How successful are red light cameras at improving safety? Data on the effectiveness is nothing short of compelling.

My friend Heidi, mother of two, was recently hit by a car. In a crosswalk, no less. The driver? Chatting on the phone, she blew through the light. Heidi’s surreal summersault began. First she hit the hood, then the roof, and eventually the pavement. Next stop—the ER.

Intersection accidents like this happen all the time. There are more than 200,000 annually in the U.S. That’s twice the headcount of the People’s Republic of Boulder.

Blowing red lights is even more common—in some Colorado intersections it happens about every 10 minutes. It isn’t usually because drivers are intoxicated, but because they’re going too fast to stop, on the phone, distracted, or in a hurry.
You know the feeling—“I can make it.” Or “Oh, drat, I blew it.”

Yet at intersections where photographic ticketing devices are present, drastically fewer such events occur—both at the monitored signal, and at other stoplights in the vicinity.

So why is it that every year our state representatives support bills to ban red light cameras, along with photo radar systems used to reduce speeds near schools, construction zones and the like? Are they trying to appease constituents, or are they privy to data that the rest of us don’t know about?

They claim such systems jeopardize public safety, are aimed at generating municipal revenue, or invade privacy. In some ways, such cameras do smack of Big Brother, and people understandably fear that successful programs will lead to even more monitoring. Seems like a slippery slope.

But how successful are these systems at improving safety? I decided to investigate, with focus on photo red-light cameras, where there is abundant, statistically rigorous, peer-reviewed data available.

In general, the data on the effectiveness of these cameras seems nothing short of compelling. Especially if you don’t cherry-pick factoids to suit your position, as seems to happen with arguments used by proponents and opponents of such cameras. Unlike opinions, not all data are valid or equal in stature.

In nearly every country where such cameras have been employed in traffic management plans, they tend to drastically reduce violations, injuries and fatalities. And they typically have a spillover benefit, reducing red light running at nearby intersections. In most municipalities, the revenue they generate is almost inconsequential, especially when compared to system installation and maintenance costs and the personnel and infrastructural costs required to achieve similar improvements in safety. Finally, their financial impact pales in comparison to the liability and “costs” of avoidable permanent injuries and fatalities.

But, like speed violation cameras, red light cameras are no panacea. Here in Colorado, they’re one tool in the suite of countermeasures used to make intersections safer. They’re employed in sync with other traffic engineering solutions, such as extending the time yellow lights are illuminated or programming intersection lights so they all are simultaneously red for a moment. Like automated cameras at railroad crossings and construction zones, red light cameras appear to be optimally effective in accident-prone intersections where police monitoring isn’t practical or where physical infrastructure can’t easily be changed, such as by replacing an intersection with a roundabout.

But was my friend Heidi’s experience just a fluke? Not really—most of us are two degrees of separation from an incident. For example, every time we enter a busy intersection, we’ve got about a 1 in 1,000 to 1 in 15,000 chance of encountering a red-light runner. Seems low—until one considers how many stoplights we drive through every day. And how many days we drive each year. Whoa.

But should safety trump privacy, or become an inroad for government surveillance? It seems the Supreme Court as well as local courts have spoken to the heart of the issue. Driving on a public road does not afford Fourth Amendment privacy protections, largely because driving is a regulated activity that occurs in public, not in private. Because your driving is a granted and agreed-upon privilege, municipalities have the right to deter you from and cite you for breaking the law.

Concerned about Big Brother? Such automated systems are less invasive overall because they don’t profile drivers, nor do they examine vehicle interiors or driver/passenger behaviors like police officers might. And they certainly don’t check to see if the pulled-over driver has the munchies.

And my friend Heidi? She was luckier than most. After surfing with her last week, the only thing different I noticed was a big bump of scar tissue on her shoulder. And a renewed sense of caution in the street.

James Hagadorn, Ph.D., is a scientist at the Denver Museum of Nature & Science. Suggestions and comments are welcome at jwhagadorn@dmns.org.