Testing Automatic Train Stop (ATS) systems is essential to ensure the system will properly protect train movements when unsafe conditions occur. Testing verifies the operation of both trackside and onboard equipment, as well as the effectiveness of the automatic brake application.
For mechanical trip ATS systems, the trackside trip arm must be inspected to ensure it raises and lowers correctly based on the signal aspect. Maintainers should check for proper movement, correct height, and any mechanical binding or obstructions.
The onboard trip cock must also be inspected to verify proper installation, alignment, and freedom of movement. The trip cock must be capable of correctly engaging the trackside trip arm when required.
Controlled interaction tests are often performed at very low speeds. During these tests, the train intentionally passes a restrictive signal under controlled conditions to verify that the trip arm activates the trip cock and initiates an automatic brake application.
Inductive ATS systems require testing of the trackside inductors, transmitters, and onboard receivers. Technicians verify that the proper signal information is transmitted and correctly received by the train.
Speed monitoring systems must also be calibrated and tested. Accurate speed information is critical because ATS systems rely on train speed to determine when warnings or brake applications are necessary.
Overspeed testing is typically performed in a controlled environment. The train speed is gradually increased beyond a designated speed limit while technicians verify that the ATS system issues warnings and applies brakes when required.
Simulated SPAD testing may also be performed. These tests verify that the ATS system correctly responds when the onboard equipment receives information indicating a train has passed a stop signal.
Audible and visual warning systems must be tested to ensure train crews receive proper notification before automatic brake intervention occurs.
One of the most important parts of ATS testing is verifying that the automatic brake application is effective. The system must be capable of safely stopping the train when required.
Detailed records of all testing activities, results, adjustments, and maintenance actions should be maintained to support system reliability and regulatory compliance.