Putting context to numbers: a geotechnical risk trajectory to cost overrun extremism

The study investigates the cause of the unusually high cost overruns experienced in highway project delivery in the tropical wetland setting of the Niger Delta region of Nigeria. An empirical profiling of cost overrun research reveals the predominance of mono-method studies, all of which are underlain by positivism. The study argues that such positivist philosophies, although methodologically valid, cannot adequately provide in-depth understanding of the contextual cost overrun drivers in highway organisations. Using a mix of methods, the paper examines the contribution of geotechnical risks to the extreme cost overruns experienced on Niger Delta’s highway projects, and demonstrates the relevance of context in cost overrun research. Adopting a geotechnical narrative, data sourced from 61 highway projects along with 16 interviews conducted with highway agencies in the region is analysed. The results of the analysis identified that poor project governance and procurement practices, have inhibited the competent management of geotechnical risk, creating a propensity for extreme cost overruns on highway projects. The study submits the phenomenon of cost overruns in public infrastructure projects is underlain by a complexity of contextual social constructs, which would have been overlooked in positivists studies. Cost overrun research, therefore, needs to be contextually and numerically anchored.