Application field and optimal co-ordination of fixed interval timetable services in passenger interchanges

The adoption of fixed interval timetables generally simplifies the building of the timetables. It allows also a better use of infrastructures, vehicles and personnel. The main objectives of this study consist of the derivation of general laws and methodologies from the analysis of real situations concerning the passenger interchanges served by at least one fixed interval service. The parameter to be minimised is the waiting time for the passengers. The investigation interested a total of 25 interchanges in 4 European countries (Italy, Switzerland, Finland and Austria) including railway regional and metro services, tram and bus lines. On the basis of this variegated set of situations it was derived and tuned an original widespread model capable to: a) define the limits of convenience for the adoption of fixed interval or “by appointment” timetables; b) outline the programming of the optimum timetable in order to reduce the passenger waiting times for the correspondences; c) consider the consequences of the ordinary timetable perturbations by means of a probabilistic approach based on theoretical distributions of delays.