Designed to Deform: EN 15227 and the Art of Railway Crashworthiness

What is EN 15227?

EN 15227 is the European Standard titled “Railway applications – Crashworthiness requirements for railway vehicle bodies.” It represents a paradigm shift in train design, moving from purely rigid structures to “Passive Safety” systems. While active safety (signaling, braking) aims to prevent accidents, EN 15227 ensures that if a collision does occur, the consequences for passengers and crew are minimized.

The standard mandates that the vehicle body must be designed to absorb collision energy in a controlled manner. This is achieved through dedicated Energy Absorption Elements (crumple zones) and anti-climbing devices. The goal is to preserve a “Survival Space” inside the cabin and passenger areas, ensuring that the train structure does not crush the occupants during an impact.

The Four Design Collision Scenarios

EN 15227 does not test for random accidents but requires validation against four specific, standardized collision scenarios. The severity of requirements depends on the vehicle category (e.g., high-speed trains vs. trams).

• Scenario 1: A front-end collision between two identical train units (typically at 36 km/h). The energy must be absorbed without deformation of the passenger/driver survival zones.
• Scenario 2: A front-end collision with a freight wagon equipped with side buffers (80 tonnes). This tests the compatibility of the train’s front structure with standard freight buffers.
• Scenario 3: Collision with a heavy obstacle (e.g., a 15-tonne truck) at a level crossing. This focuses on the structural integrity of the driver’s cab against intrusion.
• Scenario 4: Impact with a low obstacle (e.g., a car or animal) to ensuring the obstacle is pushed aside rather than causing derailment (using an obstacle deflector).

Key Technologies: Anti-Climbers and Crumple Zones

To meet these scenarios, modern trains are equipped with:

Anti-Climbers: Ribbed metal plates on the front of the train that interlock during a collision. They prevent one train from lifting off the tracks and “climbing” over the other, which is a major cause of fatalities in telescopic collisions.
Deformation Tubes: Sacrificial structural elements hidden behind the nose cone or couplers. They collapse telescopically to dissipate kinetic energy as heat and metal deformation, reducing the g-forces transferred to passengers.

Comparison: Traditional vs. EN 15227 Compliant Design