Cost-benefit analysis (CBA) for transport and infrastructure projects serves as a framework for a transparent description of the economic and social effects of the project. CBA information is useful in almost every stage of policy preparation to facilitate decision-making. The benefits of travel time savings are amongst the most important aspects of a CBA for infrastructure. These benefits are however only related to reductions in the average travel time. Studies show that not only reductions in the average travel time but also reductions in travel time variability, or improved travel time reliability, must be considered among the important benefits of infrastructure projects (SACTRA, 1999). It is expected that benefits of improved reliability will be of substantial importance in comparison to benefits of reductions of the average travel time. However, the fact remains that benefits from improved reliability are not included in official national CBA-frameworks for appraisal of infrastructure projects. To take reliability on board of CBA’s is regarded as a major issue amongst economists in Denmark, The Netherlands, Sweden, and the United Kingdom. In the literature is still controversy on how to define reliability and on the methodology that must be used for giving it a value. The research program of AVV on reliability resulted in a reliability indicator that can be used to find monetary values. This paper starts with the description of the organization of the AVV research program (section 2). Then reliability of travel time is addressed (section 3). Subsequently, we describe three methods to measure the value of reliability. We explain why we decide for the standard deviation as an indicator and how it can be applied (section 4 and 5). Finally, we draw conclusions and discuss further research (section 6). (Author/publisher)
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