Consider the stop sign. It seems innocuous enough; we do need to stop from time to time. But think about how the signs are actually set up and used. For one thing, there’s the placement of the signs—off to the side of the road, often amid trees, parked cars, and other road signs; rarely right in front of the driver, where he or she should be looking.
Then there’s the sheer number of them. They sit at almost every intersection in most American neighborhoods. In some, every intersection seems to have a four-way stop. Stop signs are costly to drivers and bad for the environment: stop/start driving uses more gas, and vehicles pollute most when starting up from rest. More to the point, however, the overabundance of stop signs teaches drivers to be less observant of cross traffic and to exercise less judgment when driving—instead, they look for signs and drive according to what the signs tell them to do.
The four-way stop deserves special recognition as a masterpiece of counterproductive public-safety efforts. Where should the driver look? What must he remember? State driving manuals can be surprisingly coy about exactly what drivers should do at four-way stops. The North Carolina Driver’s Handbook, for example, doesn’t mention four-ways as a separate category at all. Yahoo Answers imparts the following wisdom: “The rules for a four-way stop are like those for a two-way: Stop and look for oncoming traffic, and proceed when it is safe to do so.” So far so good, but then: “You may occasionally arrive at a four-way stop sign at the same time as another driver. In such cases the driver to the right has the right of way. However, not all drivers know this. If someone to your left decides to go first, let them!” Thanks! But remind me: aside from bewildering the driver, what’s the point of stopping traffic in all four directions?
The four-way stop weakens the force of all stop signs by muddling the main question drivers need to answer, namely: Which road has priority? And indeed, American drivers have apparently become confused enough by this question that some communities are now beginning to affix another sign to the poles of stop signs that aren’t four-way, warning cross traffic does not stop.
Speed limits in the U.S. are perhaps a more severe safety hazard than stop signs. In many places, they change too frequently—sometimes every few hundred yards—once again training drivers to look for signs, not at the road. What’s more, many speed limits in the U.S. are set in arbitrary and irrational ways. An eight-lane interstate can have a limit of 50 to 70 mph or more. What makes the difference? A necessarily imperfect guess at probable traffic conditions. The road may sometimes be busy—so the limit is set low. But sometimes the road is not busy, and the safe speed is then much higher than the limit.
A particularly vexing aspect of the U.S. policy is that speed limits seem to be enforced more when speeding is safe. As a colleague once pointed out, “An empty highway on a sunny day? You’re dead meat!” A more systematic effort to train drivers to ignore road conditions can hardly be imagined. By training drivers to drive according to the signs rather than their judgment in great conditions, the American system also subtly encourages them to rely on the signs rather than judgment in poor conditions, when merely following the signs would be dangerous.
Which brings me back to North Glebe Road in Arlington. It turns out that the speed signs do perform an important safety function: in wet weather, many drivers had taken the curve too fast; traffic authorities have substantially reduced accidents on the curve by adding the 15-mph warning sign, and they would be foolish to remove it, absent larger changes in American traffic policy. But this is emblematic of the sort of signage arms race that has become necessary in the U.S. When you’ve trained people to drive according to the signs, you need to keep adding more signs to tell them exactly when and in what fashion they need to adjust their behavior. Otherwise, drivers may see no reason why they should slow down on a curve in the rain.