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ABSTRACT

A modified design of the MGS was evaluated for installation on a low-fill culvert with a strong-post attachment using to the culvert, half-post spacing, and a 12-in. (305-mm) offset from the back of the post to the culvert headwall through fullscale crash testing. A four-cell, concrete culvert with 8-in. (203-mm) thick slab and 9-in. (229-mm) deep soil fill was utilized. The test installation consisted of 182.3-ft (55.6-m) long MGS with a 31-in. (787-mm) top rail height, supported by twenty-three W6x8.5 by 72-in. (1,829-mm) long posts upstream and downstream of the culvert and fourteen W6x9 by 41-in. (1,041- mm) long posts attached to the culvert’s top slab using a deformable baseplate and through-bolts. Two crash tests were conducted according to the American Association of State Highway Transportation Officials (AASHTO) Manual for Assessing Safety Hardware 2016 (MASH) Test Level 3 (TL-3) impact safety criteria. In test no. CMGS-1, a 2,428-lb (1,101-kg) car impacted the culvert-mounted MGS at a speed of 61.3 mph (98.7 km/h) and at an angle of 25.1 degrees. In test no. CMGS-2, a 5,013-lb (2,274-kg) pickup truck impacted the MGS attached to the culvert at a speed of 62.8 mph (101.1 km/h) and an angle of 25.7 degrees. In both tests, the vehicle was safely redirected and captured. Both tests were deemed acceptable according to TL-3 safety criteria in MASH. Recommendations were made for the implementation of MGS on low-fill culverts as well as transitioning from the standard MGS to the culvert-mounted MGS.

KEYWORDS

Highway Safety, Crash Test, Roadside Appurtenances, Compliance Test, MASH 2016, Longitudinal Barrier, Culvert-Mounted, TL-3, Strong Post MGS

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