THE PRIMARY DESTINATION TOUR APPROACH TO MODELLING TRIP CHAINS --TRANSPORTATION PLANNING METHODS. PROCEEDINGS OF SEMINAR M HELD AT THE PTRC SUMMER ANNUAL MEETING, SUSSEX UNIVERSITY, ENGLAND, JULY 14-17, 1986. VOLUME P282

Recent research on the issues of trip chaining and travel time budgets has highlighted the interdependence of the trips made by an individual during a given day and drawn attention to the shortcomings of travel demand models that assume independence among the trips. An improved alternative strategy is to group trips into round-journey tours, serving particular out-of-home activities, then to apply demand choice models to these tours. This approach has the merit of preserving the focus on activities and emphasising the nature of travel as a derived demand. However, there is an immediate difficulty in respect of the number of possible distinct tours that can be considered. If the number and purposes of the activities in the chain are incorporated, together with the order in which the activities may be visited, a potentially unmanageable number of possibilities might be obtained. A practical and intuitive solution is to identify one activity as "primary" for the tour, and to classify the tours on the basis of their primary destination purposes. From this starting point, more detailed representations of travel to secondary destinations can be modelled conditional on the primary destination chosen. The problem of the identification of the primary destination is addressed and comparisons drawn of the performance of compensatory and non-compensatory models in representing self-assessed destination importance. This paper draws on experience in two major modelling studies in the Netherlands to reach conclusions about the practicality and robustness of the approach in comparison with other methods of representing trip-chaining behaviour. Modelling methods are described for primary destinations and for secondary destinations.(a) for the covering abstract of the seminar see IRRD 812674.