Subrack Solutions for Railway Signaling — High-Reliability Architecture for Next-Generation Train Control

Subrack (19’’Eurocard rack) has become the preferred mechanical platform for railway signaling and train control systems, including TCC, RBC, Interlocking, and CTC.

With standardized interfaces, modular expansion capability, and proven environmental reliability, it delivers the mechanical foundation required for modern, safety-critical railway control.

ØTechnical Challenges — What Rail Operators and Integrators Need to Solve

1. Slow fault recovery impacts system availability

 Dense wiring and non-modular structures make unit replacement time-consuming, directly affecting failover switchover and system uptime.

2. Safety-redundant architectures are difficult to scale

CTCS-2/3 requires 2oo2 or 3oo2 safety architectures. Many legacy platforms cannot easily expand CPU, safety I/O, power, or communication boards without re-wiring.

3. High-speed communication demands signal integrity and EMC robustness

RBC–GSM-R and TSRS–safety network links require stable high-speed differential channels with strict EMC performance.

4. Multi-system compatibility is costly

Upgrading between CTCS levels or adapting between CTCS and CBTC usually involves major mechanical redesign and cable changes.

5. Harsh mechanical environments require long-term stability

Railway equipment must withstand vibration, shock, EMC, and fire safety requirements throughout its operational life.

Subrack architecture is widely adopted because it directly addresses these system-level challenges.

ØTechnical Specifications Overview

• Mechanical Standard:

• 19” IEC 60297 compatible

• 6U, 84TE / 42TE Eurocard form factor

• Backplane Performance:

• High-speed differential backplane

• Supports up to 5 Gb/s

• Suitable for 100M/1G redundant communication

• Modular Board Architecture:

• Eurocard plug-in units: CPU, safety I/O, power modules, communication boards

• Hot-swappable design

• Module replacement within 3 minutes

• Environmental Reliability:

• IEC 61373 (vibration & shock)

• EN 50121-3-2 (EMC)

• EN 45545 (fire protection)

• System Compatibility:

• Supports CTCS-0/1/2/3, CBTC and hybrid systems

• Suitable for TCC, RBC, Interlocking (CBI), CTC, PSC (Platform Screen Door Safety Core)

ØWhy Subrack Is the Preferred Mechanical Platform for Railway Signaling

1. Standardized & Modular Design – Faster Maintenance, Higher Availability

Subrack platforms define plug-in boards as standard Line Replaceable Units (LRUs).

This enables:

• Hot-swap capability

• 3-minute board replacement

• Faster recovery during dual-system switchover

• Unified maintenance logic for both onboard and ground systems

This dramatically reduces operational downtime and maintenance effort.

2. Flexible Redundancy Architecture — Ideal for CTCS-2/3 Safety Requirements

Subrack + Eurocard connectors allow all core functions to be modularized:

• CPU

• Safety I/O

• Power modules

• Communication boards

Modules can be mixed, expanded, or replaced freely without re-wiring, enabling rapid deployment of 2oo2 / 3oo2 safety architectures.

3. High-Speed Backplane — Ensuring Signal Integrity for Safety-Critical Communication

With a 5 Gb/s differential backplane, the Subrack platform supports:

• RBC–GSM-R redundant communication

• TSRS–safety network high-bandwidth links

• Lower EMC risk due to optimized grounding and layout

This ensures stable and reliable communication for safety-critical systems.

4. Railway-Grade Mechanical and Environmental Durability

Designed for long-term operation in harsh rail environments, Subrack complies with:

• IEC 61373 vibration & shock

• EN 50121-3-2 EMC immunity

• EN 45545 fire safety

Ensuring dependable performance for high-speed rail, metro, and urban transit applications.

5. Multi-System Compatibility — Minimizing Upgrade and Retrofit Costs

In “Four-Network Integration” platform screen door projects, PSC (Platform Safety Controller) using Subrack architecture achieved:

• Direct compatibility with CBTC and CTCS-2

• Only interface boards need to be added or replaced

• Zero change to mechanical structure and wiring

This approach greatly reduces the engineering effort for upgrades such as CTCS-0 → CTCS-2, offering a highly cost-effective migration path.

Driving the Future of Railway Control Architecture

With its advantages in hot-swapping, high density, anti-vibration performance, and modular scalability, Subrack is rapidly expanding from onboard communications into ground-based CTCS safety platforms.

As the industry moves toward:

• Full electronic system architectures

• High-altitude sealing design

• Intelligent maintenance and diagnostics

• Zero-relay, zero-downtime, zero-maintenance platforms

Subrack is becoming the core mechanical carrier of next-generation train control systems.