The implementation of railroad PTC systems in the United States has been hindered by the lack of a suitable regulatory environment. Understanding implementation efforts have often been further hindered by lack of a clear understanding of the basic PTC architecture and functionality. This paper summarizes the recent regulatory change that supports the implementation of PTC in the United States. The final regulation poses its own challenge, especially when a government agency and a regulated industry need to make a transition from prescriptive-based to performance-based standards. However, the new regulations provide positive benefits over previous prescriptive approaches in implementing PTC.This paper describes basic PTC architectures and functionality being adopted in the railroad environment, and closes by highlighting two different implementations of the same basic PTC architecture.
Positive Train Control (PTC) systems can eliminate the consequences of collision or derailment. However, prior to the full-scale deployment of these systems, the Federal Government must conduct a regulatory review and approve the risk analysis of the PTC system performance. The objective of this review is to ensure that the operating environment after installation of the PTC system is at least as safe as the operating environment before the system installation. This paper is intended to provide researchers an understanding of PTC, the reason for its use, the regulatory requirements for the required comparative risk analysis of the PTC system, the critical failure modes that the comparative analysis must address, and future work that would facilitate the risk assessment process.
Misuse Cases are recent UML constructs that can be used to specify the mal-acts against which a requirements engineer seeks guarantees from the designer. However, Misuse Cases have not been formally adopted in UML, and therefore lack a formal metamodel. This paper proposes a meta-model that covers graphical, textual and OCL models for Misuse Cases that augments the existing UML 2.0 Use Case meta-models..
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