EVALUATION OF TIMBER WEAK-POST GUARDRAIL SYSTEMS

SIX FULL-SCALE VEHICLE CRASH TESTS WERE CONDUCTED ON GUARDRAIL SYSTEMS TO EVALUATE THE EFFECTIVENESS OF SUBSTITUTING TIMBER POSTS FOR THE STANDARD 315.7 STEEL POSTS SPECIFIED IN A CURRENT GUARDRAIL STANDARD. RESULTS OF THE TESTS INDICATE THAT TIMBER IS A SUITABLE POST MATERIAL FOR THE "WEAK-POST" CONCEPT. ALTHOUGH THERE WAS SOME DIFFICULTY IN DETERMINING THE PROPER RAIL ATTACHMENT TO THE POST, SOLUTIONS TO THE PROBLEM ARE SUGGESTED IN THIS REPORT. THE TIMBER POST DESIGN CALLS FOR A 12-GAGE FLEXURAL BEAM MOUNTED ON 6- BY 7-IN. OR 5 1/2-IN. DIAMETER PINE POSTS SPACED AT 12.5-FT CENTERS. A 1/4-IN. DIAMETER STEEL BOLT AND A PIPE INSERT PROVIDE PROPER ATTACHMENT OF RAIL TO POST. THE SIXTH TEST OF THE SERIES PROVIDED AN EVALUATION OF THE EFFECTIVENESS OF A CONTINUOUS INSTALLATION COMPOSED OF THE NEW TIMBER WEAK-POST SYSTEM AND THE DEPARTMENT'S STRONG-POST SYSTEM. THE TEST RESULTS INDICATED THAT THE TRANSITION DESIGN BETWEEN THE TWO SYSTEMS WAS SATISFACTORY, BUT DESIGN CHANGES COULD IMPROVE PERFORMANCE. /AUTHOR/