Nashville's News Channel 5 posts this headline:
Red Light Cameras Cut Down on Crashes
It's referring to an article in the Clarksville Leaf Chronicle with this headline:
Red light cameras working in Clarksville, police chief says
But look at the actual numbers and it's not at all clear that the cameras are "working," at least if you believe "working" to mean "making the roads safer." What's clear is that local authorities want to give the impression that the cameras are preventing accidents, even if the numbers don't bear that out. The police chief focuses on side-impact collisions, which fell from 72 in 2008 to 64 in 2009 after the cameras were installed. That's a modest drop, and it wasn't consistent across the city. For example, one intersection had four side-impact collisions in 2008, five in 2009, and has seen 11 already this year.
In fact, overall collisions are up at the intersections where Clarksville has installed red light cameras (a result we've seen nearly everywhere they've been installed). The city just chooses to ignore rear-impact collisions when evaluating the cameras. Those collisions increased from 138 in 2008, to 173 in 2009, to 169 through October of this year. It's true that side-impact collisions are generally more dangerous than rear-impact collisions. But even taking that into consideration, it's a bit of a stretch to say that a decrease of eight side-impact collisions coupled with an increase of 25 rear-impact collisions shows that the cameras are preventing accidents.
But there is one way that the cameras are working out quite well:
Clarksville’s red light camera program has already issued more than 10,000 tickets, bringing in about $1 million in revenue.
Interestingly, about $600,000 of that revenue goes to Redflex Traffic Systems, Inc., the company that manufactures and operates the cameras. And how's this for a display of twisted incentives:
Buoyed by the program’s early results, police plan to expand the program to two other intersections, Highway 76-Interstate 24 and Fort Campbell Boulevard-Lafayette Road. Both are in the top 10 in number of accidents.
Ansley said they have to wait for Redflex’s approval, because any new intersections would have to be profitable for the company to cover the cost of the cameras.
So Redflex gets to dictate where the cameras go. Which means that if the cameras really are effective at preventing accidents and red light runners, as the intersections get safer, Redflex's profit margins (and city revenues) get thinner. If I were a Redflex executive, I'd put the cameras at intersections where there's lots of red-light running, but where cameras aren't likely to be very effective at preventing it.
The best approach doesn't bring in any revenue, for camera makers or city governments: Lengthening the duration yellow lights has proven to be much more effective at preventing accidents than cameras. Which of course is why several cities have been caught making intersections more dangerous by shortening yellow lights in order to generate more tickets.