Transport systems assessment

Introduction: This chapter considers the challenges facing national transport infrastructure systems now and in the future. It introduces the wide range of issues which are currently facing such systems around the world, before considering how future changes in demand for such systems can be modelled, based on a case study of Britain. The development of a new model of Britain's transport system is described, followed by a discussion of the results produced by this model when used to predict the impact of a set of potential future transport strategies under a range of external conditions. Finally, the policy implications of these results are discussed along with the potential impacts of interdependencies with other infrastructure systems. For the purposes of this chapter, national transport infrastructure systems are defined as comprising the road and rail networks along with all major airports and seaports. While the vehicles which operate on this infrastructure are not usually considered to form part of the infrastructure system, they are nonetheless crucial, as changes in factors such as vehicle efficiency and fuels will be key in determining levels of impacts such as carbon emissions, as well as the demands on other sectors, particularly energy. A significant proportion of transport infrastructure currently experiences congestion for at least part of the day, with the peaks caused by large numbers of people travelling to school and work with short arrival windows placing particular pressure on capacity. A key challenge for transport planners is therefore finding ways to address this congestion and its detrimental effects on the economy and the environment. This is linked to the question of whether it is possible to accommodate existing and predicted traffic on the existing infrastructure system by increasing the efficiency of its operation, or whether the construction of additional infrastructure is required. It seems inevitable that at least some additional construction will be necessary to address key pinch points, but the latent traffic phenomenon means that this will not necessarily reduce congestion (Goodwin, 1996). While growth in the demand for travel by some modes (notably the car) has been levelling off in recent years (see Figure 5.1), the substantial population growth predicted in coming decades means that total travel demand will almost certainly increase even if travel per person is static or declining.