EN 15179: Braking Performance Requirements for High-Speed Trains

What is EN 15179?

EN 15179 is the European Standard titled “Railway applications – Braking – Requirements for the brake system of high-speed trains.” This standard is specifically designed for Rolling Stock operating at speeds equal to or greater than 190 km/h.

Because the kinetic energy of a train increases with the square of its speed ($E_k = \frac{1}{2}mv^2$), high-speed trains require vastly more sophisticated braking solutions than conventional trains. EN 15179 provides the technical framework to ensure that these trains can stop safely within signaled distances while maintaining passenger comfort and preventing damage to the track and wheels.

Core Requirements and Safety Criteria

The standard sets out strict parameters for the design and validation of the braking system. These are critical for Interoperability across the European high-speed network:

• Stopping Distance: Defines the maximum allowable distance to reach a complete standstill from various speeds under different environmental conditions (dry vs. wet rail).
• Braking Curve: Specifies the mandatory deceleration profile that the Signaling System (like ETCS) uses to calculate safety limits.
• Thermal Capacity: Requirements for brake discs and pads to dissipate the massive heat generated during an emergency brake from 300+ km/h without fading or structural failure.
• Adhesion Management: Standards for Wheel Slide Protection (WSP) systems to optimize the adhesion between the wheel and rail, preventing flat spots.

Redundancy and Reliability

EN 15179 mandates high levels of redundancy. The brake system must be designed so that a single failure (such as a burst pipe or a faulty electronic controller) does not result in the total loss of Braking Performance. It typically requires a combination of different braking technologies:

• Dynamic Braking: Using the traction motors as generators to dissipate energy.
• Friction Braking: High-performance disc brakes.
• Eddy Current Brakes: Non-contact magnetic braking used on some high-speed models to reduce wear at extreme speeds.

Testing and Validation

A train cannot be certified under TSI LOC&PAS without proving compliance with EN 15179 through:

• Static Tests: Verifying clamping forces and response times while the train is stationary.
• Dynamic Run Tests: Real-world “slip-brake” tests at maximum operational speeds to verify actual stopping distances.
• Degraded Mode Testing: Verifying that the train can still stop safely even if the dynamic brake or certain friction brake units are isolated.

Comparison: Conventional vs. High-Speed Braking (EN 15179)