A review for evidence for induced travel: a pacific motorway case study

The theory of induced travel states that an increase in highway capacity will induce a growth in traffic volumes along that highway. This paper begins with a discussion of the basic definition of induced travel as well as its theoretical background. Various studies published on the effect of increasing highway capacity and its impact on traffic volumes are then critically analysed in terms of the methods used to quantify the effects of induced travel as well as the results and conclusions drawn from these studies. A new case study is then conducted using similar evaluation techniques to those reported in the literature to determine whether the upgrade of the Pacific Highway to the Pacific Motorway has contributed to induced travel along the motorway. Data from various sources was collected and analysed, during the period from 1996 to 2004. This study incorporates two different forms of analysis, each utilising different data sets, in an attempt to determine whether induced travel is present. Each analysis draws the same the conclusion: that induced travel is not present on the Pacific Motorway. A number of issues regarding the completeness of the available data, the simplicity of the models used and the validity of the conclusions are also discussed in the report.