Short Radius MASH TL-3 Guardrail Treatment

When a roadway intersects a highway with restrictive features such as a bridge rail and canal, it becomes difficult to fit a guardrail with the proper length, transitions, and end treatment along the highway. Possible solutions include relocating the constraint blocking the placement of the guardrail, shortening the designed guardrail length, or designing a curved guardrail. Curved, or short radius, guardrails typically present the most viable solution for these areas. However, no previously designed short radius guardrails meet National Cooperative Highway Research Program (NCHRP) Report 350 Test Level 3 (TL-3) guidelines. Now, the American Association of State Highway and Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH) has updated crash testing criteria. The new guidelines supersede NCHRP Report 350 and increased the size of test vehicles and changed the test matrices to include more impact conditions. Therefore, meeting new impact standards for short radius guardrails has become more challenging. TTI researchers investigated, modeled, and simulated an optimized short radius design under this project. Subsequently, the researchers successfully conducted full-scale crash tests to MASH 3-33, 3-32, 3-31, and 3-35 test conditions. This innovative design uses an energy dissipation component plus a cable anchor that provides tension capacity to the rail section on the primary roadway. These new innovative design details made the system very effective in capturing the vehicles in short distances while using readily available components.