This thesis focuses on the availability estimation by simulation, availability allocation and resilience assessment for railway systems.
Firstly, a brief background of the railway has been given including history, infrastructure and operation, as well as its relation with RAMS engineering. Also, the concepts of availability and punctuality are introduced with formulas and requirements. Besides, a classic definition of resilience is presented and a definite integral method for resilience assessment is proposed. The main approach to determine availability in this thesis, simulation, is described exhaustively in the following chapter.
Then, the overall availability of railway systems in different scenarios is estimated by MATLAB (Version R2018b) simulation. It is proven that the availability performance can fulfill the requirements, under certain assumptions and omission. The discussion of results reveals the proportion of delay reasons including signaling system failures, unexpected dwell time and cascades. Also, the average availability-time diagram of the whole journey is estimated to determine the critical time.
Later, availability allocation is done for the signaling system to reach expected availability. Two allocation methods are chosen. The management implication is discussed based on the results. Meanwhile, a new average availability-time diagram is generated with allocated overall repair rate is generated to present the influences of repair rate upon availability performance and critical time.
In the last part, the proposed definite integral method is applied to prove its applicability for resilience assessment. Several scenarios are simulated and the reasons regarding the differences in resilience performance are discussed as well as the impact of repair rate.