Control Principles of PLC-Based Tram Switches

Urban tramway networks require reliable and safe turnout control systems that can operate efficiently under diverse traffic and environmental conditions. Traditional solutions, often based on manual or rudimentary automatic mechanisms, face limitations in terms of safety, adaptability, and maintenance. This paper proposes a Programmable Logic Controller (PLC)-based control application to manage tram switches. The system integrates key functionalities, including automatic operation via command shoes, detection of tram presence through pantograph contacts, manual override handling, external command integration, default position setting, and switch blade de-icing. A fail-safe design approach ensures that the turnout remains locked in uncertain conditions, prioritizing operational safety. Simulation tests validate the system’s ability to execute normal switching operations, handle manual and external commands, and return to default states. The proposed solution demonstrates the feasibility of using PLCs as a robust, modular, and cost-effective platform for enhancing the automation of tramway infrastructure, with direct applicability to modernization projects.