Does High-Tech Highway Design Make us Less Safe?

When it comes to planning highways and roads, greater convenience does not necessarily mean fewer accidents. Perceived advances in safety—wider, straighter roadways and more electronic traffic signals—may make drivers too comfortable. That’s when accident rates start to rise. Contributing editor Glenn Reynolds looks at safety practices in our infrastructure and asks: Are our roads making us less safe? [via popularmechanics]

Reading Tom Vanderbilt’s latest book, Traffic: Why We Drive the Way We Do (and What It Says About Us), I was struck by a recurring theme: Making things safer may actually make them more dangerous. I wonder if it’s a lesson that also applies off the road.

Vanderbilt describes driving along a narrow, twisting road in Spain, where he navigated hairpin turns with few guardrails or warning signs over steep drop-offs. The result: “I drove as if my life depended on it.” But when he reached a four-lane highway with gentle curves, good visibility and little traffic, “I just about fell asleep and ran off the road ... Lulled by safety, I’d acted more dangerously.”

There is a fair amount of scientific evidence that backs up Vanderbilt’s insights. Give people antilock brakes, airbags and other safety devices, and they “consume” the safety improvements by driving more aggressively. This phenomenon is called the Peltzman Effect, after economist Sam Peltzman, who first wrote about it in 1976. The decades-long effort to make highways straighter, wider and better-marked, with more guardrails and rumble strips, has eliminated one class of dangers only to foster another: the complacent driver with
a cellphone in one hand and a cup of coffee in the other, steering the vehicle with a knee while occasionally glancing at what’s ahead.

Meanwhile, modifying roads and intersections so drivers are less comfortable—by making driving, in some ways, more dangerous—forces people to slow down and pay attention, producing a change in behavior that, paradoxically, results in more safety. This is also true for pedestrians, who Vanderbilt says are more cautious away from crosswalks than within them because they don’t know if cars will actually stop.

Likewise, traffic circles and squares, which demand a driver’s full attention, turn out to be both safer and better at handling large volumes of traffic than traditional four-way intersections with traffic lights. In the former, people focus on what’s going on; in the latter, they relax and expect the traffic signals to do all the work. Drivers in traffic circles also communicate more with hand signals and eye contact. As Vanderbilt notes, when a traditional four-way intersection with lights was turned into a traffic square, “The responsibility for getting through the intersection was now up to the users, and they responded by communicating among themselves. The result was that the system was safer, even though the majority of users, polled in local surveys, felt that the system was more dangerous!”

Vanderbilt also says that change causes people to pay more attention, and hence drive more safely. In 1967, when Sweden switched from driving on the left to driving on the right, many people predicted that accidents would increase. But accident rates dropped noticeably, and took a year to return to the pre-changeover level. The change, and the fear of accidents it produced, caused people to drive more carefully. The lesson here is that familiarity breeds slackness, and regular challenges encourage mindfulness and attention. Instead of designing roads and devices to accommodate people who are dozing through life, we might produce better performance by designing things with an eye toward engaging attention.

Famed Dutch traffic engineer Hans Monderman once said: “When you treat people like idiots, they’ll behave like that.” Monderman’s philosophy is, instead, to design things so that people are called on to use their wits—at least within limits. When that happens, things often wind up safer.

I’m not ready to plow up all the interstates and replace them with cow paths, but this approach does ring true. In our modern world, lots of things compete for our attention, and where we can take things for granted, we’re likely to do so, even if it’s not really a good idea.

The safety-through-danger approach extends to cars. Modern cars are quiet, powerful and capable of astonishing grip in curves, even on wet pavement. That’s swell, of course, until you suddenly lose traction at 75 mph. The sense of confidence bred by all this capability makes us feel safe, which causes us to drive faster than we probably should. We don’t want to make cars with poor response, but perhaps we could design cues—steering-wheel vibration devices, as in video games?—that make us feel less safe at speed and encourage more care. Designers could make cars feel faster at lower speeds, instead of slower at higher speeds. Done right, this might even make driving more fun. In college I drove an Austin-Healey 3000 that somehow felt faster at 45 mph than my Mazda RX-8 (or even my Toyota Highlander Hybrid) feels at 75 mph. That was a good thing.

This approach could be taken beyond the world of personal transportation. We’re in the current financial mess in part because things that were actually dangerous—from subprime mortgages to risky financial instruments that no one fully understood—felt safe and ordinary. Modern financial markets, with computers, regulations, deposit insurance and bond ratings, felt as routine and as smooth as that four-lane highway in Spain, causing a lot of people who should have been paying attention to doze off. Investors might have been more careful if it had felt like they were driving down a twisty mountain road with no guardrails, especially since we really were engaged in the financial equivalent of high-speed mountain driving, only without the discipline of fear.

In athletics, protection sometimes leads to more risk-taking. Research has shown that skiers who wear helmets ski faster than those who do not. Likewise, firearms instructors are quick to stress that the safety on a gun doesn’t actually render the weapon safe, just marginally safer, so that all usual precautions still apply. And I noticed when scuba diving with a spare air cylinder that instructors were concerned these backups would become popular with inexperienced divers and that this reliance might breed carelessness with the main equipment.

The traffic example demonstrates a general phenomenon of modern society: With the best of intentions, we tend to replace situations that call on the use of our wits with situations that we can sleepwalk through, and the solutions to matters with any serious consequences are postponed to the indefinite future. That’s a comfortable way to live, and there are good reasons to be glad of it—we’re not in a situation where one bad harvest means starvation, after all—but if you can postpone problems indefinitely, a lot of problems will be postponed. Yet the future eventually arrives.

As Vanderbilt observes, “The pursuit of a kind of absolute safety, above all other considerations,” can make things less safe. For designers, lawmakers and the rest of us, it’s worth keeping this in mind. Complacency and comfort have their place, but they also have their perils, as we are learning.

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