Transport choices for urban passengers : measures and models.

The report is the result of a study carried out in 1978 and 1979 on methods to describe and influence modal split. Experts from twelve OECD member countries participated to review the international state-of-the-art in this field which is gaining in prominence due to the economic, environmental and energy constraints of urban transport. The report presents some of the alternative strategies for influencing modal split and describes available measures and some of their possible effects (chapter I). Chapter II presents the results of a survey regarding the aims, measures taken or envisaged to modify modal split, the type of investigations carried out (including data collection), the effects obtained and the achievement of the aims. The survey was carried out on the basis of thirty-two practical examples provided by national delegates. In chapter III a short historical overview of existing urban transport models is given with special emphasis on the modal split models. The chapter deals with the different types such as elasticity models, aggregate (zonal) models and disaggregate models. A critical evaluation of models is given in chapter IV with emphasis on the limitations of the modelling process and the validity of models for prediction. Practical experience of modelling and data requirements are also discussed in this chapter with reference to some of the examples described in chapter II. From considerations of the need for a more comprehensive understanding of urban travel behaviour chapter V examines the future research fields regarding the possible development of modal-split models, also taking into account the subjective factors which govern travellers' selection of transport modes. Items such as interaction between modal split and other components of transport modelling procedures, inertia effects, land use/transport interactions and behavioural variables are also discussed. Chapter vi presents the conclusions and recommendations of the group regarding improvement of modal-split models and their ability to describe the effects of certain measures which influence the relative use of transport modes. (a)