Methodological advances in modelling and forecasting car ownership in Great Britain.

This paper presents a summary of the findings of a study aimed at improving the car ownership forecasting methodology employed by the UK Government's Department of Transport, Local Government and the Regions. The work centres on two key areas. In the first instance, the structure of the existing national ownership model is improved to incorporate a range of policy sensitive variables, and the model calibration process updated to take account of new estimation techniques. Secondly, a new forecasting methodology is introduced to generate local forecasts of ownership across Great Britain. This work forms part of an ongoing process of incremental change to the National Transport Model, however, the views expressed in this paper are those of the author and not necessarily those of the Department. To place this work in context, an outline of the car ownership forecasting methodology used to produce the National Road Traffic Forecasts-1997 is given in Section 2. Section 3 describes the new structure of the models and estimation process. Section 4 provides a description of the new forecasting methodology. Section 5 gives an explanation of the final adjustments to the model and a sample of the accuracy of the forecasts. Finally Section 6 makes recommendations for further work.