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A New Approach to Traffic Control: Ears on the Ground

Santander, Spain, tested a network of acoustic sensors capable of managing traffic congestion. But will it stand up to the future of cars?
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Ear-It

Los Angeles traffic and law enforcement tried, and failed, to stop the Olympic cyclists from racing on the freeway. And so on Sunday, August 5, 1984, a 17-mile stretch of southern California's Route 91 was closed to traffic for 16 hours as long-distance bikers pedaled for the gold.

It was just one of many traffic-related headaches the '84 games caused L.A. Yet the anticipation of Olympic congestion also inspired the city's famed Automated Traffic Surveillance and Control (ATSAC), a system of just-below-pavement electromagnetic coils that pick up on passing cars and transmit traffic data to a central computer, which enhances "green-time" to ease backups. The system proved so effective in stadium-adjacent tests that it's since expanded to some 4,400 intersections around the city. It also inspired many U.S. metros  (Buffalo, Pittsburgh, Portland, and Atlanta, to name a few) to develop similar congestion-control systems based on magnetic induction, video data, radar, or even car Bluetooth signals.