Installation Guidelines for Midwest Guardrail System on Curbed Roadways for MASH TL-3 Applications

Abstract

The objective of this project was to develop installation guidelines for the placement of the Midwest Guardrail System (MGS) in combination with roadside curbs to satisfy the Manual for Assessing Safety Hardware (MASH) Test Level 3 (TL-3). A combination of vehicle trajectory tests, LS-DYNA simulations, and MASH crash testing were used to achieve this objective. Two vehicle trajectory tests, using a 2270P pickup and an 1100C small car, were conducted with the vehicles traversing over a 6 in. tall, American Association of State Highway and Transportation Officials Type B curb at impact conditions consistent with MASH TL-3. The suspensions of LS-DYNA models for these MASH vehicles were updated, and validated to match the vehicle trajectories measured during the curb traversal tests. The updated vehicle models were then used to simulate MASH TL-3 impacts with the MGS set at various offsets behind the curb. An offset of 6 ft was selected as the maximum offset for the MGS behind the curb. Two MASH crash tests were conducted on the MGS placed behind the curb. A MASH 3-11 test was conducted with the MGS offset 6 ft behind a 6 in. curb to evaluate override and instability concerns, while a MASH 3-10 test was conducted with a 1 ft offset to evaluate underride and snag. Both tests passed MASH TL-3 safety performance criteria. Additional simulations showed that reduced impact speeds and angles did not cause any vehicle containment or stability concerns. Thus, the MGS with a height of 31 in. relative to the top of the curb was considered MASH TL-3 crashworthy when installed at offsets between 1 and 6 ft behind a roadside curb.