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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Criteria for Restoration of Longitudinal Barriers, Phase II. Washington, DC: The National Academies Press. doi: 10.17226/26321.
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NCHRP Web-Only Document 304 Criteria for Restoration of Longitudinal Barriers, Phase II Chuck A. Plaxico Malcolm H. Ray Christine E. Carrigan T. Olaf Johnson Archie Ray RoadSafe LLC Canton, ME Contractor’s Final Report for NCHRP Project 22-28 Submitted June 2015 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 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 304 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs David Jared, Senior Program Officer Clara Schmetter, Senior Program Assistant Natalie Barnes, Director of Publications Kathleen Mion, Senior Editorial Assistant NCHRP PROJECT 22-28 Panel Field of Design—Area of Vehicle Barrier Systems Bernie L. Clocksin, South Dakota DOT, Pierre, SD (Chair) (retired) Michael S. Bline, Office of Licking County (OH) Engineer, Newark, OH D. Lance Bullard, Jr., Texas A&M Transportation Institute, College Station, TX Mark Burkhead, Harrisburg, PA Scott Gardner Capps, North Carolina DOT, Raleigh, NC Douglas Gabauer, Bucknell University, Lewisburg, PA Armando Garcia, Coffman Specialties, Inc., San Diego, CA David L. Little, Iowa DOT, Mason City, IA Eduardo Arispe, FHWA Liaison Nicholas Artimovich, II, FHWA Liaison James Bryant, Jr., TRB Liaison

i CONTENTS Chapter 1 – Introduction ................................................................................................................. 1 Project Objective .................................................................................................................... 1 Background ............................................................................................................................ 2 Roadmap of the Report .......................................................................................................... 4 Chapter 2 – A Summary of Common Non-Proprietary Guardrails (Basic Design and Crash Performance) ................................................................................................................................... 6 Crash Testing for Federal Aid Eligibility .............................................................................. 6 Summary of Common Non-Proprietary Strong-Post Guardrail Systems .............................. 7 Modified G4(1S) with Routed Wood Blockouts ............................................................. 7 G4(2W) .......................................................................................................................... 13 G4(1W) .......................................................................................................................... 15 MGS ............................................................................................................................... 15 MGS with Round Wood Posts ....................................................................................... 16 G9 Thrie-Beam Guardrail .............................................................................................. 17 Thrie-Beam Guardrail with Wood Blockouts ................................................................ 21 Modified Thrie-Beam Guardrail .................................................................................... 21 Summary of Full-Scale Tests Conducted on Strong-Post Guardrail ............................. 23 Typical System Damage in Low-Speed Full-Scale Tests .................................................... 23 Chapter 3 – Literature Review ...................................................................................................... 28 General Crash Phenomena that Lead to Poor Performance ................................................. 28 Pocketing........................................................................................................................ 28 Wheel Snag .................................................................................................................... 29 Barrier Override ............................................................................................................. 29 Rail Rupture ................................................................................................................... 30 General Functions and Influences of Guardrail Components .............................................. 30 Posts and Soil ................................................................................................................. 30 Blockouts ....................................................................................................................... 47 Rail-to-Post Connection ................................................................................................. 54

ii Rail Element................................................................................................................... 57 End Terminals ................................................................................................................ 64 Summary of Literature Review ............................................................................................ 68 Chapter 4 – Survey of Practice ..................................................................................................... 69 Chapter 5 – Prioritization of Damage Modes ............................................................................... 71 Introduction .......................................................................................................................... 71 Methods for Evaluating Damage Modes ............................................................................. 71 Full-Scale Testing .......................................................................................................... 71 Pendulum Testing .......................................................................................................... 72 Computer Simulation ..................................................................................................... 72 Guardrail Systems ................................................................................................................ 73 Critical Damage Modes ....................................................................................................... 73 G4(1W) and G4(2W) Wood-Post W-Beam Guardrails ................................................. 75 Thrie-Beam Steel Post Guardrail ................................................................................... 85 Modified Thrie-Beam Guardrail .................................................................................... 90 MGS – Steel Post W-Beam Guardrail ........................................................................... 92 G2 – Weak-Post W-Beam Guardrail ............................................................................. 95 End Terminals ................................................................................................................ 96 Guardrail Transitions ..................................................................................................... 99 Combination Damage Modes .............................................................................................. 99 Combination of Post and Rail Deflection and Rail-to-Post Connection ........................ 99 Combination of Rail Deflection and Splice Damage ................................................... 100 Combination of Post and Rail Deflection and Anchor Damage .................................. 100 Combination of Post/Rail Deflection and Missing Post(s) .......................................... 101 Other Considerations ......................................................................................................... 101 Traffic Exposure .......................................................................................................... 101 Evaluating Impact Upstream or Downstream of Damaged Section: ........................... 101 Hazard Being Shielded ................................................................................................ 101 Recommendations .............................................................................................................. 102 Chapter 6 – General Research Approach ................................................................................... 105 Finite Element Analysis ............................................................................................... 105 Pendulum Testing ........................................................................................................ 108 Chapter 7 – Development and Validation of the G4(2W) Guardrail Model .............................. 109 Model Development........................................................................................................... 109

iii W-Beam ....................................................................................................................... 109 Splice Connection Model ............................................................................................. 111 Bolt Hardware .............................................................................................................. 113 Guardrail Posts ............................................................................................................. 114 Soil Model .................................................................................................................... 118 Vehicle Model .............................................................................................................. 126 Validation of the G4(2W) Guardrail Model ...................................................................... 126 Simulation of Test 471470-26 ..................................................................................... 126 Qualitative Validation .................................................................................................. 129 Quantitative Validation ................................................................................................ 143 Conclusions ........................................................................................................................ 154 Chapter 8 – Evaluation of Guardrail Post Deterioration for the G4(2W) ................................... 155 Scope .................................................................................................................................. 156 Procurement of Guardrail Post Test Articles ..................................................................... 156 Resistograph Measurements and Processing ..................................................................... 157 Resistograph Measurements ........................................................................................ 157 Data Processing and Interpretation .............................................................................. 157 Statistics for Resistograph Measurement of Test Articles ........................................... 161 Pendulum Testing of Post-in-Rigid-Foundation ................................................................ 163 Scope ............................................................................................................................ 163 Test Specimen Mounting Condition ............................................................................ 167 Equipment and Instrumentation ................................................................................... 168 Impact Conditions ........................................................................................................ 170 Results .......................................................................................................................... 171 Correlation of Resistograph Measurements to Test Results .............................................. 174 Quantifying Wood Post Deterioration Damage Levels ..................................................... 186 Visual and Auditory Cues ............................................................................................ 191 Pendulum Testing of Posts-in-Soil .................................................................................... 191 Scope ............................................................................................................................ 191 Soil Strength Tests ....................................................................................................... 194 Wood Post Strength Test ............................................................................................. 196 Effects of Post Shape (Round vs. Rectangular) on Load Capacity .............................. 196 Finite Element Analysis ..................................................................................................... 200 Calibration of FE Models for Deteriorated Posts ........................................................ 200

iv Evaluate Effects of Post Deterioration on Guardrail Performance .............................. 212 Summary and Discussion ................................................................................................... 226 Recommendations .............................................................................................................. 228 Chapter 9 – Effects of Anchor Strength on Performance of the G4(2W) ................................... 230 Research Approach ............................................................................................................ 231 Physical Testing ................................................................................................................. 232 Quasi-Static Pull-Test on End-Anchor ........................................................................ 232 Evaluate Effects of Anchor Strength on Guardrail Performance ....................................... 240 Results .......................................................................................................................... 241 Summary and Discussion ................................................................................................... 251 Recommendations .............................................................................................................. 254 Chapter 10 – Combination Damage Mode of Rail Deflection and Rail-Post Connection for the G4(2W) ....................................................................................................................................... 255 Evaluate Effects of Rail Deflection and Rail-to-Post Connection Strength ...................... 255 Low Severity Crash-Induced Damage ......................................................................... 255 High-Speed Impact into Pre-Damaged Guardrail ........................................................ 259 Summary and Discussion ................................................................................................... 266 Recommendations .............................................................................................................. 269 Chapter 11 – Re-Assess Cause of Failure in Test C08C3-027 for the Modified G4(1S) with Pre- Crash-Induced Deflection. ........................................................................................................... 271 Simulation of Test C08C3-027-1 ....................................................................................... 272 Test C08C3-027-1 Summary ....................................................................................... 272 FEA Model Development ............................................................................................ 273 FEA Simulation ........................................................................................................... 275 Simulation of Test C08C3-027-2 ....................................................................................... 279 Test C08C3-027-2 Summary ....................................................................................... 279 Model Setup – Including Pre-Damage ......................................................................... 279 FEA Simulation ........................................................................................................... 280 Summary and Discussion ................................................................................................... 299 Conclusions ........................................................................................................................ 301 Recommendations .............................................................................................................. 302 Chapter 12 – Effects of Soil Erosion at Guardrail Posts for the G4(2W) ................................... 303 Research Approach ............................................................................................................ 304 Physical Testing ................................................................................................................. 304 Equipment and Instrumentation ................................................................................... 307 Impact Conditions ........................................................................................................ 308 Results .......................................................................................................................... 309

