Optimum Proactive Maintenance for Critical Infrastructures Subject to Multiple Degradation and Environmental Shocks

Abstract

Critical infrastructures (e.g. power networks, transport systems, financial services and telecommunication) constitute the backbone of the society. A failure in these systems may result in substantial costs in terms of lost service delivery and emergency maintenance operations. Failures of critical infrastructures mainly occur as a result of various degradation (deterioration) processes in their consisting units as well as due to external shocks arising from surrounding environment. In order to avoid such failures, various proactive maintenance policies, including routine inspection, age (usage)-based replacement, and condition-based maintenance are commonly applied. In this paper, we formulate an optimization framework for proactive maintenance planning of critical infrastructures subjected to stochastic degradation and environmental damages. The infrastructure in our study is composed of multiple identical sub-systems, each exposed to a gradual degradation phenomenon. The environmental shocks are divided into two types of minor (with probability p) and major (with probability 1−p, where 0 ≤ p ≤ 1). A minor shock causes a disruption in system operation without resulting in any failure, while a major shock stops the system and requires a costly replacement. The performance of the proposed maintenance policies, regarding the objective of minimum average long-run maintenance cost per unit time are compared to existing practices of maintenance. Several case studies within the subsea pipeline, marine renewable energy, and the rail transport industries are presented to illustrate the results.