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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls. Washington, DC: The National Academies Press. doi: 10.17226/26580.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls. Washington, DC: The National Academies Press. doi: 10.17226/26580.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls. Washington, DC: The National Academies Press. doi: 10.17226/26580.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls. Washington, DC: The National Academies Press. doi: 10.17226/26580.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls. Washington, DC: The National Academies Press. doi: 10.17226/26580.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls. Washington, DC: The National Academies Press. doi: 10.17226/26580.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls. Washington, DC: The National Academies Press. doi: 10.17226/26580.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls. Washington, DC: The National Academies Press. doi: 10.17226/26580.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls. Washington, DC: The National Academies Press. doi: 10.17226/26580.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls. Washington, DC: The National Academies Press. doi: 10.17226/26580.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls. Washington, DC: The National Academies Press. doi: 10.17226/26580.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls. Washington, DC: The National Academies Press. doi: 10.17226/26580.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls. Washington, DC: The National Academies Press. doi: 10.17226/26580.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls. Washington, DC: The National Academies Press. doi: 10.17226/26580.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls. Washington, DC: The National Academies Press. doi: 10.17226/26580.
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NCHRP Web-Only Document 326 Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls Roger P. Bligh Jean-Louis Briaud Akram Abu-Odeh Deeyvid O. Saez Layal S. Maddah Kang Mi Kim Texas A&M Transportation Institute College Station, TX Conduct of Research Report for NCHRP Project 22-20(02) Submitted June 2017 NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed, and implementable research is the most effective way to solve many problems facing state departments of transportation (DOTs) administrators and engineers. Often, highway problems are of local or regional interest and can best be studied by state DOTs individually or in cooperation with their state universities and others. However, the accelerating growth of highway transportation results in increasingly complex problems of wide interest to highway authorities. These problems are best studied through a coordinated program of cooperative research. Recognizing this need, the leadership of the American Association of State Highway and Transportation Officials (AASHTO) in 1962 initiated an objective national highway research program using modern scientific techniques—the National Cooperative Highway Research Program (NCHRP). NCHRP is supported on a continuing basis by funds from participating member states of AASHTO and receives the full cooperation and support of the Federal Highway Administration (FHWA), United States Department of Transportation, under Agreement No. 693JJ31950003. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FTA, GHSA, NHTSA, or TDC endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. DISCLAIMER The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research. They are not necessarily those of the Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; the FHWA; or the program sponsors. The Transportation Research Board does not develop, issue, or publish standards or specifications. The Transportation Research Board manages applied research projects which provide the scientific foundation that may be used by Transportation Research Board sponsors, industry associations, or other organizations as the basis for revised practices, procedures, or specifications. The Transportation Research Board, the National Academies, and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturers’ names appear herein solely because they are considered essential to the object of the report. The information contained in this document was taken directly from the submission of the author(s). This material has not been edited by TRB.

The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, non- governmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president. The National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. John L. Anderson is president. The National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president. The three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. The National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine. Learn more about the National Academies of Sciences, Engineering, and Medicine at www.nationalacademies.org. The Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. The mission of the Transportation Research Board is to provide leadership in transportation improvements and innovation through trusted, timely, impartial, and evidence-based information exchange, research, and advice regarding all modes of transportation. The Board’s varied activities annually engage about 8,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation. Learn more about the Transportation Research Board at www.TRB.org.

C O O P E R A T I V E R E S E A R C H P R O G R A M S CRP STAFF FOR NCHRP WEB-ONLY DOCUMENT 326 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs Waseem Dekelbab, Associate Program Manager, National Cooperative Highway Research Program David Jared, Senior Program Officer Traci Caldwell, Senior Program Assistant Natalie Barnes, Director of Publications Heather DiAngelis, Associate Director of Publications Jennifer Correro, Assistant Editor NCHRP PROJECT 22-20(02) PANEL Field of Design—Area of Vehicle Barrier Systems Alexander K. Bardow, Massachusetts Department of Transportation, Boston, MA (Chair) Robert L. Chen, WSP, Irvine, CA Ronald K. Faller, University of Nebraska, Lincoln, Lincoln, NE Robert A. Gladstone, Association for Mechanically Stabilized Earth, Richmond, VA Grant Gummow, Utah Department of Transportation, Salt Lake City, UT Ramesh C. Gupta, SAR6 Inc, Ashburn, VA Christopher Hahin, Illinois Department of Transportation, Springfield, IL Michael Lee McMullen, Colorado Department of Transportation, Denver, CO Silas C. Nichols, FHWA Liaison Stephen F. Maher, TRB Liaison ACKNOWLEDGMENT We would like to acknowledge the support and the assistance of the following people and institutions: The Reinforced Earth Company (RECo); Mr. Pete Anderson, Mr. Carl Sanders and Mr. David Hutchinson; Texas A&M Supercomputing (SC) Facilities and staff; Texas A&M Proving Ground researchers and staff; Dr. Chuck Plaxico; Dr. Jose Roesset; Dr. Robert Warden; and Dr. James Murff. Portions of this research were conducted with the advanced computing resources provided by Texas A&M High Performance Research Computing.