v Finite Element Analysis ..................................................................................................... 315 Calibration/Validation of FE Soil-Erosion Model ....................................................... 315 Effects of Soil Erosion on Guardrail Performance ...................................................... 326 Summary and Discussion ................................................................................................... 337 Recommendations .............................................................................................................. 338 Chapter 13 – Anchor Strength Quantified in Terms of Anchor Damage ................................... 340 Research Approach ............................................................................................................ 341 Test Set-up ................................................................................................................... 342 Equipment and Instrumentation ................................................................................... 347 Test Procedure ............................................................................................................. 349 Test Results ........................................................................................................................ 350 Missing or Non-Functioning Groundline Strut ............................................................ 354 Reduced Embedment Depth ........................................................................................ 356 Slack Anchor-Cable ..................................................................................................... 363 Summary and Discussion ................................................................................................... 368 Discussion of Failure Modes ....................................................................................... 368 Missing Groundline Strut ............................................................................................. 369 Reduced Embedment Depth for the Foundation Tubes ............................................... 369 Slack in Anchor Cable ................................................................................................. 371 Recommendations .............................................................................................................. 371 Future Work ................................................................................................................. 373 Chapter 14 – Effects of W-Beam Splice Damage on Rail Capacity ........................................... 375 Research Approach ............................................................................................................ 375 Procurement and Assessment of Damaged W-Beam Splices ............................................ 376 Inspection of Fully Assembled Splice (General Field-Type Measurements) .............. 376 Inspection of Unassembled Splice (for Hidden Damages in the Splice-Holes) .......... 387 Physical Testing ................................................................................................................. 387 Equipment and Instrumentation ................................................................................... 387 Test Setup..................................................................................................................... 389 Impact Conditions ........................................................................................................ 393 Scope ............................................................................................................................ 393 Results .......................................................................................................................... 395 Discussion of Test Results ................................................................................................. 406 Rail Flattening .............................................................................................................. 406 Longitudinal Displacement (Slip) in the Splice Connection ....................................... 407

vi Vertical Crush .............................................................................................................. 408 Lateral Separation of Rails at Splice ............................................................................ 408 Conclusions ........................................................................................................................ 408 Recommendations .............................................................................................................. 409 Chapter 15 – Development of Field Guide Materials and Field Testing .................................... 411 The Field Manual ............................................................................................................... 411 Online Interactive Field Guide ........................................................................................... 412 Chapter 16 – Field Guide Application Examples ....................................................................... 417 Example 1 .......................................................................................................................... 418 User Input for Question 1: ........................................................................................... 418 User Input for Question 2: ........................................................................................... 419 User Input for Question 3: ........................................................................................... 419 User Input for Question 4: ........................................................................................... 419 User Input for Question 5: ........................................................................................... 420 User Input for Question 6: ........................................................................................... 420 User Input for Question 7: ........................................................................................... 420 User Input for Question 8: ........................................................................................... 421 User Input for Question 9: ........................................................................................... 421 User Input for Question 10: ......................................................................................... 421 User Input for Question 11: ......................................................................................... 422 User Input for Question 12: ......................................................................................... 422 User Input for Question 13: ......................................................................................... 422 User Input for Question 14: ......................................................................................... 423 User Input for Question 15: ......................................................................................... 423 Assessment Results: ..................................................................................................... 424 Example 2 .......................................................................................................................... 425 User Input for Question 1: ........................................................................................... 425 User Input for Question 2: ........................................................................................... 426 User Input for Question 3: ........................................................................................... 426 User Input for Question 4: ........................................................................................... 426 User Input for Question 5: ........................................................................................... 427 User Input for Question 6: ........................................................................................... 427 User Input for Question 7: ........................................................................................... 427

vii User Input for Question 8: ........................................................................................... 428 User Input for Question 9: ........................................................................................... 428 User Input for Question 10: ......................................................................................... 428 User Input for Question 11: ......................................................................................... 429 User Input for Question 12: ......................................................................................... 429 User Input for Question 13: ......................................................................................... 429 User Input for Question 14: ......................................................................................... 430 User Input for Question 15: ......................................................................................... 430 User Input for Question 16: ......................................................................................... 430 User Input for Question 17: ......................................................................................... 431 Assessment Results: ..................................................................................................... 432 Example 3 .......................................................................................................................... 433 User Input for Question 1: ........................................................................................... 433 User Input for Question 2: ........................................................................................... 434 User Input for Question 3: ........................................................................................... 434 User Input for Question 4: ........................................................................................... 434 User Input for Question 5: ........................................................................................... 435 Assessment Results: ..................................................................................................... 436 Chapter 17 – Conclusions ........................................................................................................... 437 Damage Modes Investigated .............................................................................................. 437 Recommendations for Future Work................................................................................... 438 Recommendations for Additional Barrier Types ............................................................... 439 REFERENCES ........................................................................................................................... 440 LIST OF FIGURES Figure 1. Modified G4(1S) with wood blockouts.[Bullard96] ........................................................ 8 Figure 2. Sequential views of Crash Test 405421-1.[Bullard96] .................................................... 8 Figure 3. Sequential views of Crash Test 2214-WB2.[Polivka06b] ................................................ 8 Figure 4. Sequential views of Crash Test 2214-WB1.[Polivka06b] ................................................ 8 Figure 5. Drawing of the strong-post w-beam guardrail (SGR04a-c). ............................................. 9 Figure 6. Drawing of the 8-inch wood blockout for the modified G4(1S) with wood blockout guardrail (PDB01b). ..................................................................................................... 10

viii Figure 7. Drawing of the W6x9 guardrail post (PWE01). ............................................................. 11 Figure 8. Drawing of the bolt used to fasten the rail element to guardrail posts. .......................... 12 Figure 9. Photo of the G4(2W) guardrail Test 476460-1-5 test installation.[Bullard10] .............. 13 Figure 10. Sequential views of full-scale crash Test 471470-26.[Mak99] ..................................... 13 Figure 11. Sequential views of full-scale crash Test RF476460-1-5.[Bullard10] ......................... 13 Figure 12. Drawing of the rectangular wood post used in the G4(2W) and G4(1W) guardrail systems (i.e., AASHTO designator SGR04b). ............................................................. 14 Figure 13. Photo of the MGS guardrail system. [Sicking02] ......................................................... 16 Figure 14. MGS with (a) 7.25-inch diameter round Douglas Fir posts and (b) 8-inch diameter round Ponderosa Pine posts. ........................................................................................ 16 Figure 15. Test MGSDF-1 of the MGS guardrail with 7.25-inch diameter Douglas Fir posts. [Hascal07] .................................................................................................................... 17 Figure 16. Test MGSPP-1 of MGS with 8-inch diameter Ponderosa Pine posts. [Hascal07] ....... 17 Figure 17. Photo of the standard thrie-beam guardrail (G9; SGR09a) .......................................... 18 Figure 18. Sequential photos of Test 471470-31 on the G9 thrie-beam guardrail. [Mak99] ......... 18 Figure 19. AASHTO-AGC-ARTBA drawings for the SGR09 guardrail systems. [AASHTO04] . 19 Figure 20. AASHTO-AGC-ARTBA drawings for the W6x9 steel blockout for the G9 thrie-beam guardrail.[AASHTO04] ................................................................................................. 20 Figure 21. Photo of the thrie-beam guardrail with routed wood blockouts. [Bullard10] .............. 21 Figure 22. Sequential photos for Test 476460-1-8 on the thrie-beam guardrail with routed wood blockouts (MASH Test 3-11).[Bullard10] ................................................................... 21 Figure 23. Photo of the modified thrie-beam guardrail (SGR09b). ............................................... 22 Figure 24. Sequential photos for Test 471470-30 on the modified thrie-beam guardrail (SGR09b) under NCHRP Report 350 Test 3-11 conditions. [Mak99] .......................................... 22 Figure 25. Sequential photos for Test 404211-5a on the modified thrie-beam guardrail under NCHRP Report 350 Test 4-12 conditions.[Buth99c] ................................................... 22 Figure 26. AASHTO-AGC-ARTBA drawings for the M14x17.2 steel blockout for the modified thrie-beam guardrail.[AASHTO04] .............................................................................. 24 Figure 27. Low-speed Test C08C3-027.1 on the modified G4(1S) with routed wood blockouts. [Fleck08] ...................................................................................................................... 27 Figure 28. Barrier deflections recorded after Test C08C3-027.1. [Fleck08] ................................. 27 Figure 29. Guardrail damage in Test C08C3-027.1. [Fleck08] ..................................................... 27 Figure 30. Example of pocketing during a simulated impact with a w-beam median barrier. [Fang10] ....................................................................................................................... 29 Figure 31. Modified Eccentric Loader Breakaway Cable Terminal. [Patzner99] .......................... 32 Figure 32. Illustration of wood post with failure fuse. ................................................................... 35

