Red light cameras save lives. Photo speed cameras probably don’t.
From 2001 to 2019 the City of Phoenix set up a handful of red-light cameras at strategic intersections with frequent violent crashes. The city council discontinued use of red-light cameras in ’19 because of concerns about “privacy, effectiveness and discrimination”.
Last year Phoenix Police asked the Council to reinstate them. The Council did so this week, approving the installation of 10 red light cameras across strategic Phoenix intersections. The Council was receptive to adding more red-light cameras in the future depending on the results.
Red-light cameras are coming back to Phoenix
In addition to the ten cameras, the Council approved deploying 6 speed cameras (they say to be moved throughout the city every four to six weeks at intersections with a high number of speed-related crashes and school zones).
What’s the Public Health Evidence?
- Red-light running cameras (evidence-based)
- Speed cameras at green lights (NOT evidence-based)
- Fixed midblock speed cameras posted on long stretches of road (NOT evidence-based)
- Portable speed towers (NOT evidence-based except around schools)
- Mobile speed vehicles (NOT evidence-based except around schools)
Public health literature suggests well-placed red-light cameras save lives and reduce severe injuries. Photo speed cameras probably don’t.
Data collected by Phoenix PD suggests that the 12 cameras that had been used prior to 2019 resulted in a 31% drop in red light running crashes at the cross-streets they were used and a 57% drop in red light running crashes in the directions the cameras were facing.
A landmark study for photo enforcement was done by Retting et.al. and published in the American Journal of Public Health examining the impact that photo enforcement had in Oxnard CA after they implemented their photo enforcement program.
Intersections that had red light cameras installed had a 29% reduction in injury crashes. T-bone crashes from red light running were reduced 32% and violent T-bones causing injuries were reduced 68%. Overall accidents at the intersections were reduced by 7%.
There’s less clear evidence that speed cameras are effective public health interventions. There’s almost nothing in the literature that I could find one way or the other for speed cameras.
However, a few years ago a research team that included Dr. Chengcheng Hu, director of biostatistics for the Phoenix campus of the UA Mel and Enid Zuckerman College of Public Health, Dr. Steven Vanhoy, a recent graduate of the UA College of Medicine – Phoenix, and several colleagues from Banner – University Medical Center Phoenix, offers some insight.
The researchers examined crash data along a 26-mile segment of Interstate-10 in Phoenix where speed cameras had been placed every 2 miles as well as a 14-mile control segment where no cameras had been deployed.
They compared crash data from Jan. 1 to Dec. 31, 2009 (when cameras were in place) to data from Jan. 1 to Dec. 31, 2011 (after the cameras had been removed). They found that the removal of the photo radar cameras was associated with a two-fold increase in admissions to Level 1 Trauma Centers from car crashes in the areas where the cameras were removed.
Editorial Note: Nobody likes getting a traffic ticket, but photo red light enforcement can significantly reduce severe injuries if placed in the right intersections. There’s less evidence that photo speed enforcement works.
When photo speed cameras are used as a revenue generating tool (as it is in Paradise Valley – which places speed cameras practically every 500 meters throughout the town especially on roads with artificially low speed limits) it undermines public support for photo enforcement as a public health intervention.
Unless jurisdictions like Paradise Valley (who use photo enforcement as a revenue tool as opposed to a public safety tool) cool their jets, we risk an eventual statewide preemption of all photo enforcement, to the detriment of public health.
