Understanding the driving factors of cost overrun in highway projects in Nigeria: a systems thinking approach

Abba Tahir Mahmud, Stephen Ogunlana, W.T. Hong

Research output: Chapter in Book/Report/Conference proceedingConference contribution


In recent years, cost overrun was one of the most significant concerns for infrastructure development and understanding the triggers of cost overrun is vital in delivering critical infrastructural projects within the contractually agreed budgeted cost. Although, existing studies have focused on identifying and understanding critical risks factors impacting project cost performance, limited efforts have investigated the complex and dynamic interactions that exist among the triggers. Hence, this study adopted a holistic perspective to investigate and
understand the impact of the dynamic interactions of the various triggers on project cost performance based on the philosophy of systems thinking. Based on a data compatible coding framework, qualitative data based on stakeholder interviews was analyzed to identify the contextual key factors and their causal relationships, complemented by textual data from existing literature. Subsequently, causal loop diagram was developed based on the underlying interactions among the key drivers to describe their complex and dynamic nature. The finding shows that the relationship of the cost performance risk factors is reciprocal and looped and thus, captured the dynamics of typical context-based system. The developed conceptual model can be used to identify system improvement points to enhance project performance and form the basis for a formal simulation model.
Original languageEnglish
Title of host publication6th International Project and Construction Management Conference (e-IPCMC2020)
Subtitle of host publicationConference Proceedings
Place of PublicationIstanbul Technical University, Turkey
Publication statusPublished - 12 Nov 2020
Event6th International Project and Construction Management Conference, Istanbul Technical University, Istanbul, Turkey. - Istanbul Technical University, Istanbul, Turkey
Duration: 12 Nov 202014 Nov 2020


Conference6th International Project and Construction Management Conference, Istanbul Technical University, Istanbul, Turkey.
Abbreviated title(e-IPCMC2020)


  • causal loop diagram
  • cost overrun
  • highway projects
  • qualitative data
  • system thinking

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