The Bright Side of Crime
Note: There is a new research assistant here in the Freakonomics office, and his name is Ryan Hagen. He’s 24 years old, a graduate of N.Y.U. (he majored in English and American literature), and for the past two years he’s worked as a research associate for N.Y.U.’s Center for Catastrophe Preparedness & Response. We are very happy to have him here performing various functions — including, here, his first blog post. — SJD
In terms of nighttime safety and security, it can be easy to mistake a brightly lit place for a well-lighted one. The New Yorker‘s David Owen explains:
Lighting is effective in preventing crime mainly if it enables people to notice criminal activity as it’s taking place, and if it doesn’t help criminals to see what they’re doing. Bright, unshielded floodlights — one of the most common types of outdoor security lighting in the country — often fail on both counts, as do all-night lights installed on isolated structures or on parts of buildings that can’t be observed by passersby (such as back doors). A burglar who is forced to use a flashlight, or whose movement triggers a security light controlled by an infrared motion sensor, is much more likely to be spotted than one whose presence is masked by the blinding glare of a poorly placed metal halide “wall pack.”
He’s describing the work of Marcus Felson, a criminologist at Rutgers University who specializes in discovering means of reducing opportunities for people to commit criminal acts — through proper lighting, among other tactics.
The key to increasing visibility at night is to heighten light contrasts without producing deep shadows and obscuring vision (it can take your eyes up to an hour to adjust to darkness after exposure to a light source as dim as a desk lamp). This is true for reducing not just crime, but also nighttime accidents on roadways and at airports. Owen points out that the California Department of Transportation has successfully lowered the state’s traffic accident rate by replacing some of its continuous overhead lighting with passive reflectors. Also, airfield runways maximize visibility for pilots by using guide lights that delineate the edges and centers of landing strips, rather than wide-area floodlights.
But if less can be more, at least when it comes to lighting our way at night, what accounts for the popularity of high-intensity-discharge xenon headlights among car buyers?
(HT: Schneier on Security)