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Network Rail, CTRL Tunnel Ventilation Control
Morson Praxis’ was appointed by Network Rail to provide specialist software engineering and systems assurance for the implementation of the Ventilation Control System (VCS) across the three Channel Tunnel Rail Link (CTRL) tunnels.
Client Brief
Ensuring Safety and Reliability for High-Speed Rail Operations
Network Rail required a robust, safety-critical ventilation control system capable of supplying and extracting air within the CTRL tunnels during both normal train operations and emergency scenarios. The system needed to meet stringent safety integrity standards while offering full redundancy, continuous availability, and reliable operator control.
Project Overview
Developing a High-Integrity Ventilation Control System
The VCS project focused on designing and implementing a fully integrated Mitsubishi PLC and Citect SCADA system architecture to control and monitor tunnel ventilation.
To meet operational safety and reliability requirements, the system development adhered to BS EN 51028 SIL 3 guidelines and was regularly audited to ensure compliance.
Key components included redundant PLCs, dual-redundant SCADA servers, and networked control interfaces distributed across vent shafts and tunnel portals.
Image Gallery
Explore the advanced Ventilation Control System engineered for the CTRL tunnels — combining safety, innovation, and reliability in every detail.
Our Solution
Comprehensive Engineering and Integration Delivery
Morson Praxis delivered the full design, installation, and commissioning of the VCS, supported by advanced control and monitoring architecture:
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Systems Delivered:
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Mitsubishi PLC Control System (SIL 3 compliant)
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Citect SCADA System (SIL 2 compliant)
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Remote Monitoring and High Availability Architecture
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Integrated Central Database
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SIL 2 & 3 Development Framework
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Services Provided:
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System Architecture Design
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Software Development & SCADA Systems Integration
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Network Infrastructure Design
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Electrical Services, Installation & Commissioning
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Site Surveys, CAD Drawings & Containment Design
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Audit & Obsolescence Studies
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Training
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The SCADA system was engineered for maximum uptime using a dual-redundant network configuration, ensuring continued operation in the event of a failure. Operator stations were configured with dedicated functions but designed to be interchangeable for resilience.
The PLC system featured a duty/standby pair of Mitsubishi “Q” series PLCs, ensuring continuous supervisory control even in the event of SCADA unavailability. Manual override pushbutton stations and Forward Incident Control Panels (FICPs) provided fail-safe manual control during critical scenarios.
Results
A Fully Compliant, High-Reliability Ventilation System
The delivered VCS now provides Network Rail with a safety-assured, resilient control platform, enabling real-time monitoring and automated response to both normal and emergency tunnel conditions.
This system not only meets SIL 2 and SIL 3 standards, but also enhances operator visibility, system redundancy, and fault tolerance—ensuring optimal safety, reliability, and operational continuity across the CTRL tunnels.
