Civil infrastructure system maintenance planning is to determine which facility should be repaired,when and how maintenance should be carried out,and what treatment should be used under budget and other resource constraints.In the existing literature,various simulation and optimization models have been developed to help select the optimal maintenance plan.However,the developed models overlooked the deterioration propagation between adjacent connected facilities of the network infrastructure system.For instance,a facility receiving zero maintenance or having a failure of maintenance treatment affects not only the condition of itself,but also the deterioration rate of its neighboring facilities.This raises the call for taking the deterioration propagation into consideration when developing optimization models and capture to which extent it can affect the optimal maintenance plan.Therefore,in this paper,an infrastructure maintenance planning model considering the deterioration propagation between facilities is formulated as a mixed integer linear programming problem.A heuristic algorithm was proposed to solve the problem efficiently.Example networks were tested for the performance comparison between CPLEX and the heuristic algorithm.The proposed model performs better than models without the deterioration propagation.