ix Figure 33. Summary of TTI Test 0482-1 on the G4(2W) with 12.5-ft post spacing. [Mak93] .... 37 Figure 34. Maximum rail tension as a function of missing posts.[Gabler10] ............................... 38 Figure 35. Maximum dynamic deflection comparison plots: (a) KSWB-1, (b) KSWB-2, (c) KSWB-3, (d) KSWB-4. [Rosson96] ............................................................................ 43 Figure 36. Typical steel post test installation for bogie impact testing.[Polivka00b] ..................... 44 Figure 37. W-beam guardrail adjacent to 2:1 foreslope for full-scale crash test.[Polivka00b] ...... 46 Figure 38. Illustration of how blockouts help reduce possibility of wheel-snag.[Ray04].............. 47 Figure 39. Wheel snag against guardrail post in TTI Test 471470-26.[Mak94] ............................. 48 Figure 40. Illustration of how blockouts help to maintain critical rail height during post deflection. ..................................................................................................................... 49 Figure 41. Peak tire-post impact force as a function of blockout depth for Report 350 TL-3 impacts.[Karlsson00] ................................................................................................... 49 Figure 42. Modified thrie-beam guardrail (SGR09b).[Sheikh09] ................................................... 52 Figure 43. Deformation of thrie-beam guardrail during impact with 4,577-lb vehicle at 85 mph and 25 degree impact.[Sheikh09] ................................................................................. 53 Figure 44. Position of bolt in slotted hole in w-beam for each load case.[Plaxico03]................... 56 Figure 45. Results from uniaxial tests on rail-to-post connections.[Plaxico03] ............................ 56 Figure 46. Effective plastic strains in the back layer of w-beam in a guardrail splice showing the formation of a plastic hinge. [Ray01b] ......................................................................... 58 Figure 47. Von Mises stress contour plot showing relatively low stresses on the top layer of rail in the rail splice.[Ray01b] ................................................................................................ 58 Figure 48. Pendulum test setup for the Gabler et al. study. [Gabler10] ........................................ 59 Figure 49. Fabricated splice damage mode evaluated by Gabler et al. [Gabler10] ....................... 60 Figure 50. Test 473750-1 on a weak-post w-beam guardrail resulting in rail rupture. [Buth00a] 62 Figure 51. Sequential view of Report 350 Test 3-11 on the modified G2 at 32.25 inch rail height.[Buth00c]........................................................................................................... 63 Figure 52. Sequential view of Report 350 Test 3-10 on the modified G2 at 32.25 inch rail height.[Buth00e] ........................................................................................................... 63 Figure 53. FEA results for Report 350 Test 3-11 on the G4(1S) guardrail with rail heights of (a) 27 inches, (b) 25.5 inches and (c) 24 inches.[Marzougui07a] ..................................... 63 Figure 54. Full-scale test results for Report 350 Test 3-11 on the G4(1S) guardrail with rail heights of (a) 27 inches and (b) 24.5 inches.[Marzougui07a] ..................................... 64 Figure 55. Sketch of typical guardrail anchor system. .................................................................... 65 Figure 56. Generic end-terminal used in full-scale Crash Test 2214-WB1 of a strong-post guardrail system.[Polivka06a] ..................................................................................... 65

x Figure 57. Test results for Test NEC-1 on modified G4(1S) with wood blockouts and 4-inch curb. [Polivka00a] ................................................................................................................. 66 Figure 58. Guardrail damage in Test TTI 404201-1.[Bullard00] .................................................. 67 Figure 59. Typical damage modes for wood post guardrails.[Bullard00;Mak95] ......................... 75 Figure 60. Typical damage mode for steel wide-flange posts.[Fleck08b] ..................................... 75 Figure 61. Post-test photo for Test MGA C08C3-027.2 showing the un-failed rail-post connection which resulted in the post pulling the rail down during impact.[Fleck08b] ................ 76 Figure 62. Post-test photo for Test MGA C08C3-027.2 showing the excessive anchor movement that occurred during the test.[Fleck08b] ...................................................................... 77 Figure 63. Post fracture below groundline due to rot. [Photo provided by Mark Bloshock] ......... 78 Figure 64. Illustration of possible splice deformation mode resulting from a split blockout. ....... 81 Figure 65. Blockout split during Test NEC-1 (left) and in Test 405160-1-1 (right).[Polivka00a; Buth06] ......................................................................................................................... 81 Figure 66. Splice damage mode investigated in Report 656.[Gabler10] ....................................... 84 Figure 67. Splice rupture initiated at downstream splice bolts in (a) Test NEC-1, (b) Test 405160- 1-1 and (c) Test C08C3-027.1. [Polivka00a; Buth06; MGA08b] ................................ 84 Figure 68. Effective plastic strain contour plot at a splice connection. [Ray01b] .......................... 85 Figure 69. Photo of the standard thrie-beam guardrail. .................................................................. 87 Figure 70. Flow chart for developing damage assessment criteria for the G4(2W) and the generic end-terminal. .............................................................................................................. 106 Figure 71. Flow chart for developing damage assessment criteria for the G4(1S). ..................... 107 Figure 72. Finite element model of the G4(2W) guardrail........................................................... 110 Figure 73. Angle perspective view illustrating typical components of guardrail model. ............ 110 Figure 74. Components of the finite element model of a weak-post w-beam guardrail splice used in Ray et al. [Ray01a] ................................................................................................ 112 Figure 75. Splice connection model used in current study. ......................................................... 112 Figure 76. Test setup and axial force-displacement graphs from uniaxial tension tests of guardrail splices. [Engstrand00] ............................................................................................... 113 Figure 77. Test set-up and FEA model used in wood-model validation. ..................................... 117 Figure 78. Force vs. deflection plots from dynamic impact tests 13009K and 13009L at impact speed of 20 mph. ........................................................................................................ 117 Figure 79. Energy vs. deflection plots from dynamic impact tests 13009K and 13009L at impact speed of 20 mph. ........................................................................................................ 118 Figure 80. Force vs. deflection plots from dynamic impact analysis with pre-defined properties in MAT143 for (a) clear wood, (b) grade DS-65 and (c) grade 1. ................................. 119

xi Figure 81. Energy vs. deflection plots from dynamic impact analysis with pre-defined properties in MAT143 for (a) clear wood, (b) grade DS-65 and (c) grade 1. ............................. 119 Figure 82. Sequential views of (a) Test 13009L and analyses for post model with pre-defined MAT143 properties for (b) clear wood, (c) grade DS-65 and (d) grade 1. ............... 120 Figure 83. Force vs. deflection plots from dynamic impact analysis using properties for (1) Grade 1 and (2) quality factors set to QT=0.60 and QC=0.7. ................................................ 121 Figure 84. Energy vs. deflection plots from dynamic impact analysis using properties for (1) Grade 1 and (2) quality factors set to QT=0.60 and QC=0.7....................................... 121 Figure 85. Soil springs attached directly to post. [Patzner99] ..................................................... 123 Figure 86. Soil modeled with non-linear springs and contact plates. .......................................... 124 Figure 87. Sequential views illustrating typical model response to simulated bogie impact load. .................................................................................................................................... 124 Figure 88. Force vs. displacement results from FE analysis compared with Test 13010F. ......... 125 Figure 89. Energy vs. displacement results from FE analysis compared with Test 13010F. ...... 125 Figure 90. Comparison of properties for the test and analysis vehicle. ....................................... 128 Figure 91. Comparison of G4(2W) guardrail after crash event for Test 471470-26 and FE analysis. ...................................................................................................................... 130 Figure 92. Sequential views of TTI Test 471470-26 and FE analysis from overhead viewpoint. .................................................................................................................................... 132 Figure 93. Sequential views of TTI Test 471470-26 and FE analysis from downstream viewpoint. .................................................................................................................................... 134 Figure 94. Sequential views of TTI Test 471470-26 and FE analysis from an oblique viewpoint behind the system. ...................................................................................................... 136 Figure 95. Location of accelerometer in FE model. ..................................................................... 139 Figure 96. Longitudinal acceleration-time history plot from accelerometer at c.g. for full-scale Test 471470-26 and FEA (10-ms and 50-ms moving averages)................................ 141 Figure 97. Lateral acceleration-time history plot from accelerometer at c.g. for full-scale Test 471470-26 and FEA (10-ms and 50-ms moving averages). ...................................... 141 Figure 98. Vertical acceleration-time history plot from accelerometer at c.g. for full-scale Test 471470-26 and FEA (10-ms and 50-ms moving averages). ...................................... 141 Figure 99. Yaw-time history plot from accelerometer at c.g. for full-scale test 471470-26 and FEA (angular rate and displacement). ................................................................................ 142 Figure 100. Roll-time history plot from accelerometer at c.g. for full-scale test 471470-26 and FEA (angular rate and displacement). ........................................................................ 142 Figure 101. Pitch-time history plot from accelerometer at c.g. for full-scale test 471470-26 and FEA (angular rate and displacement). ........................................................................ 142 Figure 102. Plot of global energy-time histories from the analysis. ............................................ 146

