upper surface whereby the cap will fit snugly over the end of the post and impact forces can be applied to the cap to drive it into the ground it will be apparent that where the post is planted in a preformed hole prepared therefore in the ground the tip 24 collar 25 and cap 26 will not be required it will also be apparent that once the post has been planted by driving the cap 26 and collar 25 can be removed from the top of the post to be used in driving another post when the post 20 has been placed in the ground and a transverse impact force is applied thereto such as occurs if the post is struck by a motor vehicle or the like the post will bend as shown in fig5 and 6 with the impact causing the post to shear along the longitudinal weakened sections whether the shearing is complete along the lengths of the post or only partial the individual components formed after shearing occurs i e the central core and elongate rods will bend in response to such force application whether or not shearing between longitudinal weakend sections is complete will depend on the nature of the impact applied thereto if incomplete shearing occurs the individual components may bend or buckle see fig5 but since they are still partially connected they will readily resume the original post configuration it has been found that if the shearing is complete the individual components while tending to return to the original post shape do.