OBSERVED VEHICLE SPEED AND DRIVERS PERCEIVED SPEED OF OTHERS

Attempts to model driver behaviour have traditionally included three b asic elements: the driver, the vehicle, and the traffic environment. N o account has been taken of a fourth element, the social environment i n traffic. In the present paper, based on data from Denmark and Sweden , drivers' attitudes towards speeding and influences from other road u sers on drivers' speed choice were investigated, Recorded vehicle spee ds (N = 483) were compared to drivers' responses to questions concerni ng their speed choice. The questionnaires were based partly on the The ory of Reasoned Action suggested by Ajzen and Fishbein (1980) with que stions tapping the social traffic environment substituting for the sub jective norm in the model. The results indicated that a model includin g attitudes as well as perceptions about other drivers' behaviour coul d explain about 15% of the the variation in observed speed. More than 50% of the drivers exceeded the speed limit and a majority of them ove restimated the speed of other drivers. Theoretical and practical impli cations of the results are discussed.