have a plurality of mounting apertures a therein the assembled energy dissipation plates 27 are positioned respectively within the energy absorbing compartments 26 by a plurality of fasteners f to the respective support pairs 11 14 in the barrier assembly 10 it will be apparent to those skilled in the art that the plates 27 can also be fabricated out of a plurality of thin milled plates to achieve the same structural result the energy dissipation plates 27 provide an improved energy absorbing structure when used in multiple units so that they are sequentially engaged by the impact of a vehicle against the barrier assembly 10 not shown referring now to fig4 8 of the drawings a supporting theoretical demonstration is illustrated wherein basic structural form of the assembled energy dissipation plates is illustrated as part of a diamond squashed on its top vertex see fig4 and 5 of the drawings and arranged schematically as a beam fixed at the bottom end loaded with force f applied to the top point p point p starts to move sensibly at yield i e when applied force f reaches yield point f y m y b and m y u03c3 y w where w modulus of the section u03c3 y yield stress variable during the application of the force referring now to fig6 of the drawings we consider now the flexural deformation of the fixing point for sensible movement of the point p being t thickness of the beam u03b5 t 2 sin u03b8 2 and the typical diagram u03c3 u03b5 for a ductile material is represented in fig7 where a o is the yield point stress we can approximate the top part of the diagram as o a o a sin u03b5 where a work hardening f sub y.