Development and Evaluation of a MASH TL-3 31-Inch W-Beam Median Barriers.

摘要

Typically, when the G4(1S) W-beam barrier is impacted in a roadside application, the W-beam rail element deforms, the support posts are displaced through the soil, and the vehicle is redirected. During the impact sequence, the rail becomes detached from the post by means of the post bolt pulling out of the rail slot as the post displaces rearward. However, in the MB4 steel post W-beam median barrier, the addition of the rear W-beam rail element provides additional lateral stiffness and post constraint. This changes the post behavior and vehicle-post interaction. In a test of the 27-inch tall MB4 median barrier, the impacting pickup truck climbed and vaulted over the barrier. A taller 30.inch version of the MB4 W-beam median barrier (AASHTO Designation SGM06a&b) incorporates a C6x8.2 rub-rail channel to help mitigate vehicle-post snagging. However, the rub-rail may still permit the pickup to climb the barrier. The purpose of this project was to develop and evaluate a W-beam median barrier that would meet the strength and safety performance criteria of the AASHTO Manual for Assessing Safety Hardware (MASH). A 31.inch tall W-beam median barrier with rail splices offset from the posts and 8-inch offset blocks (AASHTO Designation SGM06a) was successfully crash tested in accordance with MASH.