Cost overruns experienced in transportation infrastructure projects continues to remain an issue of wide scholarly interest throughout the developed and developing world. Adopting a geotechnical trajectory, this research investigates the cause of unusually high cost overruns experienced in highway projects, executed in the tropical wetland setting of the Niger Delta region of Nigeria. Using the case study research strategy, archival data is sourced along with sixteen interviews conducted within the three highway agencies responsible for infrastructure project delivery in the region. The qualitative data gathered was comprehensively analysed using deductive-inductive thematic analysis. The results of the analysis identified latent triggers such as non-adherence to geotechnical best practices, amidst a wide array of unanticipated social constructs, which festered in the practises of the highway agencies. The interplay of the emergent social constructs with the fundamental geotechnical triggers is cognitively mapped out, relaying the intricate web of the contextual dynamics, driving the unusually high level of cost overruns experienced in highway project delivery in the Niger Delta. The study submits that the phenomenon of cost overruns in highway projects is multi-hydra headed, driven by a complexity of technical and social variables, contextually specific to the practices of highway organisations.
Keywords: Cognitive Mapping, Highway Organisations: Project Delivery; Cost Overruns