The quest to design a better stop sign.

How we get from here to there.
May 25 2010 12:32 PM


Is it possible to design a better stop sign?

Check out our Magnum Photos gallery of stop signs.

(Continued from Page 1)

John Staddon, a professor of psychology at Duke University, notes another problem: "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." He reserves particular opprobrium for the four-way stop. The rules of engagement are somewhat informal—most drivers take it to be "first in, first out." What if two drivers arrive at the same time? Traffic laws state the driver to the right has the right of way (good luck with that). If four cars arrive simultaneously—well, it's best that they do not. "Remind me," asks Staddon, "aside from bewildering the driver, what's the point of stopping traffic in all four directions?" The four way stop, he argues, "weakens the force of all stop signs by muddling the main question drivers need to answer, namely: Which road has priority?" (One thing four-way stops have in their favor, however, is a superior safety record to two-way stops—and to traffic signals, for that matter).

Which brings us back to Lauder's suggested "Take Turns" sign. In the rarefied TED air, where the world is being saved and the old certainties boldly challenged by 15-minute PowerPoints, the idea seems sensible and perhaps even inspired. But the world of traffic is a more complicated place. For one, given the lack of compliance at stop signs, what's to ensure proper behavior in a less clearly demarcated situation? What if three cars approach simultaneously? What if a driver approaching fast on the main road assumes that his speed gives him priority, while the entering driver thinks the fact that he's pulled up to the new sign first gives him priority? (The costs estimated by Lauder in lost wages and fuel are vastly less than the costs of a fatal crash). And what should cars do if pedestrians are present? Lauder is right about the futility of that intersection, but wrong in his solution: If the money saved could indeed buy the adjacent property, then the best solution would be to simply install the safest and  most smoothly flowing solution of all: A roundabout.


Of course, there are plenty of intersections in America that are "uncontrolled." In Portland and Seattle, for example, local neighborhoods are filled with any number of four-way intersections without any signs. And somehow drivers continue to negotiate these intersections safely, year after year, in the absence of clear instruction.           

If traffic volumes rise above a certain threshold or a crash pattern evolves, other measures are taken—a roundabout may be built, traffic-calming measures deployed, or signage installed. And it is these latter cases, when some form of signage is required, that brings us to the question: Does the stop sign need to be reformed? Actually, the "stopping occasion," as the viral parody put it, has been tinkered with quite a bit. Engineers have sought to remedy visibility and compliance problems by adding any number of add-on accessories to the stop sign, among them "stop lines" painted on the road, rumble strips in advance of the stop, or flashing red lights on top of signs. One study tested a stop sign beneath which were posted a pair of LED eyes, roving back and forth—the idea was a meant as a reminder to look both ways. The study reported a reduction in "right-angle conflicts"—the most dangerous thing about intersections—though this may have merely been a novelty effect.

Interestingly, eyes were more effective than a "look both ways" text add-on. But what if the sign is not visible to begin with—what if it's obscured by a low-hanging branch or a double-parked truck? That's the thinking behind a new stop sign treatment being tested in Nye County, Nevada. Called "Drivers Alert," it attaches a secondary stop sign to the back of the stop sign across the intersection, giving the driver two chances to see the sign. It also graphically advises whether cross traffic is meant to stop or not, a fix that others have suggested. (Some engineers have proposed making stop signs at two-way stops orange, to immediately distinguish them from four-way stops.) Whether this effort is superfluous given existing visibility-reinforcing treatments (e.g., the stop bar) or, per Staddon, simply gives the dumbed-down driver more things to look at apart from what's happening on the road itself is open for debate.

The proposed solution also raises the interesting question of how we see (or do not see) stop signs. In large part, we see stop signs because they tend to exist where we expect them to exist (trouble begins when our "expectancy" is violated). But in crashes, the largest problem is not visibility but driver behavior—drivers either do not come to a full stop or pull out too close to an approaching car (one study found that only 17 percent of crashes at stop-sign controlled intersections involved drivers who "blew" the sign). In this regard trying to improve driver behavior through better signage is as futile as fighting illiteracy with better fonts.

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