Chapter 15 Characteristics of transport and travel

Travel is an integral part of all our lives and all potential travellers have a choice about whether and when to undertake a journey, by which mode and at what cost, albeit that on occasions these choices may be limited, for example, the time of the journey to work is generally limited although with some flexibility. In the recent past, it was generally the case that travel demand was predicted and the infrastructure designed to meet that demand. More recently, as it is recognised that there are constraints influencing supply, the focus has been on managing the demand to a level of acceptable infrastructure provision, even though an upward trend in travel demand remains.

An effect of transport improvements is, generally, to reduce journey times and hence costs. This affects how people travel and hence the level of demand. If schemes improve travel conditions this will encourage people to undertake trips they did not make before, to change the time of the trip, change to a different mode, or to travel further to different destinations. It is likely that any change to travel conditions will, in principle, cause a change in demand.