“…Gómez Ibáňez (2003), for example, widely discusses four main regulatory "models", namely public ownership, franchise allocation, discretionary regulation, and private ownership in conjunction with liberalisation and regulation of access, prices, and quality. Why public authorities adopt any particular regulatory model and what are the relative strengths and weaknesses of alternative regulatory systems have been largely examined by several works (Amato and Conti, 2005;Baumol, 1982;Beecher, 2001;Bishop and Walker, 1999;Christoffersen and Paldam, 2003;Demsetz, 1968;Ferris, 1986;Ferris and Graddy, 1988;Finger and Allouche, 2003;Groom et al, 2006;Warner, 2004, 2007;Hirsch, 1995;Kay and Thompson, 1986;Littlechild, 1986;Lobina and Hall, 2003;Massarutto, 2007;McGuire et al, 1987;Megginson and Netter, 2002;Merrett, 1997;Miranda, 1994;Ogus, 1994;Rees, 1998;Schmalensee, 1979;Tenbüken, 2006;Vickers and Yarrow, 1998;Warner and Hebdon, 2001;Williamson, 1976). Some authors hold that there may be no single "best way" to regulate infrastructure (Glachant, 2002;Goldberg, 1976), while others argue that the design of regulatory systems should follow "standard prescriptions" (Joskow, 1996(Joskow, , 1997 that suggest that the potentially competitive activities in infrastructure industries should be disentangled (unbundled) from those characterised by natural monopoly conditions and that regulations should be tailored in order to facilitate competition in the former activities to restrain rent-seeking behaviour in the latter ones.…”