Modeling of ERTMS Level 2 as an SoS and Evaluation of its Dependability Parameters Using Statecharts

In this paper, we consider the European Rail Traffic Management System (ERTMS) as a System-of-Systems (SoS) and propose modeling it using Unified Modeling Language statecharts. We define the performance evaluation of the SoS in terms of dependability parameters and average time spent in each state (working state, degraded state, and failed state). The originality of this work lies in the approach that considers ERTMS Level 2 as an SoS and seeks to evaluate its dependability parameters by considering the unavailability of the whole SoS as an emergent property. In addition, human factors, network failures, Common-Cause Failures (CCFs), and imprecise failure and repair rates are taken into account in the proposed model.