A highway guardrail includes an elongated metal plate that forms at least one ridge. The plate includes weakened regions extending at least partially across the plate, and these weakened regions are oriented obliquely to the longitudinal direction to form at least one elongated fold region at which the plate tends to buckle when subjected to a sufficiently large column load. This fold region is oriented obliquely to the longitudinal direction to push the forward end of the guardrail downwardly in an axial collapse. The forward end of the guardrail includes a cable that passes through an opening in the forward support post. A split washer is positioned around this cable adjacent to the forward support post. The split washer includes first and second load transferring members that readily separate from one another after the first support post breaks at the opening in an axial impact.