xii Figure 103. RSVVP metric selection for validation assessment. ................................................. 147 Figure 104. Posts from Ohio DOT procured for the Physical Test Program. .............................. 156 Figure 105. IML Resi-F400 S Resistograph. ............................................................................... 157 Figure 106. Schematic of typical (a) Free-body and (b) strain and stress diagrams for non- homogeneous beam under bending load. ................................................................... 158 Figure 107. Schematic illustrating internal force distribution through cross-section of a circular shaped post. ................................................................................................................ 159 Figure 108. Resistograph results for Post A. ................................................................................ 159 Figure 109. Schematic illustrating the local moduli and subareas associated with the various points through the post thickness at y = yi. ................................................................ 160 Figure 110. Cumulative distribution plot for M*. ......................................................................... 161 Figure 111. Cumulative distribution plot for U*. ......................................................................... 162 Figure 112. Resistograph data corrected for drift......................................................................... 162 Figure 113. Photo of post specimen soaking in tank of water. .................................................... 167 Figure 114. Rigid steel sleeve used for post mounting. ............................................................... 167 Figure 115. 2,372-lb pendulum device with semi-rigid nose. ...................................................... 168 Figure 116. Schematic of the accelerometer instrumentation for the pendulum tests. ................ 169 Figure 117. High-speed camera specifications and placement. ................................................... 170 Figure 118. Photo of Test 13009G1 showing Post 71 breaking below groundline. .................... 171 Figure 119. Typical force and energy curves annotated to illustrate location of peak force, initial rupture energy, and rupture energy computed from pendulum test results................ 172 Figure 120. Cumulative distribution plot for the peak force values measured in Test Series 13009 (Group 2). ................................................................................................................... 177 Figure 121. Cumulative distribution plot for the strain energy in the post at initiation of rupture measured in Test Series 13009 (Group 2). ................................................................. 177 Figure 122. Cumulative distribution plot for the total energy absorbed by the post at complete rupture measured in Test Series 13009 (Group 2). .................................................... 178 Figure 123. Peak Force vs. M* for Test Series 13009 Group 2 (all data). ................................... 178 Figure 124. Peak Moment vs. M* for Test Series 13009 Group 2 (all data). ............................... 179 Figure 125. Energy at rupture initiation vs. U* for Test Series 13009 Group 2 (all data). .......... 179 Figure 126. Rupture Energy vs. U* for Test Series 13009 group 2 (all data). ............................. 180 Figure 127. Test Summary Sheet for Test 13009Q1. ................................................................... 181 Figure 128. Test Summary Sheet for Test 13009S1. ................................................................... 182 Figure 129. Peak Force vs. M* for Test Series 13009 Group 2 (revised data set). ...................... 183 Figure 130. Energy at Initial Break vs. U* for Test Series 13009 Group 2 (revised data set). .... 183

xiii Figure 131. Test Summary Sheet for Test 13009T1. ................................................................... 184 Figure 132. Test summary sheet for Test 13009Y1. .................................................................... 185 Figure 133. Pendulum impact tests from Series 13009 corresponding to deterioration damage level 1 (DL1). ............................................................................................................. 188 Figure 134. Pendulum impact tests from Series 13009 corresponding to deterioration damage level 2 (DL2). ............................................................................................................. 188 Figure 135. Pendulum impact tests from Series 13009 corresponding to deterioration damage level 3 (DL3). ............................................................................................................. 188 Figure 136. Examples of aged posts corresponding to deterioration levels DL1 through DL3. .. 189 Figure 137. Graphical representation of damage levels with respect to resi-score, SM, and load capacity. ..................................................................................................................... 190 Figure 138. Graphical representation of damage levels with respect to resi-score, SU, and strain energy capacity........................................................................................................... 190 Figure 139. Tests 13010A, B and C resulted in relatively little soil displacement. ..................... 194 Figure 140. Force vs. deflection results for soil strength tests. .................................................... 195 Figure 141. Energy vs. deflection results for soil strength tests. ................................................. 195 Figure 142. Summary sheet for Test 13010G. ............................................................................ 197 Figure 143. Summary sheet for Test 13010H. ............................................................................. 198 Figure 144. Summary sheet for Test 13010I. ............................................................................... 199 Figure 145. Section modulus for round posts with radius ranging from 7 to 8 inches compared to the 6x8 rectangular post. ............................................................................................ 201 Figure 146. Finite element model used for calibrating material property values for various deterioration levels of wood posts. ............................................................................ 203 Figure 147. Force vs. deflection for DL1(a) wood post model corresponding to Test 13009H1 (ductile response). ...................................................................................................... 203 Figure 148. Energy vs. deflection for DL1(a) wood post model corresponding to Test 13009H1 (ductile response). ...................................................................................................... 204 Figure 149. Force vs. deflection for DL1(b) wood post model corresponding to Test 13009L1 (brittle response)......................................................................................................... 204 Figure 150. Energy vs. deflection for DL1(b) wood post model corresponding to Test 13009L1 (brittle response)......................................................................................................... 205 Figure 151. Sequential views of Test 13009H1 and FE analysis DL1(a). ................................... 206 Figure 152. Sequential views for Test 13009L1 and FE analysis DL1(b). .................................. 207 Figure 153. Force vs. deflection for DL1(a) wood post model corresponding to Test 13009H1 (ductile response). ...................................................................................................... 208

xiv Figure 154. Energy vs. deflection for DL1(a) wood post model corresponding to Test 13009H1 (ductile response). ...................................................................................................... 209 Figure 155. Force vs. deflection for DL3(a) wood post model and Tests 13009S1 and 13009N1 (more ductile response). ............................................................................................. 210 Figure 156. Force vs. deflection for DL3(b) wood post model and Tests 13009S1 and 13009N1 (more brittle response). .............................................................................................. 210 Figure 157. Energy vs. deflection for DL3(a) wood post model and Tests 13009S1 and 13009N1 (more ductile response). ............................................................................................. 211 Figure 158. Energy vs. deflection for DL3(b) wood post model and Tests 13009S1 and 13009N1 (more brittle response). .............................................................................................. 211 Figure 159. Analysis setup for evaluation of uniform deterioration of posts in the impact region. .................................................................................................................................... 213 Figure 160. Summary of barrier damage evaluation from analysis of uniform post deterioration. .................................................................................................................................... 214 Figure 161. Summary of anchor displacement at rail height from analysis of uniform post deterioration. .............................................................................................................. 215 Figure 162. Effective plastic strain contour plot for w-beam in splice connection at Post 16. .... 216 Figure 163. Summary of occupant impact velocity evaluation of uniform post deterioration. ... 218 Figure 164. Summary of maximum occupant ridedown acceleration evaluation of uniform post deterioration. .............................................................................................................. 218 Figure 165. Summary of 50-ms running average acceleration evaluation of uniform post deterioration. .............................................................................................................. 219 Figure 166. Summary of maximum effective plastic strains occurring at the splice-bolt locations at Post 16. ................................................................................................................... 219 Figure 167. Analysis setup for evaluation of mixed deterioration of posts in the impact region. 220 Figure 168. Summary of barrier damage evaluation from mixed post deterioration analyses. ... 221 Figure 169. Summary of anchor displacement at rail height from mixed post deterioration analyses. ..................................................................................................................... 222 Figure 170. Summary of occupant impact velocity evaluation of uniform post deterioration. ... 224 Figure 171. Summary of maximum occupant ridedown acceleration evaluation of uniform post deterioration. .............................................................................................................. 224 Figure 172. Summary of 50-ms running average acceleration evaluation of uniform post deterioration. .............................................................................................................. 225 Figure 173. Summary of maximum effective plastic strains occurring at the splice-bolt locations at Post 16. ................................................................................................................... 225 Figure 174. Sketch of typical guardrail anchor system. ............................................................... 230

