Abstract
This paper presents a decision support model for evaluating the economic and environmental performance of alternative maintenance strategies for maximising the service life of old railway infrastructure assets. It combines both economic and environmental criteria to assist asset managers in identifying the optimum maintenance option out of several possible alternatives. The paper elaborates the model framework and presents the main steps of the developed methodology, based on Life Cycle Costing and Life Cycle Assessment approaches. The methodology is underpinned by the BS EN 60300-3-3: 2004 standards for life cycle costing and complies with the BS EN ISO14040 standard series on life cycle assessment. The integration of the cost and environmental performances and their trade-off is explored through multicriteria decision analysis to determine the optimum maintenance strategy. A case study using the maintenance plans for a U.K. railway bridge is presented to illustrate the use of the model. A novel time-weighting is introduced into the model's decision analysis to allow evaluation of temporarily delayed emissions.