A two-step data analysis method - mathematical model for locating intermediate facilities and routing garbage trucks (in Persian)

With population growth and rising human density in residential areas, the volume of waste generated continues to increase day by day, while the safe removal of such waste from living environments remains essential. At the same time, the processing and recycling of discarded materials has become a fixed element of waste management systems, completing the end-to-end chain. The issue is therefore of significant contemporary importance, and managers in this domain must give it due attention. Against this backdrop, this paper addresses the problem of locating intermediate facilities and routing waste collection trucks using a two-step approach that combines Data Envelopment Analysis (DEA) with a multi-objective mathematical model. In the first step, DEA is used to select the intermediate facilities. In the second step, a multi-objective mathematical model determines the routing decisions for the waste collection trucks. Demand is treated as uncertain, and a robust optimisation approach is adopted to address this uncertainty. In addition to economic objectives, environmental considerations are incorporated as a further objective in the model, and goal programming is used to solve the resulting multi-objective formulation. The proposed two-step method is evaluated through a case study in Region 8 of Tehran, from which several important managerial insights are derived.