System theory based hazard analysis for construction site safety: A case study from Cameroon

Introduction: Construction sites are known for its complex environments where many unsafe acts and/or unsafe conditions exist. Traditional risk analysis methods, such as Probabilistic Risk Analysis (PRA) deal with linear systems or component failures. These traditional techniques are not efficient to analyze nonlinear or complex systems such as construction sites. Method: This study applied a system theory approach to a construction project risk assessment. We used a System-Theoretical Process Analysis (STPA) based on System-Theoretic Accident Model and Processes (STAMP). Data were collected in different stages. Firstly, literatures from various journal papers, articles, thesis, website and the Electricity Development Corporation of Cameroon's (EDC) risk register were reviewed. Secondly, a case study was carried out to check the applicability of system safety to a construction project where PRA was initially used by the project team. Questionnaires were conducted on five selected project team members to get their point of view on the application of STPA. Result: The main contribution of this approach was that by simulating more scenarios, it revealed some systematic risks that were not detected with the PRA approach such as: lack of support from the EDC stakeholders; loss of quality, security and safety when using subcontractors; and unsafe control actions by the risk manager. Conclusion: To cope with the complexity of construction projects, the STPA approach seems to produce higher quality results compared to the PRA approach since its prime aim is to simulate possible scenarios.