The Arizona Department of Public Safety first began its photo enforcement program in November 2006, prior to the Arizona Legislature and governor enacting legislation calling for the current expanded program.
At the time, DPS supported the program using alternate funding because of its potential to save lives on Arizona highways.
Establishment of the program followed a nine-month pilot project in Scottsdale and detailed analysis in which Dr. Simon Washington of Arizona State University determined photo enforcement was effective at reducing the number and severity of collisions on state highways, with an overall reduction of 54 percent during non-peak driving hours.
Washington also noted improved driving times and reduced costs related to emergency services as a result of the pilot project. Washington’s study is available at http://www.azdot.gov/TPD/ATRC/publications/project_reports/PDF/AZ684.pdf.
ALREADY SAVING LIVES
Some criticism has occurred over preliminary statistics released for the first 80 days of the expanded photo enforcement program. While the statistics do not represent a comprehensive study such as Washington’s, DPS did not refer to the statistics as a study.
The preliminary statistics were released as raw data. A simple analysis was conducted comparing the results to collision statistics for the same period in 2007. When accounting for a downward trend in fatal collisions over the last several years, the period still showed a reduction in fatal collisions of 30 percent.
Other factors such as fuel prices and economic conditions may have influenced driving behavior during the period, however a reduction as significant as 30 percent suggests photo enforcement is effective, especially in light of Washington’s findings. DPS is only funded for a portion of the costs incurred in administering the photo enforcement program and would welcome a portion of the program revenues being earmarked for additional study.
ESTABLISHING A STEADY SPEED
The original proposal for the expanded program was based upon stationary speed systems only. DPS has elected to use a variety of systems because of improved safety. Although DPS was originally tasked with deploying 100 systems statewide by the end of January, we will continue to evaluate the program on an ongoing basis to ensure it is improving the safety of Arizona highways.
There are currently 76 systems operating, including 34 stationary cameras in the Phoenix area. Further expansion will depend on analysis of collision rates.
Stationary system locations are determined using serious injury and fatal collision statistics for non-peak traffic hours.
This is because serious collisions occur primarily at high speeds which generally don’t occur during rush-hour congestion.
The program’s effectiveness at reducing serious collisions is further improved by placing the systems in corridors approaching major junction areas. Placing the systems closer together prevents drivers from speeding up and then slowing down at each system in the series within the corridor. Reduced speeds, shorter stopping distances, and more consistent speeds produced by photo enforcement all contribute to safer movement of traffic in these areas.
Although concerns have been expressed about increased collisions caused by motorists braking suddenly when encountering the stationary systems, Washington’s study did not find a statistically valid increase in rear-end collisions despite the fact the pilot project did not include the warning signs now in place prior to all deployments on state highways.
Results of the DPS programs have been consistent with Washington’s findings.
Mobile systems have the advantage of increasing safety over larger areas because they are not restricted to a permanent location. They can also be deployed in response to changes in collision rates caused by factors such as construction zones.
The mobile systems currently in use on the Phoenix freeway system will increasingly be moved to outlying areas around the state to address serious injury and fatal collisions statewide.
Mobile systems typically produce fewer citations than stationary systems. There are currently 42 mobile systems in operation.
AIMING FOR RED-LIGHT RUNNERS
Red-light systems have the potential to significantly impact highway safety. Intersection collisions on state highways frequently involve high speeds making them particularly dangerous.
Signaled intersections on state highways are being considered for photo enforcement because of the potential for reducing serious injury and fatal collisions. Like mobile systems, red light photo enforcement systems also produce lower numbers of citations when compared to stationary speed systems.
While there continues to be a large amount of discussion about photo enforcement and motives for its implementation, the Arizona Department of Public Safety remains committed to the statewide program for one simple reason. We believe it saves lives.
More information about the program can be found at http://photoenforcement.azdps.gov/.
Cmdr. Thomas Woodward directs the Arizona Department of Public Safety’s East Metro Bureau and is part of the command team that oversees implementation of the state’s photo enforcement program.