The risk of safety technology.

You probably have heard of truck drivers driving faster and tailgating because they have ABS. And people often drive a bit faster when road lighting improves at night. Dr. Nicholas Ward, associate director of the ITS Institute Human Factors Research Laboratory in Minneapolis, says such behavior is hardly new. The more things change, the more they stay the same.

Indeed, since 1923 – despite improvements in road design, creation of the Interstate system, installation of millions of traffic lights and adoption of seat belts and crash-resistant cars – the death rate per 100 million miles of driving has remained constant per 100 million miles of driving.

After graphing changes in accident rates, Ward came to a simple but unsettling conclusion. “We seek and accept a certain amount of risk. No matter what improvements are made, we consume the safety benefit to drive faster or to drive more.”

A good example of how we seek risk is what happened in Sweden in September 1967 when the country reversed driving lanes. That was one of the lowest accident years in the country’s history – apparently because drivers knew driving would be risky and drove more cautiously. The bottom line: Human beings crave a certain level of perceived danger and will always tend to behave in such a way as to, as Ward puts it, “reclaim a certain level of risk.”

The point is: Any technological change will “achieve a benefit only if drivers do not then change their driving behavior.” Such behavioral changes include driving faster, increasing miles driven or becoming complacent and, therefore, less attentive. Less-attentive drivers respond more slowly to a problem ahead.

“Drivers adapt to training and new technologies,” Ward says. “So we must always include measures to deal with their changes in behavior.” An example would be insisting that drivers not shorten following distance – even a little – just because their rigs are ABS-equipped.
The phenomenon isn’t limited to safety technology; safety training also can induce undesirable adaptation. One carrier, for example, gave drivers a substantial course in driving on slippery roads. There was no safety benefit, however. Rather than using this training to avoid and maneuver out of skids, the drivers merely gained confidence from their newfound expertise and drove faster in adverse conditions. So an anti-skid course needs to be accompanied by strong warnings to slog along just as slowly as ever through the ice and snow.

Technology, says Ward, “may circumvent rather than remove the root cause (of crashes), and therefore redistribute, rather than reduce, the risk.” This can happen, Ward says, when a driver spends a lot of time in a truck with adaptive cruise control. After running along for hours with the system holding the following distance, the driver can become so inattentive that he takes an inordinate amount of time to react when something happens ahead. Drivers may also dial in a shorter-than-normal following distance. Thus, the net effect of installing adaptive cruise can be an increase in the risk of running up on the vehicle ahead.

Driver fatigue warning systems also can have a negative effect. The driver may assume he isn’t tired until the system goes off. In so doing, he ignores signals from his own body about his alertness. Fog warning systems often cause drivers to run at a much higher speed in adverse visibility conditions. Adapting ABS may ultimately result in a substantial reduction not only in following distance but in driver skill in braking smoothly and maneuvering his vehicle during braking.

The message is clear: Drivers need to receive serious retraining when high-tech safety devices go on the vehicles they drive. That retraining must somehow convince them to drive exactly as if all the added safety devices simply were not there.

John Baxter is senior associate editor of Commercial Carrier Journal. E-mail