A simulation study of unit exchange spares management of diesel locomotives in the Indian Railways

This paper focuses on modelling and analysis of a repair inventory system of diesel locomotives in the Indian Railways (IR) based on the concept of unit exchange spares (UES). At present, the UES management problem has been solved as a one-time static and deterministic single-echelon problem based on global averages of repair arisings, whereas in reality it is a multi-echelon, multi-indentured repair inventory system in a dynamic environment. A combination of physical system theory (PST) and system dynamics (SD) has been chosen to be an appropriate modelling strategy for the study of the system. While PST provides modelling for the flow in the system, SD provides a methodological support for simulation and policy analysis enabling the study of the dynamic behaviour of the system. A simulation model of a UES remanufacturing inventory system using PST in SD framework has been developed and an empirical study employing a group of ten diesel loco sheds and one remanufacturing workshop has been reported. A number of policy experiments employing the model have been carried out and presented in graphic form to provide a DSS for managers for rationalising the policies for the UES management.