xv Figure 175. Generic end-terminal used in full-scale crash test 2214-WB1 of a strong- post guardrail system.[Polivka06a] ............................................................................ 231 Figure 176. Example – finite element model for computing force-deflection response of the standard two-post guardrail anchor system.[Plaxico03] ............................................ 232 Figure 177. Test set-up for measuring force-deflection response of a standard two-post guardrail end-terminal anchor. .................................................................................................. 233 Figure 178. Photograph of anchor tubes with soil plates during installation. .............................. 234 Figure 179. Cable and pulley system used to apply tensile loading on end-terminal anchor. ..... 234 Figure 180. Video camera specifications and placement. ............................................................ 235 Figure 181. Displacement- and displacement rate-time histories measured at the load point on the end of the rail. ............................................................................................................ 236 Figure 182. Force-displacement response of the anchor system measured at the load point on the end of the rail. ............................................................................................................ 237 Figure 183. Displacement-time history at the end-of the rail and at the groundline of Post 2. ... 237 Figure 184. Sequential views of Test 13011B. ............................................................................ 238 Figure 185. Damage to end-terminal anchor in full-scale crash Test MGSDF-1.[Hascal07] ...... 239 Figure 186. Measured and approximated force-deflection response for the end-anchor. ............ 240 Figure 187. Analysis setup for evaluating effects of anchor strength on the performance of the G4(2W). ..................................................................................................................... 241 Figure 188. Summary of barrier damage evaluation from analyses of undamaged G4(2W) guardrail with various anchor strengths. .................................................................... 242 Figure 189. Summary of anchor displacement at rail height from analyses of undamaged G4(2W) guardrail with various anchor strengths. .................................................................... 243 Figure 190. Summary of occupant impact velocity (OIV) from analyses of undamaged G4(2W) guardrail with various anchor strengths. .................................................................... 244 Figure 191. Summary of occupant ridedown accelerations (ORA) from analyses of undamaged G4(2W) guardrail with various anchor strengths. ...................................................... 245 Figure 192. Summary of occupant risk measures from analyses of undamaged G4(2W) guardrail with various anchor strengths. ................................................................................... 245 Figure 193. Summary of maximum effective plastic strains occurring at the splice-bolt locations at Post 16. ................................................................................................................... 246 Figure 194. Summary of barrier damage evaluation from analyses of G4(2W) with combination of weak anchor and deteriorated posts. ...................................................................... 247 Figure 195. Summary of anchor displacement at rail height from analyses of G4(2W) with combination of weak anchor and deteriorated posts. ................................................. 248 Figure 196. Summary of occupant impact velocity (OIV) from analyses of G4(2W) with combination of weak anchor and deteriorated posts. ................................................. 249

xvi Figure 197. Summary of occupant ridedown accelerations (ORA) from analyses of G4(2W) with combination of weak anchor and deteriorated posts. ................................................. 250 Figure 198. Summary of occupant risk measures from analyses of G4(2W) with combination of weak anchor and deteriorated posts. .......................................................................... 250 Figure 199. Summary of maximum effective plastic strains occurring at the splice-bolt locations at Post 16. ................................................................................................................... 251 Figure 200. Snapshot from Test C08C3-2 illustrating torsion behavior of posts upstream of impact on the G4(1S).[Fleck08b]........................................................................................... 252 Figure 201. Snapshot from 471470-26 illustrating torsion behavior of posts upstream of impact on the G4(2W).[Mak99a] ................................................................................................ 252 Figure 202. System damage at upstream anchor resulting from Test MGSDF-1.[Hascall07] .... 253 Figure 203. Impact locations, IP01 and IP02, for low-speed impact cases. ................................. 256 Figure 204. Example of low-severity impact damage illustrating final position of post-bolts relative to the slotted hole in w-beam. ....................................................................... 258 Figure 205. Extent of damage resulting from impact on G4(2W) at 30 mph at Impact Point. .... 259 Figure 206. Initial conditions used in evaluating effects of low-level guardrail deflection on the performance of the G4(2W). ...................................................................................... 260 Figure 207. Summary of barrier damage resulting from analysis of high-speed impact into the G4(2W) with pre-existing low-severity rail deflection. ............................................. 262 Figure 208. Summary of anchor displacement at rail height from analysis of high-speed impact into the G4(2W) with pre-existing low-severity rail deflection. ................................ 262 Figure 209. Summary of maximum effective plastic strains occurring at splice-bolt locations. . 263 Figure 210. Summary of occupant impact velocity (OIV) from analysis of high-speed impact into the G4(2W) with pre-existing low-severity rail deflection. ....................................... 265 Figure 211. Summary of occupant ridedown accelerations (ORA) from analysis of high-speed impact into the G4(2W) with pre-existing low-severity rail deflection. .................... 265 Figure 212. Summary of 50-ms average acceleration from analysis of high-speed impact into the G4(2W) with pre-existing low-severity rail deflection. ............................................. 266 Figure 213. Results of Test MGA C08C3-027.2 illustrating torsional deformation of the W6x8 steel guardrail posts during vehicle collision.[Fleck08b] .......................................... 268 Figure 214. Results of Test 471470-26 illustrating the response of the wooden guardrail posts during vehicle collision.[Mak99] ............................................................................... 268 Figure 215. Results of Test 404201-1 illustrating brittle fracture of wood posts due to tensile forces in the w-beam rail.[Bullard00] ........................................................................ 269 Figure 216. Anchor used in evaluation of the modified G4(1S) with wood blockouts in tests (a) 405421-1 [Bullard96], (b) 2214-WB2 [Polivka06b] and (c) C08C3-027 [Fleck08a;08b]. .......................................................................................................... 271 Figure 217. Damage to guardrail in low-speed impact test C08C3-027-1.[Fleck08a] ................ 272

xvii Figure 218. Damage to guardrail in low-speed test C08C3-027-1 (overhead view).[Fleck08a] 273 Figure 219. Finite element model of G4(1S) for simulation of Test C08C3-027-1. .................... 274 Figure 220. Sequential views of FEA results compared with Test C08C3-027-1. ...................... 276 Figure 221. Impact response at 0.18 seconds for (a) full-scale test and (b) FEA illustrating wheel orientation. ................................................................................................................. 277 Figure 222. Comparison of guardrail damage for (a) Test C08C3-027-1 and (b) FEA model. ... 278 Figure 223. Photo of upstream anchor after Test C08C3-027-1.[Fleck08a] ............................... 278 Figure 224. Contours of effective plastic strain for the initial state of the guardrail model for simulation of Test C08C3-027-2. ............................................................................... 280 Figure 225. Sequential Views of Test C08C3-027-2 and FE analysis Case 1 from downstream- backside view perspective. ......................................................................................... 282 Figure 226. Sequential Views of Test C08C3-027-2 and FE analysis Case 1 from an upstream view perspective. ........................................................................................................ 284 Figure 227. Vehicle impacts against Post 15 in analysis Case 1. ................................................. 286 Figure 228. Longitudinal acceleration-time history at C.G. of pickup truck model in local coordinates for analysis Case 1. ................................................................................. 286 Figure 229. Lateral acceleration-time history at C.G. of pickup truck model in local coordinates for analysis Case 1. .................................................................................................... 287 Figure 230. Vertical acceleration-time history at C.G. of pickup truck model in local coordinates for analysis Case 1. .................................................................................................... 287 Figure 231. Acceleration-time history at C.G. of pickup truck model in local coordinates for analysis Case 1. .......................................................................................................... 287 Figure 232. Summary report of occupant risk measures for the analysis Case 1. ........................ 288 Figure 233. Test setup for low-speed test C08C3-027-1 illustrating the limited distance to the back-edge of the soil-pit for the test article. ............................................................... 289 Figure 234. Snapshots from low-speed test C08C3-027-1 illustrating the position of the guardrail posts relative to the backside of the soil pit at the beginning of the test and at 0.16 seconds. ...................................................................................................................... 290 Figure 235. Test setup for high-speed test C08C3-027-2 illustrating the reduced distance from the back of Posts 11 and 12 to the back-edge of the soil-pit. ........................................... 290 Figure 236. FE model for Case 2 with vertical “rigidwall” located just below grade to simulate back-edge of soil pit (overhead viewpoint). ............................................................... 291 Figure 237. FE model for Case 2 with vertical “rigidwall” located just below grade to simulate back-edge of soil pit (downstream viewpoint). .......................................................... 291 Figure 238. Sequential Views of Test C08C3-027-2 and FE analysis from downstream-backside view perspective. ........................................................................................................ 293

