Assessing the causes of project overruns in tunnel construction projects in Pakistan

Tunnel construction is considered a bottleneck point in mega construction projects because of higher associated risks and uncertainties. This study is an attempt to identify and rank the causes project overruns in tunnel construction projects in Pakistan and propose a mitigation strategy to minimize their effects. For the given purpose, a total of 32 key causes were obtained from the literature and discussion with a team of experts and practitioners. A web-based questionnaire survey was used for data collection. About 55 complete responses were received from the practitioners working as clients, consultants, and contractors in Pakistan. The identified causes were ranked using frequency, severity, and relative importance indexes. The most important causes were found to be inexperienced and incompetent contractors, ignoring consultants' instructions by contractors, inadequate project estimates, delay in issuance of funds to the contractors, and low bids. This study can be employed for controlling the leading causes of overruns in tunnel construction projects. Moreover, it can serve as a guide in further investigation of the causes of project overruns in tunneling in different countries.