Accounting for network effects in railway asset management

System-level infrastructure management involves determining optimal maintenance, rehabilitation, and reconstruction activities for a system of facilities over a planning horizon to maximize the level of service subject to system constraints. In railway networks, different types of facilities (such as tracks, and bridges) comprise the system, and maintenance of one facility may affect the maintenance of other facilities, both economically and functionally. Therefore, when developing an asset management system for railway networks, it is essential to take into account heterogeneity and interdependency in the network. In this paper, a two-stage, bottom-up methodology is formulated to capture these interdependencies and heterogeneities in railroad infrastructure management. Numerical experiments are presented to examine the effects of economic and functional interdependencies on network optimization and to demonstrate the validity of the proposed model. The results show that accounting for heterogeneity and interdependencies at the system level can greatly influence the choice of activities and the estimated life-cycle cost.