You don't have to drive far in a typical American town before you see it: A pictographic image of a child (implied to be a boy), perhaps chasing a ball, perhaps poised in midstride, perhaps atop a seesaw, perhaps with a jaunty cap, perhaps with a companion or parent. And then, some variation on these words: "Slow: Children at Play." As a child, you may have played near such a sign. Maybe you made the callous jokes about "slow children" playing. You probably assumed they were there for a good reason; that they made your community a safer place for children; that their message, beaming with retro-reflective glory, was duly observed by drivers, who suddenly snapped to hyper-vigilant readiness at the wheel, scanning the road in a methodical, Terminator-like radar-sweep.
You would be wrong.
Despite the continued preponderance of "Children at Play" on streets across the land, it is no secret in the world of traffic engineering that "Children at Play" signs—termed, with subtle condescension, "advisory signs"—have been proven neither to change driver behavior nor to do anything to improve the safety of children in a traffic setting. The National Cooperative Highway Research Program, in its "Synthesis of Highway Practice No. 139," sternly advises that "non-uniform signs such as "CAUTION—CHILDREN AT PLAY," "SLOW—CHILDREN," or similar legends should not be permitted on any roadway at any time." Moreover, it warns that "the removal of any nonstandard signs should carry a high priority."
There are several reasons engineers don't like the signs. The first, and most simple, is that if you are driving in an area where children are actually playing, you will, it is hoped, notice them before you notice a sign warning you of them. Or, more to the point, that you will have noticed that you are driving in an area (say, a residential street) where there are likely to be children about. "I find it amazing that people think that a 30-in X 30-in square sign (that is only a little less than 6.25 square feet of sheeting material when you make the corners rounded) will make a difference in driver behavior," one engineer complained on an Internet forum. "If the driver does not notice the characteristics of a neighborhood as they drive down the street, why would they notice a sign as they pass it, or remember it for more than a few seconds once they have passed it."
Another problem is that, as with "Bridges Freeze Before Roadway" signs on a hot summer day, the many times a driver will drive down a street when no children are playing gradually condition him to disregard the warning, or even view it with a bit of suspicion. Who hasn't gone past a rusting "Deaf Child" sign and wondered if the child hasn't long since grown up or moved away?
The Federal Highway Administration, in its Manual of Uniform Traffic Control Devices, the sacred Ur-text of road signage, does not sanction "Children at Play" signs. It notes: "The use of warning signs should be kept to a minimum as the unnecessary use of warning signs tends to breed disrespect for all signs. In situations where the condition or activity is seasonal or temporary, the warning sign should be removed or covered when the condition or activity does not exist."
There are other problems. Does the presence of a "Children at Play" sign subtly hint that there aren't children at play in other locations? Does the sign breed a false sense of security? And does it, as some engineers suggest, encourage the idea that the street is to be used as a play area—which could, as one report suggests, expose municipalities to the possibility of tort liability?
If the sign is so disliked by the profession charged with maintaining order and safety on our streets, why do we seem to see so many of them? In a word: Parents. Talk to a town engineer, and you'll often get the sense it's easier to put up a sign than to explain to local residents why the sign shouldn't be put up. (This official notes that "Children at Play" signs are the second-most-common question he's asked about at town meetings.) Residents have also been known to put up their own signs, perhaps using the DIY instructions provided by eHow (which notes, in a baseless assertion typical of the whole discussion, that "Notifying these drivers there are children at play may reduce your child's risk"). States and municipalities are also free to sanction their own signs (hence the rise of "autistic child" traffic signs).
Which is not to discount the concern of parents, or anyone else, about traffic speeds on residential streets (even if, as police have told me on more than one occasion, it's often the very same residents who are the problem). In fact, as much as engineers know about how "Children at Play" signs do not work, one might argue there is much they do not know about how they work. As one report notes, "though these all discourage the use of such signs, none of them cites specific research demonstrating that these signs are ineffective." In other words, even if the "Children at Play" signs are a placebo, that doesn't mean they've been tested with the same rigor as a new drug.
One of the things that is known, thanks to peer-reviewed science, is that increased traffic speeds (and volumes) increase the risk of children's injuries. But "Children at Play" signs are a symptom, rather than a cure—a sign of something larger that is out of whack, whether the lack of a pervasive safety culture in driving, a system that puts vehicular mobility ahead of neighborhood livability, or non-contextual street design. After all, it's roads, not signs, that tell people how to drive. People clamoring for "Children at Play" signs are often living on residential streets that are inordinately wide, lacking any kind of calming obstacles (from trees to "bulb-outs"), perhaps having unnecessary center-line markings—three factors that will boost vehicle speed more than any sign will lower them.