Modeling of railway systeM Maintenance and availability by Means of colored Petri nets Modelowanie utrzyMania ruchu i gotowości systeMu kolejowego za PoMocą kolorowych sieci Petriego

Maintenance plays an essential role in a system’s life cycle. At the system level, the maintenance influences the reliability and availability of the system [3]. Achieving a high maintainability in the railway system requires a proper maintenance strategy. More maintenance means more life-cycle cost, while it may not lead to a dramatical improvement in the reliability. Hence, the performance of the strategy should be evaluated before it is put into the practical application. Given that the enormous number of system components and maintainable items, it is a complex task to carry the analysis of railway system maintenance and availability. Railway system includes different subsystems, and the system structure will influence the overall system availability and performance. When managers plan a maintenance strategy, they have to take the system architecture into account. As in a free market, the optimal maintenance strategy can not only guarantee the availability of railway system but also have the best economic benefits. For the system maintenance and availability analysis, there are mathematical formulating and model-based analysis approaches. Garmabaki et al. presented the Multi-Attribute Utility Theory (MAUT), which used multiple objective functions to evaluate the cost and reliability of the maintenance optimization [5]. A gamma deterioration process was proposed by Meier-Hirmer et al., and it was applied to analyze the track maintenance [10]. Furthermore, the Maintenance Engineering Department of French National Railway Company (SNCF) introduced a formal method to estimate the maintenance strategy [1]. In publication [13], an application of stochastic Petri nets was presented to analyze the signal maintenance in France. All in all, comparing with the mathematical formulating approach, the model-based analysis can provide a more structured overview of the system. Additionally, it is much easier to read than the pure mathematical calculation [14]. Based on the existing database, some maintenance parameters are available. In order to evaluate the efficiency of the maintenance strategy, simulation-based analysis can be used to implement this task. Formalization & modeling can efficiently and cost-efficiently represent a real-world system. The system security analysis based on modeling is widely used in different research areas [17]. Stochastic-process techniques can be used to optimize the maintenance policies [4]. Due to the different overall system structure and Song H, ScHnieder e. Modeling of railway system maintenance and availability by means of colored Petri nets. eksploatacja i niezawodnosc – Maintenance and reliability 2018; 20 (2): 236–243, http://dx.doi.org/10.17531/ein.2018.2.08.