xviii Figure 239. Sequential views of Test C08C3-027-2 and FE analysis from an upstream view perspective.................................................................................................................. 295 Figure 240. Permanent displacement of the upstream anchor in Test C08C3-027-2. ................. 298 Figure 241. Displacement of upstream rail boundary in FEA analysis Case 2 (modeled with 47% baseline anchor stiffness). .......................................................................................... 298 Figure 242. Maximum rotation displacement of Post 10 in (a) full-scale test and (b) FEA analysis Case 2. ........................................................................................................................ 299 Figure 243. Anchor stiffness used in FEA model compared to anchor stiffness measured in physical tests. ............................................................................................................. 301 Figure 244. Example of soil erosion at a guardrail post. .............................................................. 303 Figure 245. Example of severe soil erosion at multiple posts. ..................................................... 304 Figure 246. Test set-up for pendulum tests. ................................................................................. 305 Figure 247. 2,372-lb pendulum device with semi-rigid nose. ...................................................... 307 Figure 248. Schematic of the accelerometer instrumentation for the pendulum tests. ................ 307 Figure 249. High-speed camera specifications and placement. ................................................... 308 Figure 250. Repair to the pendulum head included adding a steel “slide Plate” underneath the head. ........................................................................................................................... 310 Figure 251. Force vs. deflection curves for Test Series 14003 from primary accelerometer. ..... 312 Figure 252. Force vs. deflection curves for Test Series 14003 from secondary accelerometer. .. 312 Figure 253. Energy vs. deflection curves for Test Series 14003 from primary accelerometer. ... 313 Figure 254. Energy vs. deflection curves for Test Series 14003 from secondary accelerometer. 313 Figure 255. Peak “impulse” force in Test Series 14003............................................................... 314 Figure 256. Total energy vs. erosion for Test Series 14003 – energy values correspond to point when pendulum overrides the post. ............................................................................ 314 Figure 257. Total energy vs. erosion for Test Series 14003 – average of primary and secondary accelerometers – including linear curve fit to the data. ............................................. 315 Figure 258. Finite element model used for validating/calibrating soil-spring stiffness corresponding to various levels of soil erosion. ......................................................... 316 Figure 259. Force vs. deflection for DL0 soil model compared to Tests 14003B and 14003F. .. 317 Figure 260. Energy vs. deflection for DL0 soil model compared to Tests 14003B and 14003F. 317 Figure 261. Sequential views of Test 14003F and FE analysis on baseline post-soil case, DL0. 318 Figure 262. Force vs. deflection for soil model with 3” erosion compared to Test 14003A. ...... 319 Figure 263. Energy vs. deflection for soil model with 3” erosion compared to Test 14003A. .... 319 Figure 264. Sequential views of Test 14003A and FE analysis for 3-inch erosion case. ............ 320 Figure 265. Force vs. deflection for soil model with 6” erosion compared to Test 14003C. ...... 321

xix Figure 266. Energy vs. deflection for soil model with 6” erosion compared to Test 14003C. .... 321 Figure 267. Sequential views of Test 14003C and FE analysis for 6-inch erosion case. ............ 322 Figure 268. Force vs. deflection for soil model with 9” erosion compared to Test 14003D. ...... 323 Figure 269. Energy vs. deflection for soil model with 9” erosion compared to Test 14003D. .... 323 Figure 270. Sequential views of Test 14003D and FE analysis for 9-inch erosion case. ............ 324 Figure 271. Force vs. deflection for soil model with 12” erosion compared to Test 14003E. .... 325 Figure 272. Energy vs. deflection for soil model with 12” erosion compared to Test 14003E. .. 325 Figure 273. Sequential views of Test 14003E and FE analysis for 12-inch erosion case. ........... 326 Figure 274. Analysis setup for evaluating effects of anchor strength on the performance of the G4(2W). ..................................................................................................................... 327 Figure 275. Summary of barrier damage evaluation from analyses of undamaged G4(2W) guardrail with various levels of soil erosion at a single post. .................................... 328 Figure 276. Summary of anchor displacement at rail height from analyses of undamaged G4(2W) guardrail with various levels of soil erosion at a single post. .................................... 329 Figure 277. Summary of occupant impact velocities for undamaged G4(2W) guardrail with various levels of soil erosion at a single post. ............................................................ 330 Figure 278. Summary of maximum occupant ridedown accelerations for undamaged G4(2W) guardrail with various levels of soil erosion at a single post. .................................... 331 Figure 279. Summary of maximum 50-ms running average accelerations for undamaged G4(2W) guardrail with various levels of soil erosion at a single post. .................................... 331 Figure 280. Summary of maximum effective plastic strains occurring at the splice-bolt locations at Post 16. ................................................................................................................... 332 Figure 281. Summary of barrier damage evaluation from analyses of undamaged G4(2W) guardrail with various levels of soil erosion at two consecutive posts. ..................... 333 Figure 282. Summary of anchor displacement at rail height from analyses of undamaged G4(2W) guardrail with various levels of soil erosion at two consecutive posts. ..................... 334 Figure 283. Summary of occupant impact velocities for undamaged G4(2W) guardrail with various levels of soil erosion at two consecutive posts. ............................................. 335 Figure 284. Summary of maximum occupant ridedown accelerations for undamaged G4(2W) guardrail with various levels of soil erosion at two consecutive posts. ..................... 336 Figure 285. Summary of maximum 50-ms running average accelerations for undamaged G4(2W) guardrail with various levels of soil erosion at two consecutive posts. ..................... 336 Figure 286. Summary of maximum effective plastic strains occurring at the splice-bolt locations at Post 16. ................................................................................................................... 337 Figure 287. Example – finite element model for computing force-deflection response of the standard two-post guardrail anchor system.[Plaxico03] ............................................ 341

xx Figure 288. Typical test set-up for measuring force-deflection response of the guardrail end- terminal anchor........................................................................................................... 344 Figure 289. Photograph of anchor tubes with soil plates during installation (from preliminary Test 14011B). ..................................................................................................................... 344 Figure 290. Photo of the simulated terminal-head bracket mounted onto the end-post. .............. 345 Figure 291. Cable and pulley system used to apply tensile loading on end-terminal anchor. ..... 345 Figure 292. Idler-pulley mount used to maintain vertical position of loading cable. .................. 346 Figure 293. Comparison of the two post types used in the end-terminal tests. ............................ 346 Figure 294. Displacement transducers mounted to (a) w-beam rail at load point and (b) top of foundation tube at Post 1. ........................................................................................... 347 Figure 295. Video camera specifications and placement. ............................................................ 348 Figure 296. Displacement- and displacement rate-time histories measured at the load point on the end of the rail and at the groundline of Post 1 for baseline case. ............................... 349 Figure 297. Force-displacement response of the anchor system measured at the load point on the end of the rail for undamaged end-terminal case. ...................................................... 350 Figure 298. Sequential views of quasi-static test conducted for undamaged end-terminal case (Test 14011E). ............................................................................................................ 351 Figure 299. Pre-test photo of Test 14001D (front view). ............................................................. 354 Figure 300. Post-test photo of Test 14001D (back view). ........................................................... 355 Figure 301. Force vs. deflection response for the standard end-terminal with missing groundline strut. ............................................................................................................................ 355 Figure 302. Displacement and displacement rate vs. time for Test 14001D. .............................. 356 Figure 303. Typical position of groundline strut in a standard two-post-strut anchor system relative to (a) Post 2 and (b) Post 1. ........................................................................... 356 Figure 304. Procedure for measuring reduced embedment depth. ............................................... 357 Figure 305. Pre-test photo of Test 14001M for 2-inch reduced embedment case. ...................... 358 Figure 306. Pre-test photo of Test 14001F for 4-inch reduced embedment case. ........................ 359 Figure 307. Pre-test photo of Test 14001L for 6-inch reduced embedment case. ....................... 359 Figure 308. Pre-test photo of Test 14001G for 8-inch reduced embedment case. ....................... 360 Figure 309. Post-test photo of Test 14001M for 2-inch reduced embedment case. ..................... 360 Figure 310. Post-test photo of Test 14001F for 4-inch reduced embedment case. ...................... 361 Figure 311. Post-test photo of Test 14001L for 6-inch reduced embedment case. ...................... 361 Figure 312. Post-test photo of Test 14001G for 8-inch reduced embedment case. ..................... 362 Figure 313. Force vs. deflection response for the standard end-terminal with 0 to 8 inches reduced embedment depth of foundation tubes. ...................................................................... 362

