Le coût économique du report modal vers le tramway

The modal shift of car users towards public transport is a key objective of most investment projects in tramways networks. The cost-benefit analysis of these projects poses many conceptual and practical problems, and work is underway in various institutions to improve these methods. If taking into account the effects of tramways projects on urban landscape or on the quality of life of urban residents poses formidable conceptual problems, those raised by taking into account the effects of modal shift seem much more affordable. We think we have identified two common errors in the economic appraisals of tramway projects: (i) the double counting of some benefits derived from reducing car use, especially on car operating costs and on parking costs, and (ii) the ignorance of the economic cost of the forsaken tax revenues from car use. We also tried to give orders of magnitude for these variables to assess their impact on the results of the cost-benefit analysis of these projects. These estimates show that modal shift is a net gain for the motorists who switched to tramway use but that it has a largely negative balance for the rest of the community. Overall the net benefit of modal shift is much lower than generally presumed.