Service system design for managing interruption risks: A backup-service risk-mitigation strategy.

•This paper considers the design of a service system with interruption risks.•The backup-service strategy is used to mitigate interruption risks.•Risk mitigation is enhanced by optimizing location, allocation, and service capacities.•The problem is formulated as an integer non-linear program.•A Lagrangian-relaxation algorithm is developed to solve large-size problem instances.