xxi Figure 314. Illustration showing procedure for measuring slack in cable-anchor. ...................... 363 Figure 315. Pre-test photo of Test 14001H for 1” slack-cable case. ............................................ 364 Figure 316. Pre-test photo of Test 14001I for 2” slack-cable case. ............................................. 364 Figure 317. Pre-test photo of Test 14001K for 3” slack-cable case. ............................................ 365 Figure 318. Pre-test photo of Test 4001J for 4” slack-cable case. ............................................... 365 Figure 319. Post-test photos of Test 14001H for 1” slack-cable case. ......................................... 366 Figure 320. Post-test photos of Test 14001I for 2” slack-cable case. .......................................... 366 Figure 321. Post-test photos of Test 14001K for 3” slack-cable case. ......................................... 366 Figure 322. Post-test photos of Test 14001J for 4” slack-cable case. .......................................... 367 Figure 323. Force vs. deflection response for the standard end-terminal with 0 to 4 inches of slack in the anchor-cable. .................................................................................................... 367 Figure 324. Test 14001H showing continuing effectiveness of anchor after Post 2 fails. ........... 369 Figure 325. Rail flattening – Rail flattening and rail crush at each quadrant of the splice is measured from the center of the w-beam to the top/bottom edge at the splice bolts. 378 Figure 326. Rail separation - Lateral gap between rail elements at splice connection (measurements taken at locations adjacent to the eight splice bolts). ........................ 378 Figure 327. Rail separation – Longitudinal slip in splice connection. ......................................... 379 Figure 328. Gouging – Gouging of splice-bolts into w-beam panel is evidenced by rotation of the bolt about the vertical axis. ........................................................................................ 379 Figure 329. Splice bolt hole stretching – Stretching of the splice bolt hole is evidenced in this photo by the apparent longitudinal movement of the splice bolt relative to its original position. ...................................................................................................................... 380 Figure 330. Horizontal tear in post bolt hole – This photo shows evidence of both stretching and a horizontal tear in the post bolt hole. ........................................................................... 380 Figure 331. Horizontal and vertical tears – tears were measured and categorized according to location on upstream and downstream panel as denoted here. .................................. 381 Figure 332. 4,360-lb pendulum device with semi-rigid nose. ...................................................... 387 Figure 333. Schematic of the accelerometer instrumentation for the pendulum tests. ................ 388 Figure 334. High-speed camera specifications and placement. ................................................... 389 Figure 335. Sequential views of a pendulum test performed in Gabler’s study. ......................... 390 Figure 336. Pocketing during full-scale crash test C08C3-27.2.[Fleck08b] ................................ 390 Figure 337. Test set-up for Test Series 14004. ............................................................................ 391 Figure 338. Anchoring of the downstream end of the rail for Test Series 14004. ....................... 392 Figure 339. Anchoring of the upstream end of the rail for Test Series 14004. ........................... 392

xxii Figure 340. Typical mounting position for post-bolt was on the downstream side of the slotted hole on the rail. ........................................................................................................... 392 Figure 341. Peak impact force for each damage mode case investigated in test series 14004F-O. .................................................................................................................................... 396 Figure 342. Peak impact energy for each damage mode case investigated in test series 14004F-O. .................................................................................................................................... 396 Figure 343. (a) Force vs. Deflection and (b) Energy vs. Deflection curves for damaged splices with flattened cross-section compared to undamaged cases. ..................................... 397 Figure 344. (a) Force vs. Deflection and (b) Energy vs. Deflection curves for damaged splices with longitudinal slip compared to undamaged cases. ............................................... 398 Figure 345. (a) Force vs. Deflection and (b) Energy vs. Deflection curves for damaged splice with vertical crush compared to undamaged cases. ........................................................... 399 Figure 346. (a) Force vs. Deflection and (b) Energy vs. Deflection curves for damaged splice with combination of lateral rail separation and flattened rail compared to undamaged cases. .................................................................................................................................... 400 Figure 347. Sequential views of Tests 14004F and 14004G. ....................................................... 401 Figure 348. Sequential views of Tests 14004H and 14004I......................................................... 402 Figure 349. Sequential views of Tests 14004J and 14004K. ....................................................... 403 Figure 350. Sequential views of Tests 14004L and 14004M. ...................................................... 404 Figure 351. Sequential views of Tests 14004N and 14004O. ...................................................... 405 Figure 352. Overhead view of Test 14004K from high-speed video camera. ............................. 406 Figure 353. Results of Test 14004F with rail tear passing through all four downstream splice-bolt holes. .......................................................................................................................... 407 Figure 354. Flow chart for the online guide’s guardrail assessment. ........................................... 413 Figure 355. Photos of the crash site for Example 1. .................................................................... 418 Figure 356. Photos of the crash site for Example 2. .................................................................... 425 Figure 357. Photos of the crash site for Example 3. .................................................................... 433 LIST OF TABLES Table 1. Methods for evaluating damage modes in NCHRP Report 656. [Gabler10] .................. 3 Table 2. NCHRP Report 350 and MASH TL-3 for Guardrail. ....................................................... 7 Table 3. Summary of guardrail systems that have been full-scale crash tested under TL-3 conditions. .................................................................................................................. 25 Table 4. Summary of full-scale test results on guardrail systems tested under TL-3 conditions. 26 Table 5. Pendulum tests on wood and steel posts. [Bronstad88; Hascall07] .............................. 34

xxiii Table 6. TL-2 computer simulation results. [Marzougui10]........................................................ 40 Table 7. Full-Scale crash test impact conditions and results. [Rosson96] ................................... 41 Table 8. Test matrix for post-in-soil bogie tests. [Rosson96] ...................................................... 41 Table 9. BARRIER VII post input variables. [Rosson96] ........................................................... 42 Table 10. BARRIER VII maximum dynamic deflection results. [Rosson96] ............................. 44 Table 11. Steel post bogie impact test matrix. [Polivka00b] ....................................................... 44 Table 12. Steel post bogie test results. [Polivka00b] ................................................................... 45 Table 13. BARRIER VII computer simulation results. [Polivka00b] ......................................... 45 Table 14. Comparison of full-scale test results for MGS with 12-inch blockouts, 8-inch blockouts and no blockouts.[Rosenbaugh12] ............................................................ 50 Table 15. Summary of pendulum test and model results. [Hampton10] ..................................... 54 Table 16. Summary of generic end terminal repair guidance. [Gabler10] .................................. 67 Table 17. Summary of common strong and weak post guardrail systems. .................................. 74 Table 18. Summary of possible methods for assessing damage modes for the G4(1W) and G4(2W) guardrail systems. ........................................................................................ 86 Table 19. Summary of possible methods for assessing damage modes for thrie-beam guardrail systems. ...................................................................................................................... 90 Table 20. Summary of possible methods for assessing damage modes for the modified thrie- beam guardrail system. .............................................................................................. 92 Table 21. Summary of possible methods for assessing damage modes for the MGS with steel posts. .......................................................................................................................... 93 Table 22. Summary of possible methods for assessing damage modes for MGS with wood posts. ................................................................................................................................... 94 Table 23. Summary of possible methods for assessing damage modes for the Modified G2 guardrail. .................................................................................................................... 96 Table 24. Summary of generic end terminal repair guidance. [Gabler10] .................................. 98 Table 25. Summary of possible methods for assessing damage modes for generic end terminals. ................................................................................................................................... 98 Table 26. Guardrail damage modes. .......................................................................................... 100 Table 27. Prioritization of damage modes. ................................................................................ 103 Table 28. Predefined material parameters values for *MAT_WOOD_PINE in LS-DYNA for various quality factor settings (units: Mg, mm, sec, N, MPa). ................................ 116 Table 29. Groundline deflections of posts for Test 471470-26 and FE analysis. ...................... 130 Table 30. Summary of phenomenological events of full-scale test 471470-26 and FEA simulation. ............................................................................................................... 138

