Demographic Change and Future Transport Demand: An Analysis of the British Situation 1989-2006

INTRODUCTION

The planning of transport infrastructure requires as one ingredient sets of forecasts of transport demand. One of the factors that influences transport demand is the composition of the population in terms of person types, with considerable variation in trip making and trip distances between persons by age, sex, economic position, car availability and income (Siu et a1 1994). Normally, attention is paid to the way trip rates for each person category are changing as a result of income or car availability changes. However; the irge and sex structure of the population is also changing and may have influence on future trip making. Also of potential importance is the redistribution of the population over time, predominantly in the direction of lower density areas, which can have very different model mixes from higher density areas.

This paper describes work that attempts to link conventional category analysis based trip forecasting with knowledge of the changing demographic and geographic make-up of the British population. This should, in principle, be an easy task. Trip rates and trip mileages can be computed from one or more National Travel Surveys (NTS) for a highly diagnostic person classification. These trip rates are then trended or a scenario developed, and the forecast trip rates or mileages applied to the forecast population in each category to yield forecasts of the number of trips to be expected in the future, under the assumptions used in the two component forecasts. The 1985/86 NTS dataset is used in this study.

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