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Evaluation of a Modified Three Cable Guardrail Adjacent to Steep Slope




Ryan Terpsma, Karla Lechtenberg, Dean Sicking, John Rohde, John Reid, Ronald Faller




The three cable guardrail system is most commonly used to protect motorists from roadside slopes. Due to the fact that the system is limited to sites where relatively large barrier displacement is acceptable, concern arises when the system must be placed close to steep roadside slopes. The objective of this study was to evaluate a three cable barrier system placed adjacent to 1.5H:1V slopes. The three cable system in this test utilized quarter-post spacing. In addition, the offset from the slope break point was 1,219 mm (4 ft). One full-scale crash test, a 2,032-kg (4,481-lb) pickup truck impacting at a speed of 99.1 km/h (61.6 mph) and at an angle of 23.6 degrees, was conducted and reported in accordance with the requirements specified in the National Cooperative Highway Research Program (NCHRP) Report No. 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features. Based on the results and analysis of the full scale test, it was determined that the three cable guardrail system with quarter-post spacing and 1,219 mm (4 ft) offset from the slope break point performed adequately according to NCHRP Report No. 350 TL-3 requirements.


Highway Safety, Roadside Appurtenances, Cable Guardrail, Slope, Cable Anchor, Crash Testing, Compliance Testing

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