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Dynamic Evaluation of MGS Stiffness Transition with Curb




Brad Winkelbauer, Joe Putjenter, Scott Rosenbaugh, Karla Lechtenberg (Polivka), Bob Bielenberg, Ronald Faller, John Reid




A W-beam to thrie beam stiffness transition with a 4-in. (102-mm) tall concrete curb was developed to connect the 31-in. (787-mm) Midwest Guardrail System (MGS) to a previously-approved thrie beam approach guardrail bridge transition system. This stiffness transition was configured with standard steel posts that are commonly used by several State Departments of Transportation. The toe of a 4-in. (102-mm) tall sloped concrete curb was placed flush with the backside face of the guardrail and extended the length of the transition region. Three full-scale crash tests were conducted according to the Test Level 3 (TL-3) safety standards provided in AASHTO's Manual for Assessing Safety Hardware (MASH). During the first test, MASH test no. 3-20, the 1100C small car extended and wedged under the rail and contacted posts while traversing the curb. Subsequently, the W-beam rail ruptured at a splice location. A repeat of MASH test no. 3-20 was performed on an updated design which used a 12-ft 6-in. (3.81-m) long, nested W-beam rail segment upstream from the W-beam to thrie beam transition element. The 1100C small car was successfully contained and redirected. During MASH test no. 3-21, a 2270P pickup truck was successfully contained and redirected. Following the crash testing program, the system was deemed acceptable according to the Test Level 3 (TL-3) safety performance criteria specified in MASH.


Highway Safety, Crash Test, Roadside Appurtenances, Compliance Test, MASH, Curb, Asymmetric W-Beam to Thrie Beam Transition, Longitudinal Barrier, Approach Guardrail Transition, TL-3, Steel Post, Midwest Guardrail System, MGS

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