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MGS with Curb and Omitted Post: Evaluation to MASH 2016 Test No. 3-11

REPORT NUMBER

TRP-03-433-21

AUTHORS

Scott Rosenbaugh, Samantha Corey

PUBLICATION DATE

2021-11-11

ABSTRACT

Curbs are often required along roadways for functions such as drainage control, right-of-way reduction, and sidewalk separation. However, when placed near guardrail systems, curbs can adversely affect the interaction of errant vehicles with roadside barriers and increase the propensity for vehicle underride, override, and instability increases. Further, curbed roadsides with soil backfill result in increased system stiffnesses and rail loads, which may lead to rail ruptures. Additionally, the presence of drainage features often interferes with the placement of guardrail posts, requiring a post to be omitted. Therefore, the system evaluated herein consisted of the Midwest Guardrail System (MGS) in conjunction with a curb and with an omitted post. The test article consisted of an MGS installation with the rail mounted 31 in. above the roadway and the front face of the guardrail located 6 in. behind a 6-in. tall AASHTO Type B curb. A single post was omitted near the middle of the system and 37 ft – 6 in. of nested rail was incorporated around the 150-in. elongated span created by the omitted post. In test no. MGSCO-4, a 2270P pickup truck impacted the system at a speed of 62.0 mph and at an angle of 25.1 degrees. The vehicle was successfully contained and redirected with no evidence of rail tearing. The vehicle remained stable, and all vehicle decelerations were within the allowable limits. Thus, test no. MGSCO-4 met the safety performance criteria of MASH test designation no. 3-11. The same system configuration was previously crash tested with the 1100C vehicle during test no. MGSCO-2 and met the safety performance criteria of MASH test designation no. 3-10. Therefore, the MGS with nested W-beam rail placed 6 in. behind a 6-in. tall AASHTO Type B curb and with an omitted post has been assessed as crashworthy to MASH TL-3. Recommendations and installation guidance for the MGS with omitted post placed adjacent to curbs were provided.