The role of transport supply in the acceptability of pollution charge extension. The case of Milan

Milan is one of the few cities in Europe where a congestion charge is in place. It was experimentally introduced at the beginning of 2008 as a pollution charge to enter the central area of Milan. During 2011, to confirm it and also to extend its scope, a city-wide referendum took place. Referendum results largely supported the extension. While we know well the economic rationale and the potential effects of such policies, the issue of acceptability is still quite unexplored and usually studied with limited interview campaigns, focus groups or theoretical assumptions. This referendum is an interesting occasion to study the real motivations of the acceptability of road pricing experiences in a consolidated context. This paper studies the determinants of the highly positive vote in favour of the extension of the former pollution charge into a congestion charge scheme. The scale of analysis is the aggregate result of the referendum at the neighbourhood level. The variables studied are the ideological orientation, some socio-economic variables, and the distance from the city centre. In contrast to the majority of existing literature, we also include in the analysis the effect of transport supply and previous mobility patterns, in order to verify if they were crucial to the voters’ acceptance of a road charge.