An improved breakaway steel guardrail post for use in dissipation of impact energy upon impact of the post having an upper post member and a lower post member, a connecting joint, and a mechanism connected to the upper and lower post members for controlling the energy dissipation of the guardrail post about the connecting joint at a predetermined rate. A first embodiment utilizes a cable restraint lopped through openings in he guardrail posts. Other embodiments included straps and fasteners disigned to distort or fail at predetermined rates or strengths and combinations thereof
