Design of Low-Tension Cable Barrier Adjacent to Steep Slopes

Abstract

In the early 2000s, successful crash testing was performed according to the National Cooperative Highway Research Program (NCHRP) Report 350 criteria on a low-tension cable barrier installed adjacent to 1.5H:1V slopes that utilized a 4 ft post spacing and a 4 ft offset from the slope break point (SBP). Recently, the Nebraska Department of Transportation (NDOT) desired to investigate alternative low-tension cable barrier configurations that could satisfy the Manual for Assessing Safety Hardware (MASH) test level 3 (TL-3) impact conditions and potentially improve cost-effectiveness for NDOT. Dynamic component testing of cable posts was conducted as part of the research. Tests were conducted on S3×5.7 steel posts to evaluate the propensity for penetration of a small car vehicle’s floor pan, and floor pan tearing was observed. Subsequent component tests of an HSS3×2×1/8 tubular post alternative mitigated floor pan tearing. Computer simulations were performed to investigate alternative barrier configurations. Various combinations of post spacing, barrier offset, and cable heights were evaluated. It was determined that systems with 3 ft offset from the slope with 4 ft post spacing, or 4 ft offset from the slope with 6 ft post spacing, may perform acceptably according to MASH TL-3 test designation no. 3-11.