iv TABLE OF CONTENTS LIST OF FIGURES ..................................................................................................................... viii LIST OF TABLES ....................................................................................................................... xiv SUMMARY .................................................................................................................................... 1 1 INTRODUCTION .................................................................................................................... 4 1.1 Problem Statement ......................................................................................................... 4 1.2 Objectives ....................................................................................................................... 6 1.3 Research Approach ......................................................................................................... 8 1.3.1 Phase I: Analytical Study ........................................................................................... 8 1.3.2 Phase II: Experimental Study..................................................................................... 9 1.4 Organization of this Report ............................................................................................ 9 2 STATE OF PRACTICE FOR BARRIERS AND MSE WALLS ........................................... 11 2.1 Design of Mechanically Stabilized Earth (MSE) Wall System ................................... 11 2.1.1 Design and Construction Methods ........................................................................... 11 2.1.2 LRFD vs. ASD Design Approach ............................................................................ 15 2.2 Design and Evaluation of Longitudinal Barrier and Bridge Rails ............................... 17 2.2.1 Guidelines for Barrier Evaluation ............................................................................ 17 2.2.2 Barrier Design .......................................................................................................... 18 2.2.3 Full-Scale TL-4 Crash Testing................................................................................. 20 2.2.4 Full-Scale TL-5 Crash Testing................................................................................. 21 2.3 Background on Design Impact Load for Heavy Vehicles ............................................ 23 2.4 Roadside Barrier System atop of MSE Walls .............................................................. 30 2.4.1 Full-Scale Crash Tests of Barriers on Top of MSE Walls ....................................... 31 2.4.2 Design of Barriers and MSE Walls for Vehicle Impact .......................................... 37 3 PEAK DYNAMIC LOAD ...................................................................................................... 39 3.1 Impact Load Study for TL-3 Impact ............................................................................ 39 3.1.1 Finite Element Model .............................................................................................. 40 3.2 Impact Load Study for TL-4 Impact ............................................................................ 44 3.2.1 Analytical Study....................................................................................................... 44 3.2.2 Finite Element Analyses for MASH TL-4 Impact ................................................... 46 3.3 Impact Loads Study for Test Level 5 Impact ............................................................... 57 3.3.1 Analytical Study....................................................................................................... 57 3.3.2 Finite Element Analyses for MASH TL-5 Impact ................................................... 58 3.4 Recommendation of Design Impact Loads in Traffic Barriers for Mash TL-4 and TL-5 Impact ........................................................................................................... 70 4 MOMENT SLAB WIDTH ..................................................................................................... 72 4.1 Dynamic Finite Element Analyses Model .................................................................... 72 4.1.1 Modeling Methodology ........................................................................................... 72 4.1.2 Analyses for Test Level 4 Impact ............................................................................ 77 4.1.3 Analyses for Test Level 5 Impact with 42-in. (1.07 m) tall barrier (TL-5-1) .......... 82 4.1.4 Analyses for Test Level 5 Impact with 48-in. (1.22 m) tall barrier (TL-5-2) .......... 87 4.2 Static Analysis of the Barrier-Moment Slab System .................................................... 92

v 4.2.1 Static Analytical Solution ........................................................................................ 93 4.2.2 Quasi-static FE Analyses ......................................................................................... 94 4.3 Conclusions .................................................................................................................. 97 5 REINFORCEMENT LOADS ............................................................................................... 100 5.1 Full-Scale MSE Wall FE Analyses ............................................................................ 100 5.1.1 MSE Wall Capacity ............................................................................................... 101 5.1.2 Modeling Methodology ......................................................................................... 101 5.2 MSE Wall FE Analyses for TL-4 Impact ................................................................... 105 5.2.1 Loads and Displacements in the Barrier ................................................................ 106 5.2.2 Loads and Displacement in the Soil Reinforcements ............................................ 106 5.2.3 Wall Panel Analyses .............................................................................................. 114 5.3 MSE Wall FE Analyses for TL-5 Impact on a 42-in. (1.07 m) Tall Barrier (TL-5-1) ...................................................................................................................... 116 5.3.1 Loads and Displacements in the Barrier ................................................................ 118 5.3.2 Loads and Displacement in the Soil Reinforcement .............................................. 121 5.3.3 Wall Panel Analyses .............................................................................................. 124 5.4 MSE Wall FE Analyses for TL-5 Impact on a 48-in. (1.22 m) Tall Barrier (TL-5-2) ...................................................................................................................... 126 5.4.1 Loads and Displacements in the Barrier ................................................................ 128 5.4.2 Loads and Displacements in the Soil Reinforcement ............................................ 132 5.4.3 Wall Panel Analyses .............................................................................................. 135 5.5 Conclusions ................................................................................................................ 136 6 TL-4 FULL-SCALE TEST ON TOP OF A 10-FT HIGH MSE WALL .............................. 140 6.1 Description of the Barrier-Moment Slab and MSE Wall ........................................... 140 6.1.1 Calculation of MSE Wall Capacity ........................................................................ 142 6.1.2 Calculation of the Barrier Capacity ....................................................................... 142 6.2 Finite Element Analyses ............................................................................................. 143 6.2.1 Lateral Impact Load on Barrier .............................................................................. 146 6.3 TL-4 Crash Test .......................................................................................................... 147 6.3.1 Test Planning and Setup ......................................................................................... 147 6.3.2 Instrumentation ...................................................................................................... 148 6.3.3 TL-4 Crash Test ..................................................................................................... 150 6.3.4 Reported Damage ................................................................................................... 151 6.3.5 Test Results ............................................................................................................ 152 7 TL-5 FULL-SCALE TEST ON TOP OF A 10-FT HIGH MSE WALL .............................. 159 7.1 Description of the Barrier-Moment Slab and MSE Wall ........................................... 159 7.1.1 Calculation of MSE Wall Capacity ........................................................................ 160 7.1.2 Calculation of Barrier Capacity ............................................................................. 160 7.2 Finite Element Analyses ............................................................................................. 161 7.2.1 Barrier Damage and Displacement ........................................................................ 165 7.2.2 Loads and Displacements in the Reinforcing Strips .............................................. 168 7.2.3 Panels Analyses ..................................................................................................... 171 7.3 TL-5 Crash Test .......................................................................................................... 173 7.3.1 TL-5 MSE Wall Construction and Test Installation .............................................. 174

