EN 14067-6: Railway Aerodynamics – Assessment of Crosswind Stability

What is EN 14067-6?

EN 14067-6 is a specialized part of the European Standard series titled “Railway applications – Aerodynamics – Part 6: Requirements and test procedures for crosswind assessment.” It addresses the risk of vehicle overturning or derailment caused by strong lateral wind gusts acting on a moving train.

As Rolling Stock becomes lighter to improve energy efficiency and speeds increase in High-Speed Rail, the susceptibility to crosswinds grows. This standard provides a harmonized methodology to calculate the safety limits of a vehicle and determines when operational restrictions (such as speed reductions) must be enforced during storm events.

The Assessment Methodology

The standard outlines a complex multi-step process to determine a vehicle’s stability. The goal is to calculate the Characteristic Wind Curve (CWC), which defines the maximum wind speed a train can safely withstand at various travel speeds.

• Wind Tunnel Testing: Scaled models of the vehicle are placed in a wind tunnel to measure aerodynamic coefficients (rolling moment, side force, and lift). This data is essential for understanding how the train’s shape reacts to different wind angles.
• Multi-body Simulation (MBS): The aerodynamic data is fed into a computer model of the train’s suspension and mass distribution. The simulation calculates the “wheel unloading”—the point at which the wind force starts to lift the wheels off the rail.
• Stochastic Analysis: The standard accounts for the randomness of wind gusts using statistical models to ensure safety even in unpredictable weather.

Safety Criteria and Limits

EN 14067-6 sets strict limits to prevent Derailment Risk. The primary safety criterion is the Wheel Unloading Ratio ($ΔQ/Q$). If the vertical load on the “windward” wheels drops below a certain percentage of the nominal load, the vehicle is considered unstable.

• Infrastructure Integration: The standard also allows infrastructure managers to use the vehicle’s CWC to install wind fences or wind-detection systems in high-risk areas like bridges or embankments.
• Reference Tracks: It defines standard track conditions (ballasted or slab track) and cant (banking) values to ensure the assessment is comparable across different rail networks.

Interoperability and TSI Compliance

Compliance with EN 14067-6 is mandatory for the certification of new trains under the Technical Specifications for Interoperability (TSI). It ensures that a train built in one country can safely operate on the “windy” coastal or alpine routes of another country without additional testing, provided its CWC is within the host network’s limits.

Comparison: Direct Measurement vs. MBS Simulation