United States Department of Transportation
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Development of MASH TL-3 Transitions for Cast in Place Concrete Barriers
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2020-06-01
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[PDF-14.87 MB]
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Edition:September 2018–August 2019
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Abstract:The objective of this project was to develop transition designs for three cast in place concrete barrier combinations. These included transitions for connecting (a) TxDOT’s 36-inch tall Single Slope Traffic Rail (SSTR) to 42-inch tall Single Slope Concrete Barrier (SSCB), (b) 32-inch tall F-shape concrete barrier to SSCB, and (c)TxDOT’s 32-inch tall T221 vertical concrete wall to SSCB. The designs were required to meet AASHTO [Manual for Assessing Safety Hardware] MASH Test Level 3 (TL-3) criteria, and their compliance was to be evaluated using a combination of past testing results, impact simulation analyses, and limited full scale testing. Researchers developed designs and reinforcement details for all three transitions. The transition from SSTR to SSCB was comprised of a single slope barrier profile on the traffic side. This design did not require simulation or testing due to the known MASH compliance of the single slope barrier profile. Researchers developed designs of the other two transitions by performing dynamic vehicular impact simulations using MASH TL-3 impact conditions. Using results of these simulations, researchers selected the most critical cases for performance of full scale crash tests. The design selected for full scale testing was the transition between T221 and SSCB. MASH requires performing Test 3-20 (small car) and Test 3-21 (pickup) to evaluate transition designs. Both tests were performed on the transition between T221 and SSCB. The direction of vehicle impact in both tests was from the side of the SSCB to T221, which was selected based on simulation results. The transition performed acceptably in both tests for MASH TL-3 criteria. Based on the results of the simulations for F-shape to SSCB transition, and the fact that the more critical design of T221 to SSCB transition passed MASH testing, the F-shape to SSCB transition was also considered a MASH compliant design. This report provides details of the transition designs, simulation analyses, reinforcement details, and a detailed documentation of the MASH crash testing.
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