Speed Cameras Shown to Increase Road Efficiency
The study, which became available to the public this summer, looked at a trial photo enforcement program on a segment of Arizona State Loop 101 in Scottsdale. The program — the first in the U.S. to use fixed-site speed cameras on a freeway — ran from January through October 2006 and cited drivers going at least 11 miles over the 65 mph speed limit.
Simon Washington, the Arizona State University engineering professor who co-authored the report, found that the speed camera program “not only improved safety but also improved mobility through travel time savings, improved travel time reliability, and reduced travel time uncertainty.”
The report found that during the nine month speed camera trial program
- mean traffic speeds were reduced by nine mph
- total crashes were reduced by 44% to 54%
- injury crashes decreased by 28% to 48%
The report estimated that the reduction in crash frequency saved approximately 1,336 vehicle-hours a year when crashes blocked one lane and 45,060 vehicle-hours a year when crashes blocked two lanes. The annual benefit of travel time savings ranged from a low of $20,040 (one-lane blockage crash assuming $15/hr value of travel time savings) to a high of $901,200 (two-lane blockage crash assuming $20/hr of travel time savings). The six speed cameras (three facing in each direction of traffic) produced a clear change in driving behavior.
The average number of daily speeding detections per camera was
- 162.2 during the warning period;
- 129.7 during the program period;
- 1,482.4 during the after period; and
- 134.68 during the reactivation period.
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