Traffic signal at Tamil Nadu. (c) 2011 Thamizhpparithi Maari (CC BY SA 3.0)

Security Lights Increase Vandalism

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Surely keeping the lights on reduces vandalism, right? If you think that I can see you, then you are less likely to commit a crime.

Not so fast, according to one commenter at Half Bakery. ldischler pointed out that security lighting actually increases vandalism.

That’s a bold claim but it may be right. And the underlying principle may be vital to succeeding in work.

Conventional wisdom suggests that light reduces crime. That’s why outdoor lights are often called “security lights”. School districts across the U.S. are turning conventional wisdom on its head by turning off lights on school grounds.

The results have been impressive. Annual energy savings can add up to hundreds of dollars per school. Significant decreases in vandalism have been documented since the “Dark Campus” policies have gone into effect. Here are three examples. [from “Dark Campus Programs Reduce Vandalism and Save Money” (PDF)]]

The reason that this works is that no one is there. The main problem is vandalism. As Sam Wolf, director of security for the San Antonio ISD said in the article, “I remember as a kid, we never hung around in the dark. We hung around a street light. We wanted to see who was with us.”

People don’t like to be in the dark. Even kids who are spray painting.

Christopher Alexander’s A Pattern Language: Towns, Buildings, Construction (Center for Environmental Structure Series) (1977) talks about the issue of light pools and how attracted we are to it.

People are by nature phototropic — they move toward light, and, when stationary, they orient themselves toward the light. As a result the much loved and much used places in buildings, where the most things happen, are places like window seats, verandas, fireside corners, trellised arbors; all of them defined by non-uniformities in light, and all of them allowing the people who are in them to orient themselves toward the light… since settings are defined by “places”, which in turn seem often to be defined by light, and since light places can only be defined by contrast with darker ones, this suggests that the interior parts of buildings where people spend much time should contain a great deal of alternating light and dark. The building needs to be a tapestry of light and dark. [Pattern 135, “Tapestry of Light and Dark”, pp. 645]

These spaces of light and dark, or lighter and darker, make a natural place as opposed to the unnatural uniform lighting of most buildings. This need for spaces of light and dark explains why we have an aversion to using large overhead fluorescents at home even though we use them at work.

Cutting edge workplaces have more dis-uniform lighting, looking more natural. Even at traditional workplaces, specialist workers will often unscrew the lights above them and rely on desk lights, even if they are restricted to the fluorescents under their overhead storage bins within a cubicle.

Security lighting doesn’t just prevent vandalism but also reduces the risk of violent crime by making more visible. There are fewer places for muggers and rapists to hide under large lighting.

Most of the time, though, we don’t need large security lights on. We can turn them off over our parking lots after hours, and perhaps even turn them off around our buildings. With the nightcams widely available (basically low light level amplifiers) even for the consumer, there’s not as much reason to continue using so many lamps.

That said, most people still don’t want to be in an entirely darkened area. And few stay that way. During World War II, many a ship (it is said) was sunk because a careless sailor lit a cigarette on deck at night. The light could be seen for miles in the darkness and the submarines took advantage. The same occurs today, and worse since mobile phones light up. Visitors to darkened areas would stand out.

For the dark campus to work, the campus has to be off-limits during all dark hours and the idea has to be well communicated. This lets the community be on the watch for lights.

But where you expect people you will need proper security lighting.

You still don’t need as much as most use. You have to think of how people see at night.

Most organizations put up the brightest light possible thinking that it will illuminate the area the most; that is, make things the most clear. If you are outside the lighted zone that may be true. But it also creates too great a contrast with the darkness around the lighted zone. Such a contrast with the shadows makes them become darker to human perception, increasing the risk since you can’t see out of the lighted zone any more. Your eyes can’t adjust to the stark contrast quickly enough.

Lower light levels are actually superior for security because they illuminate what needs illumination while allowing you to still see in the shadows. Sodium lights apparently work better for this and they seem to last a long time.

And hood the light so that it illuminates the ground and not the sky, of course.

But the idea that what you think will accomplish your goal and what will is often counter-intuitive. Test your ideas. What you believe works may not be what’s most effective.

Or effective at all.

Image credit: Traffic signal at Tamil Nadu. © 2011 Thamizhpparithi Maari (CC BY-SA 3.0). Via Wikimedia Commons.

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