vi 7.3.2 Impact Conditions .................................................................................................. 185 7.3.3 Test Vehicle ........................................................................................................... 185 7.3.4 Weather Conditions ............................................................................................... 186 7.3.5 Test Description ..................................................................................................... 187 7.3.6 Test Article and Component Damage .................................................................... 187 7.3.7 Test Vehicle Damage ............................................................................................. 187 7.3.8 Occupant Risk ........................................................................................................ 192 7.3.9 Data from Accelerometers ..................................................................................... 192 7.3.10 Photographic Instrumentation ................................................................................ 197 7.3.11 Loads in the Strips from the Strain Gages ............................................................. 197 7.3.12 Panel Analysis ........................................................................................................ 204 7.3.13 Other Instrumentation ............................................................................................ 206 7.3.14 Damage of Moment Slab after Test ....................................................................... 212 7.4 Conclusions ................................................................................................................ 213 7.5 Comparison of Test and Simulation ........................................................................... 213 8 STATIC LOAD TEST ON TL-5 BARRIER-MOMENT SLAB SYSTEM ........................ 226 8.1 Static Analytical Solution ........................................................................................... 226 8.2 Quasi-static FE Analyses ............................................................................................ 228 8.3 Full-Scale Static Load Test ........................................................................................ 230 8.4 Comparison of Test and Simulation ........................................................................... 239 8.5 Conclusion .................................................................................................................. 240 9 DESIGN GUIDELINES FOR BARRIER-MOMENT SLAB SYSTEMS MOUNTED ON MSE WALLS FOR TL-3 THROUGH TL-5 IMPACTS ............................................... 241 9.1 Guidelines for the Barrier ........................................................................................... 244 9.1.1 Sliding of the Barrier ............................................................................................. 244 9.1.2 Overturning of the Barrier ..................................................................................... 245 9.1.3 Rupture of the Coping in Bending ......................................................................... 245 9.2 Guidelines for the Wall Reinforcement ...................................................................... 247 9.2.1 Pullout of the Wall Reinforcement ........................................................................ 247 9.2.2 Yield of the wall Reinforcement ............................................................................ 251 9.3 Data to Back up Guidelines for TL-3 throughTL-5 ................................................... 254 9.3.1 Limit States ............................................................................................................ 254 9.3.2 General procedure for load determination ............................................................. 255 9.3.3 Selection of Serviceability Limits .......................................................................... 257 9.3.4 Data for TL-3 ......................................................................................................... 262 9.3.5 Data for TL-4-1 and TL-4-2 .................................................................................. 268 9.3.6 Data for TL-5-1 ...................................................................................................... 279 9.3.7 Data for TL-5-2 ...................................................................................................... 286 10 AASHTO LRFD FORMAT DESIGN GUIDELINES ......................................................... 294 1.1 SCOPE ........................................................................................................................ 294 1.2 DEFINITIONS ........................................................................................................... 295 1.3 NOTATION ............................................................................................................... 295 1.4 GUIDELINES FOR THE BARRIER ........................................................................ 297 1.4.1 General ................................................................................................................... 297

vii 1.4.2 Sliding of the Barrier ............................................................................................. 298 1.4.3 Overturning of the Barrier ..................................................................................... 299 1.4.4 Design of the Coping ............................................................................................. 300 1.5 GUIDELINES FOR THE SOIL REINFORCEMENT .............................................. 301 1.5.1 General ................................................................................................................... 301 1.5.2 Pullout of the Soil Reinforcement .......................................................................... 302 1.5.3 Yielding of the Soil Reinforcement ....................................................................... 304 REFERENCES ........................................................................................................................... 306 APPENDIX A: DESIGN OF MSE WALL FOR TL-4 IMPACT .............................................. 311 APPENDIX B: DETAILED DRAWINGS OF THE TL-4 TEST INSTALLATION ................ 316 APPENDIX C: SEQUENTIAL PHOTOGRAPHS FOR TL-4 TEST ....................................... 324 APPENDIX D: DESIGN OF TL-5 MSE WALL TEST INSTALLATION USING RECOMMENDED DESIGN PARAMETERS .................................................................... 326 APPENDIX E: DETAILED DRAWINGS OF THE TL-5 WALL TEST INSTALLATION .... 334 APPENDIX F: CONSTRUCTION SEQUENCE OF THE TL-5 MSE WALL TEST INSTALLATION ................................................................................................................. 345 APPENDIX G: TL-5 SEQUENTIAL PHOTOGRAPHS ........................................................... 354 APPENDIX H: TL-5 TEST VEHICLE PROPERTIES ............................................................. 357

