A new study showing that bad roads contribute for more than half of the traffic fatalities in the US has stirred a lot of debate. From 1979 to the present, most studies have shown that driver error is most responsible for traffic collisions. Are bad roads at fault and will improving the roads reduce the fatality rate? There is some data to show that the traditional methods of road improvement may actually make the roads more dangerous.
A lot of the nation’s highways are in bad shape, including bridges and overpasses. There is no doubt that we need more and better roads to relieve the traffic burden; especially in large cities. However widening roads, adding more signs and clearer lane markers may not be the best answer. There have been some arguments claiming that widening roads and painting clearer markings will lead to the “Peltzman Effect”.
Sam Peltzman, a professor of Economics at the University of Chicago theorized that people tend to respond to safety regulations or safety technology by engaging in more dangerous behavior. He felt that people adjust their behavior to a regulation in ways that counteract the intended effect of the regulation. One study that found the Peltzman Effect to be true looked at increased safety technology in NASCAR race cars. The study revealed that safety improvements in race cars have resulted in riskier driving behavior and an increase in the number of collisions on the raceway.
The Insurance Institute for Highway Safety (IIHS), in looking at new technology to make cars safer, warned that systems designed to keep a car from automatically straying from the lane or from coming too close to a vehicle ahead are great in theory but they feel it will give drivers a false sense of security leading them to take their eyes off the road more often or allowing them to become more distracted.
The intended effect of building wider, clearer roads is to improve the flow of traffic and to cut down on injuries and deaths due to collisions. The Peltzman Effect however says that, as roads are improved, drivers feel they can take greater risks and the average speed on the roadway increases. As a result, the intended effect of making the road safer is offset by riskier driving behavior and the rate of collisions is basically unchanged.
As a reaction to this, traffic engineers in cities around the world have moved to a European innovation known as “Traffic Calming”. To slow or calm traffic, traffic calming devices include speed bumps, roadway restrictions, and signs painted on the road surface. Probably the best and most visible examples of traffic calming procedures are the traffic circles that are replacing traditional four-way intersections. Traffic circles allow traffic to move through an intersection without the use of traffic lights. Traffic circles force drivers to slow down upon entering but keep traffic moving more smoothly due to the lack of traffic lights.
Traffic calming measures have been implemented from Florida to Washington State but city planners are finding that they are very expensive to install and maintain. Traffic calming is most often seen on urban streets with lower speeds. Studies have found that implementing traffic calming measures on major highways have had little impact on speed control.
Hans Monderman, a Dutch traffic engineer looked at some of the traffic calming procedures and felt they were ineffective. Monderman rejected the notion that wider roads and more warning signs created a safer environment. He was hired to look at a street in the Dutch village of Oudehaske, where speeding drivers had struck and killed two children. Instead of employing the typical traffic calming devices, Monderman removed the curbs, took out the signs, and used paving bricks that had the effect of making the road seem narrower. The effect was to create enough uncertainty in the minds of drivers that traffic immediately slowed down and the average speed was dramatically reduced. Without signs or lane markings, the effect changed driving behavior making drivers more accommodating and cooperative.
On another project, he removed the traffic signals and signs and replaced a traditional four-way intersection with what he called a “traffic square”. The resulting increase in cooperation between motorists, cyclists, and pedestrians led to a dramatic decrease in the collision rate. He often demonstrated the effectiveness of this new intersection by safely walking backwards down the street with his eyes closed.
Keeping the Peltzman Effect in mind may help drivers, city planners, and traffic engineers to more safely negotiate the current driving situation. Drivers who rely on vehicle safety technology and roadway improvements to keep them safe could be forgetting that safety on the roadway is ultimately their own responsibility.