Signalling Testing

Signalling Testing, more accurately Rolling Stock Signalling Interference Compatibility Testing, is an assessment conducted to evaluate the impact of new rolling stock on existing railway signalling infrastructure.

The purpose of this testing is to ensure that the introduction of new trains does not cause unacceptable electromagnetic interference (EMI) or other forms of disruption to signalling and communications systems.

Given the complexity and variability of railway networks, different regions and infrastructure managers have unique signalling systems, requiring tailored compatibility assessments. This testing forms an essential part of rolling stock validation and certification before deployment into revenue service.

Common signalling testing issues

Here are the common issues we address:

False energisation of track circuit relays on the track where the train is operating.
False energisation of track circuit relays on adjacent tracks.
Intermittent failure of track circuits on either the train’s operating track or adjacent tracks.
Lockout or failure of processor-based track circuits and other signalling equipment.
Interlocking system shutdowns or resets due to induced or capacitively coupled EMI.

Signalling systems are varied

Current signalling systems are based, to an increasing degree, on microprocessors, data communications and other sensitive electronics, whose operation can be affected by electromagnetic interference.

The objectives of signalling interference compatibility testing

The primary objectives of this testing are:

To determine whether the electromagnetic interference from the rolling stock exceed permissible limits and interfere with railway signalling systems.
To measure and assess the extent of rail-borne harmonic currents generated by the train under operating conditions on the networks and the potential impact of those on the network’s signalling infrastructure.
To verify the rolling stock’s ability to correctly detect on track circuits, electronic treadles, and axle counters.
To identify and mitigate potential risks associated with interference, ensuring seamless operation within existing infrastructure.

Compliance
Independent certification
Safety and Requirements
Q&A with Chinmay Sankhe

author Tash Francavilla

date 24th Feb 2025

We chat with one of Rail Confidence’s latest hires, Chinmay Sankhe, to discuss his specialisation in signalling compatibility testing.
Read more

Types of signalling systems assessed

Different signalling systems may be affected by rolling stock interference, including but not limited to:

Track Circuits

Track circuits are fundamental to railway safety, detecting the presence of trains on the tracks. New rolling stock must be tested to ensure that:

It does not cause unintended shunting of track circuits.
Its electrical systems (e.g., traction return current) do not generate interference that can falsely indicate track occupancy or clearance.

Axle Counters

Axle counters serve as an alternative to track circuits for train detection. The test assesses:

The rolling stock’s ability to correctly interact with axle counters without causing spurious counts.
Electromagnetic emissions that may interfere with axle counter sensor functionality.

How we test

Data Analysis & Validation – Engineers collect and analyse test data to identify anomalies, confirm compliance, and recommend corrective actions if needed.
Static Tests – Conducted while the train is stationary to measure electrical compatibility and ensure compliance with baseline requirements.
Dynamic Tests – Performed while the train is moving across different sections of the network to evaluate real-time interactions with the signalling system.

Networks

We work closely with relevant authorities and network managers to ensure that all testing is conducted in accordance with regulatory standards and expectations of the networks.

Throughout the testing process, we maintain transparent channels for feedback to keep in alignment with your project objectives.

Rail networks we work with