viii LIST OF FIGURES Figure 1-1 Sketch of an MSE retaining wall with a barrier-moment slab system (2) .............. 7 Figure 1-2 Sketch of FE models on barrier-moment slab systems ........................................... 7 Figure 2-1 External stability considerations (11) ................................................................... 12 Figure 2-2 Internal stability considerations (AASHTO LRFD Figure 11.10.7.2.-1) (3)........ 13 Figure 2-3 Default values for the pullout friction factor, F*(AASHTO LRFD Figure 11.10.6.3.2-1) (3) .................................................................................................. 14 Figure 2-4 Idealized (a) mid-span and (b) end of rail failure mechanisms (3). ...................... 20 Figure 2-5 Mathematical model of vehicle-barrier railing collision (33). .............................. 25 Figure 2-6 Impact force prediction based on NCHRP Report 86 mathematical models (34). ....................................................................................................................... 26 Figure 2-7 50-msec. average acceleration impact force-Test 7046-3 (13) ............................. 29 Figure 2-8 50-msec. average acceleration impact force-Test 7046-4 (13) ............................. 29 Figure 2-9 50-msec. average acceleration impact force -Test 7046-9 (13) ............................ 29 Figure 2-10 Comparison of static and dynamic overturning tests (2) ...................................... 32 Figure 2-11 Full-scale test for 5-ft high MSE wall with a bogie (2) ........................................ 33 Figure 2-12 Barrier on MSE wall prior to testing (2) ............................................................... 34 Figure 2-13 Summary of results for MASH test 3-11 on the MSE wall (2). ........................... 35 Figure 2-14 Distribution of stress from concentrated horizontal loads (AASHTO LRFD Figure 3.11.6.3-2 a) (3) ......................................................................................... 37 Figure 2-15 Soil reinforcement pressure distribution (NCHRP Report 663) (2) ..................... 38 Figure 3-1 TL-3 simulation and crash test vehicles ................................................................ 39 Figure 3-2 Three-dimensional view of MSE wall, barrier, and C25000 Vehicle Model ....... 40 Figure 3-3 2000P pickup truck impact force on barrier (50-msec. average) (Source: NCHRP Report 663 (2) p.128) ............................................................................. 41 Figure 3-4 Side view of barrier-moment slab system and MASH TL-3 with the 2270P- pickup truck model. .............................................................................................. 41 Figure 3-5 Sequential images for 2270P-pickup truck test (2) and simulation ...................... 42 Figure 3-6 Comparison of acceleration and angular displacements between MASH ............ 43 Figure 3-7 MASH TL-3 impact force versus time history for barrier impact (50-msec. average) ................................................................................................................. 44 Figure 3-8 Sequential images for SUT test (18) and simulation ............................................ 47 Figure 3-9 Comparison of acceleration and angular displacements between test 476460-1b (18) and simulation. ............................................................................ 48 Figure 3-10 MASH TL-4 FE model for the 36-in. (0.91 m) tall barrier and tall vertical wall ........................................................................................................................ 49 Figure 3-11 Results of the MASH TL-4 impact simulation on the 36-in. (0.91 m) tall vertical wall. .......................................................................................................... 51 Figure 3-12 Results of the MASH TL-4 impact simulation on the 39-in. (0.99 m) tall vertical wall. .......................................................................................................... 52 Figure 3-13 Results of the MASH TL-4 impact simulation on the 42-in. (1.07 m) tall vertical wall. .......................................................................................................... 53 Figure 3-14 Results of the NCHRP 350 and MASH TL-4 impact simulation on the tall vertical wall. .......................................................................................................... 54 Figure 3-15 Variation of impact force for different barrier heights for MASH TL-4 .............. 55 Figure 3-16 Comparison of contact area between barriers for MASH TL-4 impact. ............... 56

ix Figure 3-17 Enhanced FE tractor-trailer model developed by NTRC (40-41) ......................... 60 Figure 3-18 MASH TL-5 FE model for the 42-in. (1.07 m) tall barrier and the tall vertical wall ........................................................................................................... 61 Figure 3-19 TL-5 impact force and distribution on the 42-in. (1.07 m) tall vertical barrier. ................................................................................................................... 62 Figure 3-20 TL-5 impact force and distribution on the 48-in. (1.22 m) tall vertical barrier .................................................................................................................... 64 Figure 3-21 TL-5 impact force and distribution on the 54-in. (1.37 m) tall vertical barrier .................................................................................................................... 65 Figure 3-22 TL-5 impact force and distribution on the tall vertical barrier ............................. 67 Figure 3-23 Variation of impact force for different barrier heights for MASH TL-5 .............. 69 Figure 3-24 Comparison of contact area between barriers for MASH TL-5 impact. ............... 69 Figure 4-1 Details of a typical section of a BMS model ........................................................ 73 Figure 4-2 Yield surface of the cap model (6) ........................................................................ 75 Figure 4-3 Barrier-moment slab system details for TL-4 analyses ........................................ 77 Figure 4-4 TL-4 SUT vehicle position at each significant moment ....................................... 79 Figure 4-5 TL-4 time history load in the barrier and load distribution. ................................. 80 Figure 4-6 Displacement of the barriers and the moment slab for TL-4 impact .................... 81 Figure 4-7 Barrier-moment slab system details for TL-5-1 analyses ..................................... 83 Figure 4-8 TL-5-1 tractor-trailer vehicle position at each significant moment ...................... 84 Figure 4-9 TL-5 time history load in the barrier and load distribution on the 42 in. (1.07 m) BMS system ........................................................................................... 85 Figure 4-10 Displacement of the barriers and the moment slab for TL-5-1 impact ................. 86 Figure 4-11 Barrier-moment slab system details for TL-5-2 analyses ..................................... 88 Figure 4-12 TL-5-2 tractor-trailer vehicle position at each significant moment ...................... 89 Figure 4-13 TL-5 time history load in the barrier and load distribution on the 48-in. (1.22 m) tall BMS system ..................................................................................... 90 Figure 4-14 Displacement of the barriers and the moment slab for TL-5-2 impact ................. 92 Figure 4-15 Detail of the rotation points on the barrier-moment slab system .......................... 94 Figure 4-16 Load distribution and application point of the quasi-static FE models ................ 95 Figure 4-17 Result of the quasi-static FE analyses for the barrier-moment slab system ......... 96 Figure 4-18 Displacement vector during rotation of the barrier system ................................... 98 Figure 5-1 Components of the MSE wall model .................................................................. 103 Figure 5-2 Precast concrete panel details ............................................................................. 104 Figure 5-3 TL-4 MSE wall model with different soil reinforcement lengths ....................... 107 Figure 5-4 Rebar detail in the barrier and panel for TL-4 impact ........................................ 108 Figure 5-5 Elevation view of the MSE wall showing the strip distribution (TL-4 Impact) ................................................................................................................ 109 Figure 5-6 Time history of MASH TL-4 impact load on barriers (50-msec. average) ........ 109 Figure 5-7 Damage to the 42-in. (1.07 m) tall concrete barrier (TL-4) ................................ 110 Figure 5-8 Displacement of the 42 in. (1.07 m) at IP for TL-4 impact ................................ 111 Figure 5-9 Time-history of the total load in the maximum stressed strips (TL-4) ............... 113 Figure 5-10 Distribution of the total load at section B6-C-1st (TL-4) .................................... 114 Figure 5-11 Displacements of the wall panels (TL-4) ............................................................ 115 Figure 5-12 Elevation view of the MSE wall showing the strip distribution (TL-5 Impact) ................................................................................................................ 116

