is intended to reduce the speed of the vehicle through impact and also cause the vehicle to u201c jump u201d according to the embodiment when the vehicle reaches the deformable zone 3 it not only bears on bed 9 but it also descends upon the surface cover layer 7 and bed 9 with a generally vertical impact force as shown schematically in fig5 the first impact element in the form of the curb 2 may be formed of stone reinforced concrete wood etc as well the curb may be capped with steel and or pinned to a foundation below not shown for additional strength according to a preferred embodiment the curb 2 has a height that is typically in a range of approximately 3 inches to 12 inches high above the level of the trafficable surface but may be provided with any suitable height for use with a barrier for intended vehicle types according to the illustrated embodiment the deformable zone 3 comprises a surface cover layer 7 a bed 9 having a deformable structure or material for lowering the elevation of the vehicle and a confining structure 8 the top of surface cover layer 7 e g formed from a material such as concrete brick pavers tiles cobble planting.