Increasing attention has recently been paid to the governance and evaluation of what have become known as ‘megaprojects’ (e.g. Flyvbjerg et al., 2003; Flyvbjerg, 2007; 2011), i.e. ‘large-scale, complex infrastructure projects usually commissioned by governments and delivered through partnerships between public and private organisations, with multiple partners, high uncertainties, and considerable political stakes’ (van Marrewijk et al., 2008: 591).2 Typical examples include infrastructure construction projects such as motorways, tunnels, bridges, railways or ports, which frequently “respond to global competition among cities for investments, knowledge workers, tourists and prestige” (Bornstein, 2007), and are expected to deliver multiple socioeconomic benefits to the society. A number of characteristics specific to megaprojects render their governance and evaluation particularly challenging. These include in particular: the exceptionally large budgets, and hence considerable economic and political interests involved; considerable temporal and spatial scales; continuous evolution and dynamism – also concerning project governance and the institutional framework; and sharp normative disagreements among parties involved, at different levels of governance. Further challenges arise from the lack of precedents, i.e. similar earlier projects, which would help provide a basis for evaluation; the complex causal relationships between governance measures and policy outcomes; and the high degree of scientific, political and institutional uncertainties involved (e.g. Altshuler and Luberoff, 2003; Flyvbjerg, 2007; 2011; Flyvbjerg et al., 2003; Flyvbjerg and Priemus, 2007; OMEGA, 2012).