Improvements to the Weak-Post W-Beam Guardrail

Abstract

The weak-post W-beam guardrail has been widely used in the Northeast for many decades. Weak-post guardrails are characterized by larger dynamic deflections in a collision and are considered more forgiving than other, stiffer barriers. Most states have experienced good performance with these barriers over the last several decades if adequate clear space is provided behind the barrier. Unfortunately, recent crash tests of the standard weak-post W-beam guardrail involving a 2000-kg pickup truck resulted in a series of unacceptable test results, including overriding and penetrating the guardrail. Design modifications to the weak-post W-beam guardrail were explored by using finite element simulations and full-scale crash tests. An improved version of the weak-post W-beam guardrail system was developed and tested, and this was found to satisfy the requirements of NCHRP Report 350 for Test Level 3.