A multimodal multiuser approach for analysing pricing policies in urban contexts

In recent years several European cities have introduced road pricing as a tool for managing transport demand, especially to reduce traffic congestion and rebalance the modal split between private vehicles and mass-transit systems. Indeed, user behaviour brings about a User Equilibrium condition which does not correspond to the overall utility maximisation and does not take account of external costs. Hence, in order to achieve the efficient use of transportation systems (System Equilibrium), tolls can be charged on urban roads so that the social surplus is maximised. For several reasons (theoretical, political, social acceptability) it is impossible to charge 'efficient tolls' (first-best solutions) proposed in the literature; therefore in real networks sub-optimal tolls (second-best solutions) are applied. Road pricing application involves many political and social issues to be solved by policy makers, such as what to do with road pricing revenues. This aspect is analysed in this paper. In particular, we formulate a toll computation model according to economic theory; the model is then applied in a trial network to analyse several second-best strategies (such as cordon and parking pricing) and estimate possible effects of road pricing revenues use on social welfare and fare levels.