Davide Vannoni University of Torino and Collegio Carlo Alberto   Corso Unione Sovietica 218 bis Corso Unione Sovietica 218 bis torino, 10134 italy   vannoni@econ.unito.it   web.econ.unito.it/vannoni/           JEL Areas: L0 : Industrial Organization: General L9 : Industry Studies: Transportation and Utilities: General