A dynamic model to assess the role of site supervision systems in the safety performance of construction projects

Although prior research has examined the influence of site supervision on construction safety, a comprehensive systems-level perspective incorporating interdependent relationships among key variables has yet to be fully investigated. In particular, the intervariable mechanisms by which owners impact contractor safety behaviors require further elucidation through a system dynamics (SD) approach. A primary objective of this study is to identify the feedback mechanisms that affect the safety performance of a project as a result of the site supervision systems using SD. The identification of relevant safety variables and the creation of a conceptual causal loop diagram incorporating key variables facilitate the development of corrective actions. After creating a qualitative SD model based on the identified safety variables, the Delphi technique is employed for validation. Lastly, a portion of the validated conceptual model is selected for quantitative analysis. The simulation model is validated through behavior reproduction and sensitivity analysis tests. The results indicate the accurate performance of the quantitative model in capturing the system's behavior. For instance, it suggests that the owner's safety role is a root cause of accidents in construction projects, and owners can influence the safety performance of projects through contractors. The findings revealed an insignificant relationship between changes in the number of accidents and the frequency of owner's representative site visits. Moreover, the quantitative SD model shows that schedule delays should be considered in planning for safety performance improvement in addition to effective safety actions. Practitioners may use the SD model in three ways: detecting the safety outcome during the project, assessing impacts of various model variables on safety outcome, and creating new policies or corrective actions in response to project changes. This paper contributes to the understanding of how site supervision systems impact safety performance in construction projects, providing practitioners with a valuable tool to enhance safety outcomes.