x Figure 5-13 Rebar detail in the barrier and panel for TL-5-1 impact ..................................... 117 Figure 5-14 TL-5 MSE wall model showing the profile of the 42-in.. (1.07 m) tall barrier and embedded soil strip ........................................................................... 118 Figure 5-15 Time history of MASH TL-5-1 impact load on barriers (50-msec. average) ..... 119 Figure 5-16 Damage to the 42-in. (1.07 m) tall concrete barrier (TL-5-1) ............................ 120 Figure 5-17 Displacement of the 42 in. (1.07 m) at IP for TL-5-1 ......................................... 121 Figure 5-18 Time-history of the total load in the maximum stressed strips (TL-5-1) ............ 123 Figure 5-19 Distribution of the total load at section B3-E-1st and B3-D-1st (TL-5-1) ........... 124 Figure 5-20 Damage profile of the panel at B3 (below IP) for TL-5-1 impact ...................... 125 Figure 5-21 Displacements at the wall panels (TL-5-1) ......................................................... 125 Figure 5-22 Rebar detail in the barrier and panel for TL-5-2 impact ..................................... 127 Figure 5-23 TL-5 MSE wall model showing the profile of the 48-in. (1.22 m) tall barrier and embedded soil strips ..................................................................................... 128 Figure 5-24 Time history of MASH TL-5-2 impact load on barriers (50-msec. average) ..... 129 Figure 5-25 Damage to the 48-in. (1.22 m) tall concrete barrier (TL-5-2) ............................ 130 Figure 5-26 Displacement of the 48 in. (1.22 m) barrier for TL-5-2 impact .......................... 131 Figure 5-27 Displacement for TL-5-2 impact with 12 ft (3.66 m) moment slab and 16 ft (4.88 m) long reinforcing strips .......................................................................... 132 Figure 5-28 Time-history of the total load in the maximum stressed strips (TL-5-2) ............ 134 Figure 5-29 Distribution of the total load (TL-5-2) ................................................................ 136 Figure 5-30 Displacements at the wall panels (TL-5-2) ......................................................... 137 Figure 6-1 RECO Single Slope shape concrete barrier details ............................................. 140 Figure 6-2 Overall Layout of the TL-4 MSE wall installation showing CIP ....................... 141 Figure 6-3 Side view of the TL-4 test wall installation with 36-in. (0.91 m) tall barrier ..... 141 Figure 6-4 TL-4 barrier-moment slab system model of the TL-4 test installation ............... 143 Figure 6-5 System reaction force of the TL-4 MSE wall test installation model ................. 144 Figure 6-6 Downstream view of the TL-4 MSE wall model ................................................ 144 Figure 6-7 TL-4 MSE wall and SUT vehicle model ............................................................ 145 Figure 6-8 Vehicle position at each significant time for the test wall installation model .... 146 Figure 6-9 50-msec. average impact load on the single slope TL-4 barrier ......................... 147 Figure 6-10 Moment slab reinforcement ................................................................................ 148 Figure 6-11 Casting of moment slab ...................................................................................... 148 Figure 6-12 Compaction of fill in layers till ground level ...................................................... 148 Figure 6-13 Three-dimensional view of the installation ......................................................... 148 Figure 6-14 On-Board data acquisition system ...................................................................... 149 Figure 6-15 Instrumented reinforcement strips ...................................................................... 149 Figure 6-16 Targets placed on the barrier and panels ............................................................. 149 Figure 6-17 Measurements for permanent displacement before the test ................................ 149 Figure 6-18 SUT used in the TL-4 crash test ......................................................................... 150 Figure 6-19 Downstream and overhead photographs of the TL-4 crash test ......................... 151 Figure 6-20 Damage in barrier number 4 ............................................................................... 151 Figure 6-21 Post-crash views of the barriers from the traffic side ......................................... 152 Figure 6-22 Crack in the compacted fill over the edge of the moment slab ........................... 152 Figure 6-23 Sign Convention used in data processing ........................................................... 153 Figure 6-24 Acceleration in the x-direction at truck CG ........................................................ 153 Figure 6-25 Acceleration in the y-direction at truck CG ........................................................ 154

