

Friday, July 1, 2005 in Wall St. Journal

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