Drivers slowed down an average of 7 mph in Scottsdale, Ariz., six weeks after the city launched its nine-month pilot photo-enforcement program in 2006, according to a new study.
The study also showed that during the same time span, drivers slowed an average of 5 mph on a freeway in Glendale, Ariz., some 25 miles away.
“We were surprised to see speeds decline so far away from the pilot enforcement area,” said Richard Retting, senior transportation engineer at the Insurance Institute for Highway Safety. “Drivers seem to have associated Loop 101 with speed cameras, not just certain stretches of the freeway.”
Researchers attributed the spillover effect in Glendale to massive media attention to the pilot program and to changes in drivers’ behavior.
However, the effect lessened slightly over time.
Eight months after Scottsdale’s program started, the study found that drivers had slowed down an average of 6 mph in Scottsdale and 2 mph in Glendale.
After the test period ended, drivers were slowing an average of 1 mph through Scottsdale but speeding an additional 1 mph in Glendale.
The study was conducted by the Arlington, Va.-based Insurance Institute for Highway Safety, a research and communications organization financed by auto insurers.