A Model to Select a Portfolio of Multiple Spare Parts for a Public Bus Transport Service Using NSGA II

This study proposes a model for managing spare parts in urban passenger bus transport companies so as to support maintenance planning decisions. Spare parts play a significant role in the assets of these companies because inappropriate management of these inventories can cause significant losses to the business. A multi-objective model based on NSGA-II is developed to aid the management of spare parts in corrective maintenance. A multiple item portfolio approach is defined instead of a traditional single item approach. As a typical portfolio problem, a portfolio of multiple spare parts combines "n" items while competing for the same resources. Two criteria were considered: the level of service and the total acquisition cost. An adaptation of non-dominated sorting genetic algorithm II (NSGA II) was used to solve the problem. The model was tested in an urban passenger bus transport company in the city of Natal, Brazil.