How to avoid unrealistic appraisal results? A concept to reflect the occurrence of risk in the appraisal of transport infrastructure projects

Planning, constructing, financing and operating transport infrastructure involves a wide range of different risks. This poses a challenge for the appraisal of transport infrastructure projects. The current paper addresses this challenge by elaborating on a concept that considers the issue of risk by transport infrastructure evaluation concepts, on the basis of already applied methodologies. The paper begins by substantiating the pattern of ‘risk’ in transport infrastructure planning. Subsequently, five basic methodologies that incorporate the issue of risk in transport project appraisal are briefly presented: sensitivity analysis, scenario analysis, Monte Carlo Simulation, Quantified Optimism Bias and qualitative approaches. For each methodology, real-world applications of infrastructure appraisal in individual countries, regions or supranational organizations are presented. After providing a synoptic overview of these methodologies, a concept is presented that reflects the occurrence of risk in the assessment of transport infrastructure projects.