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ABSTRACT

The Minnesota Department of Transportation (MnDOT) desires to use a concrete parapet with a brush curb, upper beam and post rail, and a new tapered end section along high-speed highways and roadways when bridge structures are encountered. The MnDOT combination bridge railing system was full-scale crash tested according to the Test Level 4 (TL-4) procedures described in the Manual for Assessing Safety Hardware (MASH 2016). The combination bridge railing system consisted of a 21-in. tall concrete parapet with a 6-in. tall and 2-in. wide brush curb at the lower front face and eight rail and post assemblies, which consisted of one steel rail welded onto two or three steel posts with their own welded base plates. The steel assemblies were anchored to the top face of the concrete parapet.

In full-scale crash test nos. MNCBR-1, MNCBR-2, and MNCBR-3, the bridge railing system was evaluated according to MASH 2016 test designation nos. 4-12, 4-11, and 4-10, respectively. The 2013 International Durastar 4300 SBA single-unit truck impacted the system 60⅛ in. upstream from the centerline of the splice between post nos. 6 and 7 with a speed of 57.4 mph at an angle of 15.4 degrees. The 2014 Dodge Ram 1500 crew cab pickup truck impacted the system 69.9 in. upstream from the centerline of post no. 23 with a speed of 63.9 mph at an angle of 25.1 degrees. The 2009 Kia Rio small car impacted the system 70⁷∕₁₆ in. upstream from the centerline of post no. 23 with a speed of 62.5 mph at an angle of 25.5 degrees. The vehicles were successfully contained and redirected, resulting in minimal plastic deformation to the upper steel railing and moderate to minimal scraping and gouging of the concrete parapet. The combination bridge railing system was found to meet the AASHTO MASH 2016 TL-4 impact safety criteria.

KEYWORDS

Highway Safety, Crash Test, Roadside Appurtenances, Compliance Test, MASH 2016, Test Level 4, TL-4, High-Speed Highways and Roadways, Concrete Parapet, Brush Curb, Beam and Post, Hybrid Bridge Rail, and Combination Bridge Rail

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