xi Figure 6-26 Acceleration in the z-direction at truck CG ........................................................ 154 Figure 6-27 Plot of forces calculated from vehicle accelerations ........................................... 155 Figure 6-28 Plot of resultant force versus time ...................................................................... 155 Figure 6-29 Roll, Pitch and Yaw plot versus time .................................................................. 156 Figure 6-30 Dynamic movement at the barrier top versus time ............................................. 156 Figure 6-31 Locations and labels of the instrumented reinforced strips ................................ 157 Figure 6-32 Force measurements from readings of the strain gages installed on the reinforcement strips ............................................................................................ 158 Figure 7-1 RECO NJ shape concrete barrier details ............................................................. 161 Figure 7-2 TL-5 barrier-moment slab system model of the TL-5 test installation ............... 162 Figure 7-3 System reaction force of the TL-5 MSE wall test installation model ................. 162 Figure 7-4 Downstream view of the TL-5 MSE wall model ................................................ 163 Figure 7-5 TL-5 MSE wall and tractor-van-trailer vehicle model ....................................... 164 Figure 7-6 Elevation view of the test wall installation showing the distribution of the strips .................................................................................................................... 165 Figure 7-7 Vehicle position at each significant time for the test wall installation model .... 166 Figure 7-8 50 msec. average impact load on the NJ barrier ................................................. 167 Figure 7-9 Damage profile of the NJ shape barrier .............................................................. 167 Figure 7-10 Displacement of the NJ shape barrier at the impact ........................................... 168 Figure 7-11 Load for selected strip in the uppermost layer .................................................... 169 Figure 7-12 Load for selected strip in the second layer .......................................................... 170 Figure 7-13 Displacement in the reinforcing strips from the FE model ................................. 171 Figure 7-14 Damage profile of the test wall panel at B3 (below IP) for TL-5-1 impact on a NJ barrier on top of the MSE Wall .................................................................. 172 Figure 7-15 Change in bending moment along section A-A of the wall panel ...................... 172 Figure 7-16 Wall panel displacement from the FE test wall model ....................................... 173 Figure 7-17 Overall layout of the TL-5 MSE wall test installation ........................................ 175 Figure 7-18 Side view of the TL-5 test wall installation with 42-in. (1.07 m) tall barrier ..... 176 Figure 7-19 Full-scale MSE wall test installation and TL-5 crash-test set up ........................ 177 Figure 7-20 Instrumentation in the MSE wall test installation ............................................... 178 Figure 7-21 Particle size distribution curve of the backfill material for TL-5 crash test (46) ...................................................................................................................... 181 Figure 7-22 Modified Proctor curve and stiffness curve of the backfill material for TL-5 crash test (46) ...................................................................................................... 182 Figure 7-23 In-situ density tests conducted in the TL-5 MSE wall test installation .............. 183 Figure 7-24 Selected strips with strain gage location for the TL-5 test wall .......................... 185 Figure 7-25 Test vehicle and test installation geometry ......................................................... 186 Figure 7-26 Barrier and MSE wall installation after TL-5 crash test ..................................... 188 Figure 7-27 Damage to traffic face of TL-5 MSEW after the impact test ............................. 189 Figure 7-28 Field side of TL-5 MSEW after test ................................................................... 190 Figure 7-29 Crack in soil after impact .................................................................................... 191 Figure 7-30 Vehicle damage after impact .............................................................................. 191 Figure 7-31 Summary of results for MASH test 5-12 on the NJ shape barrier on top of the MSE wall....................................................................................................... 193 Figure 7-32 Acceleration data from the tractor-front mounted accelerometer ....................... 194 Figure 7-33 Acceleration data from the tractor-rear mounted accelerometer ........................ 195

xii Figure 7-34 Roll, Pitch and yaw angle measure close to the vehicle fifth wheel ................... 196 Figure 7-35 Acceleration data from the trailer-rear mounted accelerometer ......................... 196 Figure 7-36 Moment slab response during impact ................................................................. 198 Figure 7-37 Location of displacement bars affixed on the barrier and panels. ...................... 199 Figure 7-38 Location indicators for strain gages on the strips. .............................................. 199 Figure 7-39 Dynamic load on the soil reinforcing strips (raw data) ....................................... 201 Figure 7-40 Dynamic load on the soil reinforcing strips (50-msec. average data) ................. 202 Figure 7-41 Dynamic load distribution in the strips by measured .......................................... 204 Figure 7-42 Hair-line crack in the panels after impact ........................................................... 205 Figure 7-43 Sketch of free body diagram of the load transferred into the wall panels .......... 206 Figure 7-44 Reflective targets in the barrier and wall panel to measure permanent deflection............................................................................................................. 207 Figure 7-45 Location of the reflective displacement targets for measurement of permanent deflection ........................................................................................... 208 Figure 7-46 Lateral permanent deflection at the selected targets ........................................... 210 Figure 7-47 Total permanent deflection at the selected targets .............................................. 211 Figure 7-48 Sketch of lateral permanent deflection at the impacted area .............................. 212 Figure 7-49 Structural integrity of the moment slab after impact .......................................... 213 Figure 7-50 Comparison of the full-scale test installation and the full-scale FE model ........ 215 Figure 7-51 Comparison of vehicle position in TL-5 test and simulation .............................. 217 Figure 7-52 Comparison of the tractor-front acceleration between test and simulation ........ 219 Figure 7-53 Comparison of the tractor-rear acceleration between test and simulation .......... 220 Figure 7-54 Comparison of the trailer-rear acceleration between test and simulation ........... 221 Figure 7-55 Comparison of permanent deflection between the test and simulation .............. 222 Figure 7-56 Comparison of panel analyses between test and simulation ............................... 223 Figure 7-57 Comparison of strips loads at the upper most layer of soil reinforcement ......... 224 Figure 7-58 Comparison of strips loads at the second layer of soil reinforcement ................ 225 Figure 8-1 Quasi-static FE analyses set up for the test barrier-moment slab system ........... 229 Figure 8-2 Results of the quasi-static FE analyses in the test barrier-foundation system .... 230 Figure 8-3 Details of the full-scale static test set-up on the barrier-foundation system ....... 231 Figure 8-4 Photograph of the full-scale static test set-up ..................................................... 233 Figure 8-5 Crack in the soil during the static load test ......................................................... 234 Figure 8-6 Results of the full-scale static test on the barrier-foundation system ................. 235 Figure 8-7 Vertical displacement of moment slab and applied static load ........................... 236 Figure 8-8 Time history load of the strip during the static test ............................................ 237 Figure 8-9 Sketch of movement of the barrier system during the static test ........................ 237 Figure 8-10 Relative movement at the bottom of barrier segment 6 and 7 during the during the static test ............................................................................................ 238 Figure 8-11 Relative panel movement observed during the static load test ........................... 239 Figure 8-12 Comparison of static test and FE static model .................................................... 240 Figure 9-1 Rotation points for design of barrier-moment slab system ................................. 242 Figure 9-2 Application of static equivalent load on barrier-moment slab system. ............... 243 Figure 9-3 Coping and possible weakest section. ................................................................. 246 Figure 9-4 Pressure distribution pdp for reinforcement pullout. ........................................... 248 Figure 9-5 Default values for the pullout friction factor, F* (AASHTO LRFD Figure11.10.6.3.2-1) (3). ..................................................................................... 249

