Development of a Missing Post Repair Guideline for Longitudinal Barrier Crash Safety

Abstract

Crash test procedures for modified steel strong-post w-beam guardrail are described in various U.S. Government reports. However, these tests are always performed on new guardrail installations. The performance of guardrail with posts removed because of damage or deterioration has never been quantitatively evaluated, leading to inconsistent U.S. repair guidelines. The effect of missing posts was quantitatively evaluated using crash tests and validated finite-element models of a guardrail and a 2,000 kg (4,409 lb) pickup truck. Simulations in which one, two, or three posts were removed from the guardrail were conducted with varying impact points to evaluate the effect of missing posts. The removal of a single post compromised vehicle safety because of snagging and airborne pitching and rolling. The risk of rail rupture increased as the impact load was shifted from the posts to the rails. A single missing post in a guardrail negatively affects the crash safety and should have a high repair priority.