Weak-Post W-Beam Guardrail Attachment to Culvert Headwalls

Abstract

A new W-beam guardrail system for use on low-fill culverts was developed and evaluated. The system was adapted from the Midwest Guardrail System (MGS) bridge railing for attachment to the outside face of culvert headwalls. Four attachment concepts were developed and evaluated through dynamic component testing. Both lateral and longitudinal impacts were conducted on the design concepts while mounted to a concrete culvert headwall. The resultant damage from each test was confined to post bending. Although all four designs prevented damage to the socket assembly and culvert headwall, the top-mounted, single-anchor design and the side-mounted design were recommended for use on the basis of ease of fabrication and installation. The new W-beam guardrail system for attachment to low-fill culverts was designed with multiple advantages over current culvert treatments. The guardrail system mounts to the outside face of the headwall. Thus it minimizes intrusion over the culvert and maximizes the traversable roadway width. The barrier has an unrestricted system length and does not require a transition when attached to a standard MGS. The attachment configurations were designed with epoxy anchors to enable system installment on new or existing culverts. Finally, implementation guidance was provided for new system installations.