A Stylised Cost–Benefit Model for the Choice Between Bus and Light Rail

In the last 20 years light rail schemes have been introduced in many European cities. Previous studies indicate the benefits of these schemes seem to have been sometimes overestimated. This paper tries to understand the circumstances in which light rail schemes can be truly worthwhile compared to bus systems, by developing a simplified cost-benefit model. The proposed methodology is suitable for the early appraisal of any new urban light rail line and can be used specifically for comparative purposes. The paper finishes with some investment threshold nomograms and an application expost to a new tram line built in Italy.