Causal model for management of subcontractors in waste minimization

This study presents a causal model to explain the dynamic construction waste generation behaviour exhibited by subcontractors in Singapore and how waste can be minimized. Based on causal methodology, the Construction Waste Minimization model was constructed using Supply Chain Management and Management Control concepts. From these concepts, eight main strategies and other factors for main contractors to manage subcontractors in waste minimization were identified. The model was tested in two ways. Firstly, a postal questionnaire survey of contractors and subcontractors in Singapore was undertaken to check the validity of the variables in the model. Secondly, three in-depth case studies were conducted to confirm the causal loops in the model. The survey results and case study findings confirm that the model is valid and the case studies corroborate the model's practical application. It is recommended that main contractors use this model to manage subcontractors in waste minimization aspect.