Chapter 2: The Relationship between Economic Activity and Freight Transport

Traditionally the relation between economic activity and freight transport is used to make forecasts of future aggregate freight flows and volumes. Usually gross domestic product (GDP) is used as an indicator for economic activity in a region or a country. National and international organisations collect data on GDP and also make forecasts of GDP. This explains to some extent the reason for using GDP as indicator for future freight transport.

In this contribution we will show by using stability and co-integration tests that GDP is not the best indicator because its composition changed and is still changing, because some methods to link freight transport to GDP are not suited, and because the link between freight transport and economic activity itself has been changed. There are several reasons for this: the globalisation of the world economy, policies aimed at decoupling freight and economic activity, and changing business behaviour (time based competition, labour vs. transport costs …). This makes reliable long-term aggregate forecasting of freight transport on the basis of GDP very difficult.