Keeping Passenger Surveys Up to Date: A Fuzzy Approach

The knowledge of travel demand is an essential prerequisite for analyzing and planning transport supply. Obtaining travel-demand data for a transit system requires passenger surveys that combine counts and interviews. Passenger surveys have two unpleasant characteristics: they are expensive, and the results of such studies tend to lose their validity fairly rapidly. For these reasons, the development of techniques that reduce survey costs and keep demand matrices up to date is gaining increasing interest. Details of a technique for computer-aided processing of passenger surveys are given, and a method for continuous updating of demand matrices is presented. Because traffic surveys represent only a snapshot situation, the proposed updating method employs a fuzzy approach to consider that traffic volumes vary within a certain bandwidth.