xiii Figure 9-6 Line Load Qdp for reinforcement pullout. ........................................................... 250 Figure 9-7 Pressure distribution pd for reinforcement yield ................................................. 252 Figure 9-8 Line Load Qdy for reinforcement yield. .............................................................. 253 Figure 9-9 Locations of displacement measurements .......................................................... 259 Figure 9-10 Difference in dynamic displacements at the barrier top for the same angle of rotation ................................................................................................................ 260 Figure 9-11 Barrier displacements at the top level of the adopted barrier-moment slab systems for static load calculations ..................................................................... 260 Figure 9-12 Barrier displacements at coping level of adopted barrier-moment slab systems for static load calculations ..................................................................... 261 Figure 9-13 TL3 (3 in) Impact Load versus Time .................................................................. 263 Figure 9-14 Maximum displacements at the top of the barrier versus time for TL-3 Impact Levels with moment slab widths 3.5, 4.0 and 4.5 ft ............................... 264 Figure 9-15 Maximum displacements at the coping level of the barrier versus time for TL-3 Impact Levels with moment slab widths 3.5, 4.0 and 4.5 ......................... 264 Figure 9-16 TL-3 Barrier-moment slab system used in the calculation of resistance against sliding and overturning ........................................................................... 265 Figure 9-17 TL-4-1 Impact Load versus Time for 36 in. (0.91 m) barrier ............................. 269 Figure 9-18 TL4-2 Impact Load versus Time for 42 in. (1.07 m) barrier .............................. 270 Figure 9-19 Maximum displacements at the top of the barrier versus time for TL-4-1 Impact Levels with moment slab widths 4.0, 4.5 and 5.2 ft ............................... 271 Figure 9-20 Maximum displacements at the coping level of the barrier versus time for TL-4-1 Impact Levels with moment slab widths 4.0, 4.5 and 5.2 ft ................... 271 Figure 9-21 Maximum displacements at the top level of the barrier versus time for TL-4-1 and TL-4-2 Impact Levels with 4.5 ft moment slab width ..................... 272 Figure 9-22 Maximum displacements at the coping level of the barrier versus time for TL-4-1 and TL-4-2 Impact Levels with 4.5 ft moment slab width. .................... 273 Figure 9-23 TL-4-1 barrier-moment slab system used in the calculation of resistance against sliding and overturning ........................................................................... 273 Figure 9-24 TL-4-2 Barrier-moment slab system used in the calculation of resistance against sliding and overturning ........................................................................... 274 Figure 9-25 TL5-1 (42 in) Impact Load versus Time ............................................................. 279 Figure 9-26 Maximum Displacements obtained at the top of a barrier of TL5-1 tested NJ Barrier and a straight barrier versus Time .......................................................... 280 Figure 9-27 Maximum Displacements obtained at the coping level of a barrier of TL5-1 tested NJ Barrier and a straight barrier versus Time ........................................... 281 Figure 9-28 Barrier-moment slab system used in the calculation of resistance against sliding and overturning ....................................................................................... 282 Figure 9-29 TL5-2 (48 in) Impact Load versus Time ............................................................. 287 Figure 9-30 Maximum Displacements obtained at the top of a barrier of TL-5-2 tested straight barriers ................................................................................................... 288 Figure 9-31 Maximum Displacements obtained at the coping level of a barrier of TL-5-2 tested straight barriers ......................................................................................... 288 Figure 9-32 TL-5-2 Barrier-moment slab system used in the calculation of resistance against sliding and overturning ........................................................................... 289

