Travel Demand Growth: Research on Longer-Term Issues. The Potential Contribution of Trip Planning Systems

INTRODUCTION

1.1 The growth in demand for travel

Over the 20 years hm 1965, National Travel Survey (NTS) data shows a 61% growth in total person - km of travel. More detailed analysis suggests that this is made up roughly as follows:-

due to increased population 4%

due to more journeys 22%

due to longer journeys 35%

This implies that around 60% of the growth in travel has been due to people travelling further, rather than making more journeys.

It is interesting to note, too, that the same phenomenon occurs even in the most congested areas. Between 1975 and 1985, NTS shows an 11% growth in person -km by London residents, at a time when population fell by 5%. In this case, the growth is made up roughly as follows:-

due to lost population -5%

due to more journeys 4%

due to longer journeys 12%

It is of course difficult to estimate the extent to which future growth in travel will be generated by longer journeys. The NRTF, which predicts a growth in car-km of between 120% and 180% between 1985 and 2025, is not based on a procedure which enables the effects of journey making and journey length to be separated. However, it is worth noting that if the same pattern were to exist at a national level in future, the predicted growth in car travel due to longer journeys could be equivalent to between 75% and 100% of today's car travel. It seems appropriate to ask whether it is a wise use of scarce resources to provide the infrastructure and energy needed to enable people to carry out their activities further from home. (Continues...)