Three Field Studies of Driver Speed Adaptation

Abstract

Three field studies of driver speeds were conducted to test the speed adaptation phenomenon and to define the practical implications of its effect. Sites were selected in which the speeds of vehicles previously exposed to high-speed conditions could be contrasted with speeds of vehicles not previously exposed to high speeds. The following conclusions were drawn from the results of this study: Conditions specific to a traffic site, such as legal speed limits, traffic density, and cross-street activity, determine the extent of speed adaptation. Speed perpetuation does not account for observed speed differences between speed-adapted and non-speed-adapted vehicles. The effects observed in the present study were significant but lower than in previous studies, possibly because of overall lower vehicle speeds. These findings indicate that proposals to increase speeds on rural interstates are likely to result in higher speeds on other, connecting roads as well.