What is Normalised Dynamic Deflection? 


Normalised Dynamic Deflection is the second parameter to evaluate the deformation of the system under impact and it is calculated as the distance between the traffic face of the system in its initial condition and it maximum displacement.  The dynamic deflection is measured in meters.


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It is up to national regulations (not the EN 1317) to define the criteria that road designers should follow to define the maximum dynamic deflection of the system to be used on the road, when designing the roadside.