Pioneering the Application of High Speed Rail Express Trainsets in ...

worthiness design of the trainset to cater to a 22 mph (36 km/h) impact as opposed to a 218
mph (350 km/h) collision.
CEM and crashworthiness are design philosophies embraced in passive safety system
design. CEM/crashworthiness designs provide a means of dissipating the energy produced
during a collision to provide protection to the occupants. The key safety parameters
addressed through crashworthiness are shown in Figure 3.2.
Figure 3.2 Key Safety Parameters of Crashworthiness
KEY SAFETY PARAMETERS OF CRASHWORTHINESS
• Reduce the risk of overriding.
• Absorb collision energy in a controlled manner.
• Maintain survival space and structural integrity of the occupied areas.
• Limit the deceleration.
• Reduce the risk of derailment and limit the consequences of hitting a track obstruction.
CEM systems are designed so that deformation of the trainset during a collision is controlled
to absorb the energy of the collision. The collapse zones are located in non-occupied
areas, typically those close to the extremities of each vehicle, in front of the cab, or adjacent
to intercar gangways.
3.2.1.1 Alstom
Alstom advised that it has embraced a CEM-based design philosophy beginning with
the TGV Duplex in the 1990s. It mentioned that passive safety was triggered by a TGV accident.
Other scenarios as identified in EN 15227 were developed from discussions of “feared
events.”
3.2.2 Dissipation of Collision Energy via Crash Energy Management
In discussing their approaches to designing trains for crashworthiness, manufacturers
were asked if evaluating kinetic energy 1 was the correct approach when determining the
requirements for CEM.
3.2.2.1 Alstom
Alstom advised that evaluating CEM designs relative to the dissipation of kinetic energy is
a correct approach. The various input parameters, which are vital in determining the energy
distribution and the shape and location of the CEM absorbers, typically include:
• A set of collision scenarios (e.g., EN 15227)
• A set of criteria related to the collision scenarios (deceleration, plastic strain, etc.)
• The train architecture.
1 Energy due to the speed of the train, defined as one-half of the body's mass times the square of its speed.
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