The determinants of cost deviations and overruns in transport projects, an endogenous models approach

Cost deviations and overruns are a recurrent topic in the transport infrastructure literature. Even though there is a general trend towards a more frequent occurrence of overruns the main determinants of such phenomena are still not consensual. This paper analyses a dataset of 1091 transport projects developed by the Portuguese government (central, regional, and local) between 1980 and 2012. The methodology builds on existing approaches but provides a more ambitious (and innovate) approach towards the incorporation of exogenous determinants, examples being political, legal and regulatory, and economic ones. The analysis suggests that these exogenous variables that have been under-valuated in the existing literature, and that they do, indeed, play a relevant role in understanding cost deviations.