What effect do Queensland's major road infrastructure projects have on traffic volumes and growth rates?

This paper investigates the effect that major road infrastructure projects have on the traffic volumes and traffic growth rates on sections of the network directly affected by the project. The paper also considers whether such changes in traffic volume, possibly induced traffic, influences the economic viability of such major projects. A sample of major projects located along Queensland highways and motorways have been used in this study. Traffic volumes before and after the completion of the project are compared to determine if traffic volumes and/or traffic growth rates are influenced by the project. The types of major road infrastructure projects considered in the study are town bypasses, deviations, and major road widening projects. Major projects are compared based on a number of factors such as project type, volume capacity ratio at the time of construction, and the extent of the increase in capacity. These comparisons have been used to determine the extent project and network related factors influence changes to traffic volumes and growth rates. The results of the study aim to determine the extent that induced traffic influences the benefit streams for major projects. Two hypothetical examples have been included in the paper, one example assumes that traffic growth is unaffected by the project and the other example assumes traffic growth follows a pattern similar to the case studies investigated. This paper will discuss the significance of the impact induced traffic has on the economic viability of projects and the types of projects that are more likely to have their benefit streams eroded by induced traffic.