ROUTE FAMILIARITY IN ROAD SAFETY: SPEED CHOICE AND RISK PERCEPTION BASED ON A ON-ROAD STUDY

Differences in driving behavior due to the presence of users familiar (or unfamiliar) with the road are considered in the Highway Capacity Manual (HCM) procedure used to evaluate the level of service of Freeways and Highways. However, although considered, the matter is largely unexplored: there is a lack of theoretical foundations and data on determining the impact of route familiarity on accident rates, speed choice and risk perception. On the other hand, some literature studies confirm that route familiarity is influential on driving behavior, encouraging research in this sense. This paper reports the results of a test carried out on a two lane rural road in the District of Bari in Puglia Region (Italy) over six days of testing, in order to find relationships between route familiarity, speed choice and risk perception. In particular, drivers’ perception of high, medium and low speeds is compared with the speed chosen freely, in order to test users’ unconscious tendencies in judging speed and safety-related risk. The main findings are that both speed choice and risk perception seem to be affected by route familiarity: speed increases and risk is underestimated with the repetition of travel on the same route. This effect is more evident in road sections characterized by a greater number of degrees of freedom in speed choice.