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. This is in view of the extensive literature supporting the link between geology, the lack of geotechnical best practices and cost overruns. An empirical profiling of cost overrun research further reveals the predominance of mono-method studies based on survey methods, correlative analysis and archival data modelling techniques, all of which are underlain by positivism. The study argues that such positivist philosophies, although methodologically valid, cannot adequately explain and provide in-depth understanding of the contextual cost overrun drivers in highway organisations., Using a robust and thoughtfully designed mix of methods, the paper examines the contribution of geotechnical risks to cost overruns experienced in highway project, and demonstrates the relevance of context in cost overrun research. Cost overrun data from documentary sources for 61 completed highway projects in the Niger Delta are gathered and analysed, revealing an average value of 216%, with extreme cases, ranging up to 1925% of budgeted cost. To uncover the intrinsic contextual drivers, 16 interviews were conducted with participants from the three highway agencies in the region, responsible for the execution of the sampled highway projects. Adopting a geotechnical narrative, the data is thematically analysed, deductively and inductively. The results of the analysis identified that poor project governance, management and procurement practices, have inhibited the competent management of geotechnical risk, creating a propensity for extreme cost overruns on the 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. Keywords: Context, Cost overruns, Highway projects, Mixed methods, Social Construct