xiv LIST OF TABLES Table 1-1 MASH designation and impact conditions (5)........................................................ 5 Table 2-1 Comparison between LRFD factors and ASD factors for designing MSE wall. ....................................................................................................................... 16 Table 2-2 Vehicle description incorporated in NCHRP Report 350 and MASH (4-5). ....... 18 Table 2-3 Summary of the TL-4 crash tests .......................................................................... 21 Table 2-4 Summary of full-scale crash test conducted with tractor-trailer vehicles ............. 24 Table 2-5 Summary of the instrumented wall test program with tractor trailers (13) ........... 28 Table 2-6 Summary of the stability tests, bogie tests, and full-scale crash test conducted under NCHRP Project 22-20 (2). ........................................................ 36 Table 3-1 Summary of magnitude, distribution and application of the MASH TL-4 impact loads .......................................................................................................... 55 Table 3-2 Computation of impact dynamic forces using the equation of motion ................. 59 Table 3-3 Summary of magnitudes, distributions and applications of dynamic loads for MASH TL-5 impact ........................................................................................ 68 Table 3-4 Recommended design loads for TL-4 and TL-5 impact ....................................... 70 Table 4-1 Soil cap material properties used in the simulation (2) ......................................... 76 Table 4-2 Summary of the static forces using equilibrium equation .................................... 94 Table 4-3 Comparison between analytical solution and FE analyses ................................... 97 Table 5-1 Summary of the full-scale impact simulation for TL-4 and TL-5 ...................... 100 Table 5-2 Unfactored resistance and force in the reinforcing strips for TL-5 MSE wall ... 102 Table 5-3 Summary of the impact loads and barrier displacements for the MASH TL-4 impact simulation ....................................................................................... 110 Table 5-4 Summary of the total load for the selected strip location (TL-4 impact) ............ 112 Table 5-5 Summary of the impact loads and barrier displacements for the MASH TL-5-1 impact simulation ................................................................................... 120 Table 5-6 Summary of the total load for the selected strip location (TL-5-1impact) ......... 122 Table 5-7 Summary of the impact loads and barrier displacements for the MASH TL-5-2 impact simulations .................................................................................. 130 Table 5-8 Summary of the total load for the selected strip location (TL-5-2 impact) ........ 133 Table 6-1 Pullout unfactored resistance and force in the reinforcing strips for TL-4 MSE wall ............................................................................................................ 142 Table 7-1 Pullout unfactored resistance and force in the reinforcing strips for TL-5-1 MSE wall ............................................................................................................ 160 Table 7-2 Gradation limits for TxDOT type A and B select backfill (48) .......................... 179 Table 7-3 Select index properties of the backfill soil material (46) .................................... 180 Table 7-4 Summary of the in-situ nuclear density tests and BCD modulus tests ............... 184 Table 7-5 Measured dynamic loads on the soil reinforcing strips ...................................... 200 Table 7-6 Static load on the soil reinforcing strips ............................................................. 203 Table 7-7 Total loads on the soil reinforcing strips ............................................................. 203 Table 7-8 Results of permanent deflection measurements .................................................. 209 Table 7-9 Performance evaluation summary for MASH Test 5-12 on the MSE Wall ....... 214 Table 7-10 Comparisons between measured and simulated displacement in the barriers .... 222 Table 8-1 Results of the analytical solution of the TL-5 test barrier-moment slab system ................................................................................................................. 228 Table 9-1 Recommended equivalent static load (Ls) for TL-3 through TL-5 ..................... 244

xv Table 9-2 Design pressure pdp for reinforcement pullout and tributary height ................... 247 Table 9-3 Design line load Qdp for reinforcement pullout .................................................. 250 Table 9-4 Design pressure pdy for reinforcement yield ...................................................... 251 Table 9-5 Design line load Qd for reinforcement yield ....................................................... 253 Table 9-6 Summary of crash test barrier and simulation displacement results ................... 258 Table 9-7 Selected moment-slab system for static load calculations .................................. 262 Table 9-8 Simulation results and calculation of TL-3 design strip load for pullout ........... 267 Table 9-9 TL-3 design pressure for yielding of soil reinforcement based on bogie test results .................................................................................................................. 268 Table 9-10 Summary of the pullout resistance, maximum 50-msec. average strip load and wall displacement for MASH TL-4 impact simulation ................................ 276 Table 9-11 Simulation results and calculation of TL-4 design strip load for pullout ........... 277 Table 9-12 Simulation results for TL-4 impact and calculation of design strip load for yielding design .................................................................................................... 278 Table 9-13 TL-4 design pressure for yielding of soil reinforcement based on simulation results .................................................................................................................. 279 Table 9-14 Summary of the pullout resistance, maximum 50-msec. average strip load and wall displacement for MASH TL-5-1 impact simulation ............................ 283 Table 9-15 Summary of the dynamic design load on the strips for pullout resistance from the MASH TL-5-1 full-scale impact test ................................................... 283 Table 9-16 Test results of the TL-5-1 impact and calculation of design strip load for pullout design ...................................................................................................... 284 Table 9-17 Simulation results for TL-5-1 impact and calculation of design strip load for yielding design .................................................................................................... 285 Table 9-18 TL-5-1 design pressure for yielding of soil reinforcement ................................. 286 Table 9-19 Summary of the pullout resistance, maximum 50-msec. average strip load and wall displacement for MASH TL-5-2 impact simulation ............................ 290 Table 9-20 Simulation results of the TL-5-2 impact and calculation of design strip load for pullout design ................................................................................................ 291 Table 9-21 Simulation results for TL-5-2 impact and calculation of design strip load for yielding design .................................................................................................... 292 Table 9-22 TL-5-2 design pressure for yielding of soil reinforcement ................................. 293

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Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls Get This Book
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A major use of Mechanically Stabilized Earth (MSE) walls is as bridge approach embankments, where they are typically constructed with a roadside barrier system supported on the edge of the walls.

The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 326: Design Guidelines for Test Level 3 through Test Level 5 Roadside Barrier Systems Placed on Mechanically Stabilized Earth Retaining Walls is dedicated to developing guidelines for barrier-moment slab systems placed over MSE walls to resist vehicular impact loads resulting from three test levels.

Supplementary to the document is a Presentation.

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