In 1989, a two-year multidisciplinary study of the problems of older drivers was initiated. The study was conducted by a team of researchers from the areas of traffic engineering, gerontology, and driver education. The objective of the research was to develop and evaluate strategies for improving the safety of older drivers. During the first year, the problems of older drivers were examined and countermeasures were designed to address these problems. The countermeasures designed were: physical therapy, perceptual therapy, driver education, and engineering countermeasures which consisted of the application of signs, pavement markings, and traffic signal displays to address the problems of older drivers with left-turn and right-turn manoeuvres at signalised intersections and approaches to unsignalised intersections. In the second year, the countermeasures were evaluated by measuring their effects on the driving performance of older drivers. The procedures and results of the second year are presented in this report. A total of 105 older drivers between the ages 65 and 88 years were used to evaluate the effects of the countermeasures on the driving performance of older drivers. The subjects were randomly assigned to six experimental groups which received different countermeasures. The on-road driving performance of the subjects was measured using the driver-performance-measurement technique developed at Michigan State University. All of the countermeasures significantly improved the driving performance of older drivers. Combining driver education with physical or perceptual therapy tended to increase the improvement in driving performance, but none of the increases were statistically significant. Likewise, the engineering countermeasures did not add significantly to the improvement that was achieved by the other countermeasures. The combination of perceptual therapy and driver education provided the greatest improvement followed by the combinations of engineering countermeasures with driver education and either physical or perceptual therapy. However, there were no statistically significant differences among the improvements provided by the countermeasures either individually or in combination. The average improvement provided was 7.9%. Physical therapy was more cost-effective than perceptual therapy or driver education. The engineering countermeasures were more cost-effective than the other countermeasures on high-volume roadways, but not on low-volume roadways. (A)
Abstract