xxiv Table 31. Summary of occupant risk measures computed from Test 471470-26 and FEA simulation. ............................................................................................................... 140 Table 32. Analysis solution verification table. .......................................................................... 146 Table 33. Roadside safety validation metrics rating table – time history comparison (single- channel option). ....................................................................................................... 149 Table 34. Roadside safety validation metrics rating table – (multi-channel option). ................ 150 Table 35. Report 350 crash test criteria with the applicable test numbers. ............................... 151 Table 36. Roadside safety phenomena importance ranking table (structural adequacy). .......... 152 Table 37. Roadside safety phenomena importance ranking table (occupant risk). ................... 153 Table 38. Roadside safety phenomena importance ranking table (vehicle trajectory). ............. 154 Table 39. Test Series 13009 Group 1 (2,372-lb pendulum, velocity = 20 mph, impact point = 21.5 inches). ............................................................................................................. 164 Table 40. Test Series 13009 Group 2 (2,372-lb pendulum, velocity = 10 mph, impact point = 21.5 inches). ............................................................................................................. 165 Table 41. Test Results for Test Series 13009 Group 1 (2,372-lb pendulum, velocity = 20 mph, impact point = 21.5 inches). .................................................................................... 173 Table 42. Test Results for Test Series 13009 Group 2 (2,372-lb pendulum, velocity = 10 mph, impact point = 21.5 inches). .................................................................................... 175 Table 43. Statistics for Post Strength Capacity from Pendulum Test Series 13009 (Group 2). 177 Table 44. Deterioration damage levels for posts in Test 13009 Series 2 based on strain energy. ................................................................................................................................. 187 Table 45. Damage levels for guardrail post deterioration. ......................................................... 189 Table 46. Post-in-Soil Test Group 1 (2,372-lb pendulum, v = 20 mph, impact point = 24.88 inches, embedment 40 inches). ................................................................................ 193 Table 47. Post-in-Soil Test Group 2 (2,372-lb pendulum, v = 20 mph, impact point = 21.5 inches, embedment 40 inches). ................................................................................ 193 Table 48. Material properties for wood post model corresponding to damage levels 1 through 3. ................................................................................................................................. 202 Table 49. Analysis matrix for deteriorated wood post study. .................................................... 212 Table 50. Summary of barrier damage evaluation from uniform post deterioration analyses. . 213 Table 51. Summary of occupant risk measures from evaluation of uniform post deterioration analyses. ................................................................................................................... 217 Table 52. Summary of barrier damage evaluation from mixed post deterioration analyses. .... 221 Table 53. Summary of occupant risk measures from mixed post deterioration analyses. ......... 223 Table 54. Recommendations for wood post deterioration damage. ........................................... 229 Table 55. Analysis matrix for Task 4A-2. ................................................................................. 232

xxv Table 56. Summary of barrier damage evaluation from analyses of undamaged G4(2W) guardrail with various anchor strengths. .................................................................. 242 Table 57. Summary of occupant risk measures from analyses of undamaged G4(2W) guardrail with various anchor strengths. ................................................................................. 244 Table 58. Summary of barrier damage evaluation from analyses of G4(2W) with combination of weak anchor and deteriorated posts. ........................................................................ 247 Table 59. Summary of occupant risk measures from analyses of G4(2W) with combination of weak anchor and deteriorated posts. ........................................................................ 249 Table 60. Recommendations for end-terminal damage for the G4(2W). .................................. 254 Table 61. Simulation matrix for creating low-severity guardrail deflection damage cases....... 256 Table 62. Summary of results for the low-severity impact analyses. ........................................ 257 Table 63. Summary of barrier damage resulting from analysis of high-speed impact into the G4(2W) with pre-existing low-severity rail deflection. .......................................... 261 Table 64. Summary of occupant risk measures from analysis of high-speed impact into the G4(2W) with pre-existing low-severity rail deflection. .......................................... 264 Table 65. Recommendations for post and rail deflection damage. ............................................ 270 Table 66. Summary of phenomenological events of full-scale test C08C3-027-2 and FEA simulation. ............................................................................................................... 297 Table 67. Dry density of soil for each test case measured at 6-inch lifts. ................................. 306 Table 68. Pendulum test matrix for erosion study showing post embedment, soil properties and impact conditions. .................................................................................................... 306 Table 69. Summary of results for Test Series 14003. ................................................................ 311 Table 70. Simulation matrix for evaluating soil erosion around creating low-severity guardrail deflection damage cases. ......................................................................................... 326 Table 71. Summary of barrier damage evaluation from analyses of undamaged G4(2W) guardrail with various levels of soil erosion at a single post. .................................. 328 Table 72. Summary of occupant risk measures from evaluation of undamaged G4(2W) guardrail with various levels of soil erosion at a single post. ................................................. 330 Table 73. Summary of barrier damage evaluation from analyses of undamaged G4(2W) guardrail with various levels of soil erosion at two consecutive posts. ................... 333 Table 74. Summary of occupant risk measures from evaluation of undamaged G4(2W) guardrail with various levels of soil erosion at two consecutive posts. .................................. 335 Table 75. Recommendations for soil erosion around guardrail posts for the G4(2W). ............. 339 Table 76. Summary of generic end terminal repair guidance. [Gabler10] ................................ 340 Table 77. Test matrix for the anchor system damage study. ..................................................... 343 Table 78. Quasi-static test results for end-terminal damage modes (Table 1 of 2). .................. 352

xxvi Table 79. Quasi-static test results for end-terminal damage modes (Table 2 of 2). .................. 353 Table 80. Recommendations for end-terminal damage for the G4(2W). .................................. 373 Table 81. Summary of “rail flattening” damage mode for MEDOT crash-damaged splice specimens – listed in descending order, w.r.t maximum degree of flattening. ........ 382 Table 82. Summary of “rail crush” damage mode for MEDOT crash-damaged splice specimens – listed in descending order, w.r.t maximum degree of crush. ................................ 383 Table 83. Summary of “rail separation” damage mode for MEDOT crash-damaged splice specimens – listed in descending order, w.r.t maximum separation. ...................... 384 Table 84. Summary of “visible splice bolt and splice bolt hole” damage mode for MEDOT crash-damaged splice specimens. ............................................................................ 385 Table 85. Summary of “non-bolt-hole tear” damage mode for MEDOT crash-damaged splice specimens – listed in descending order w.r.t maximum vertical tear, then maximum horizontal tear. ......................................................................................................... 386 Table 86. Pendulum test matrix for the splice damage study. ................................................... 394 Table 87. Results of pendulum test series 14004. ...................................................................... 395 Table 88. Recommendations for assessment criteria for w-beam splice damage. ..................... 410 LIST OF APPENDICES Appendix A: A Guide for W-Beam Guardrail Damage Assessment – A Field Manual for Highway Maintenance Personnel Appendix B: Survey of Practice Appendix C: Validation/Verification Report Forms Appendix D: Assess Effects of Guardrail Post Deterioration on Performance of G4(2W) – FOIL Tests 13009 B-W Summary Sheets (Posts in Rigid Foundation) Appendix E: Assess Effects of Guardrail Post Deterioration on Performance of G4(2W) – FOIL Tests 13009 Y-K2 Summary Sheets (Posts in Rigid Foundation) Appendix F: Assess Effects of Guardrail Post Deterioration on Performance of G4(2W) – FOIL Tests 13010 Summary Sheets (Posts in Soil) Appendix G: Sequential Views from FEA Evaluation of Uniform Post Deterioration in Impact Region Appendix H: Sequential Views from FEA Evaluation of Deteriorated Posts Located Upstream of Undamaged Posts Appendix I: Sequential Views from FEA Evaluation of G4(2W) with Various Anchor Strengths Appendix J: Sequential Views from FEA Evaluation of G4(2W) with Combination of Weak Anchor and Deteriorated Posts

xxvii Appendix K: Sequential Views from FEA Evaluation of G4(2W) Under Low-Speed Impact (To Induce Low-Severity Rail Deflection) Appendix L: Sequential Views from FEA Evaluation of High-Speed Impact into G4(2W) with Low-Severity Rail Deflections Appendix M: Assess Effects of Soil Eroded Away from Posts on Performance of G4(2W) – FOIL Tests 14003 Summary Sheets (Pendulum Tests on Posts in Soil) Appendix N: Sequential Views from FEA Evaluation of G4(2W) with Various Levels of Erosion at a Single Post Appendix O: Sequential Views from FEA Evaluation of G4(2W) with Various Levels of Erosion at Two Consecutive Posts Appendix P: Construction Drawings for the Baseline Generic End-Terminal Appendix Q: Quantify Anchor Strength in Terms of Anchor Damage Modes Appendix R: Visual Inspection of Crash-Damaged Splice Specimens – Damage Summary Sheets Appendix S: Quantify Effects of W-Beam Splice Damage on Capacity of Railing – FOIL Tests 14004 Summary Sheets (Pendulum Impact Study) Note: The appendices listed here can be found on the TRB website (www.trb.org) by searching for NCHRP Web-Only Document 304: Criteria for Restoration of Longitudinal Barriers, Phase II.

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Guardrails are an important feature of the roadside that are used to shield errant motorists from becoming involved in even more catastrophic crashes by redirecting vehicles away from fixed hazards such as trees and poles and terrain hazards such as steep roadside slopes and fill embankments.

The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 304: Criteria for Restoration of Longitudinal Barriers, Phase II develops a Field Guide to assist maintenance personnel in making decisions about repairing damaged guardrail installations.

Supplementary material to the document is Appendices A-S.

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