A Decision Support System for analysing conflicts related to pricing policies implementation Un sistema di supporto alle decisioni per l’analisi dei conflitti derivanti dall’implementazione delle politiche di pricing

In recent years several European cities have introduced pricing policies 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 overall utility maximisation and fails to 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. Moreover, one of the main problems related to pricing policy application is their acceptability among community and/or social categories (such as shopkeepers, residents, commuters, etc.) leading to conflicts and oppositions. In this paper we analyse the effects on optimal fare design when pricing revenues are wholly or partly used for improving public transport. In particular, we formulate a model according to economic theory in a multimodal and multiuser context, where multimodal features are calculated explicitly on the network for each fare configuration. The model is applied on a trial network (built with heterogeneous values of relative accessibility among different traffic zones) and several second-best strategies are analysed with particular attention to the use of pricing revenue. Negli ultimi anni molte città europee hanno introdotto politiche di tariffazione come strumento di gestione della domanda di trasporto, in particolare per ridurre la congestione e riequilibrare la ripartizione modale tra trasporto individuale e collettivo. Infatti, il comportamento degli utenti conduce il sistema ad una condizione di Equilibrio dell’Utente (User Equilibrium) che non corrisponde alla massimizzazione dell’utilità globale e non prende in considerazione i costi esterni. Pertanto, al fine di raggiungere una configurazione efficiente nell’utilizzo dei sistemi di trasporto (indicata in letteratura come Equilibrio del Sistema – System Equilibrium), è necessario imporre una tariffazione sulle strade urbane in modo da massimizzare il surplus sociale. Per numerose ragioni (teoriche, politiche, sociali) è impossibile applicare “tariffe efficienti” (indicate in letteratura come first-best solutions); perciò sulle reti reali bisogna applicare tariffe sub-otti