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NCHRP Web-Only Document 307 Guidelines for the Selection of Test Levels 2 through 5 Bridge Railings Malcolm H. Ray Christine E. Carrigan RoadSafe LLC Canton, ME Contractorâs Final Report for NCHRP Project 22-12(03) Submitted March 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 techniquesâthe 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 Boardâs 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 307 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs David Jared, Senior Program Officer Clara Schmetter, Program Associate Natalie Barnes, Director of Publications Heather DiAngelis, Associate Director of Publications Jennifer Correro, Assistant Editor NCHRP PROJECT 22-12(03) PANEL Field of DesignâArea of Vehicle Barrier Systems Don Jay Gripne, DJG NW INC, Olympia, WA (Chair) Alexander K. Bardow, Massachusetts Department of Transportation, Boston, MA Brian L. Bowman, Auburn University, Auburn, AL Owen S. Denman, Owen S. Denman, PE Consulting, Pismo Beach, CA Paul Fossier, Consultant, Baton Rouge, Louisiana Rodney D. Lacy, Overland Park, KS Charles F. McDevitt, McDevitt Consulting, Matthews, NC Aurora Meza, VRX, Inc., Austin, TX Jiten Soneji, Delaware Department of Transportation, Dover, DE Harry W. Taylor, Jr., Taylor Consulting, Washington, DC Richard Albin, FHWA Liaison Stephen F. Maher, TRB Liaison
iv TABLE OF CONTENTS Introduction ....................................................................................................................... 1 Literature Review ............................................................................................................. 3 Exemplar Crashes ........................................................................................................... 4 Crashes in the Media ................................................................................................... 4 Crashes Investigated by the National Transportation Safety Board ......................... 12 Crash Testing ................................................................................................................ 20 NCHRP Report 230 .................................................................................................. 20 1989 AASHTO Guide Specification for Bridge Railings ......................................... 21 NCHRP Report 350 .................................................................................................. 22 Manual for Assessing Safety Hardware (MASH) .................................................... 24 High-Containment Barriers ....................................................................................... 25 Guidelines and Specifications ....................................................................................... 28 FHWA and AASHTO ............................................................................................... 28 The States .................................................................................................................. 36 International Specifications ...................................................................................... 44 Summary ................................................................................................................... 54 Crash Data Studies ........................................................................................................ 57 FHWA Narrow Bridge Study ................................................................................... 57 NCHRP 22-08 ........................................................................................................... 58 Kansas Bridge Rail Study ......................................................................................... 60 Analysis Methods for Bridge Railing Selection ........................................................... 61 BCAP ........................................................................................................................ 61 RSAP......................................................................................................................... 65 RRRAP ..................................................................................................................... 67 Risk Analysis ............................................................................................................ 68 Conclusions ................................................................................................................... 68 Results Of Survey Of Practice ....................................................................................... 71 Introduction ................................................................................................................... 71 Survey Questions .......................................................................................................... 71 Summary ....................................................................................................................... 81
v Development of Bridge Rail Selection Guidelines........................................................ 82 Crash Data ..................................................................................................................... 82 New Jersey Median Barrier ...................................................................................... 83 Massachusetts Median Barrier .................................................................................. 84 Washington State Median Barrier ............................................................................. 86 Pennsylvania Bridge Railing..................................................................................... 87 Ohio Bridge Railing .................................................................................................. 89 Nebraska Bridge Rails .............................................................................................. 92 After Penetration Hazards ......................................................................................... 94 Summary of Crash Data ............................................................................................ 95 Encroachment ............................................................................................................... 95 Encroachment Models for Roads Over Capacity ..................................................... 96 Low-Volume Encroachments ................................................................................... 96 Annual Traffic Growth ............................................................................................. 97 Traffic Mix Considerations ....................................................................................... 97 Truck Trajectories ................................................................................................... 101 Encroachment Adjustments for Site-Specific Characteristics ................................ 112 Crash ........................................................................................................................... 114 Predicted Penetration, Rollovers and Vaults .......................................................... 114 Severity ....................................................................................................................... 119 Bridge Railing Crash Severity ................................................................................ 119 Bridge Railing Penetration Severity ....................................................................... 121 Costs ............................................................................................................................ 123 Project Life.............................................................................................................. 123 Regional Cost Variations ........................................................................................ 124 Temporal Cost Variations ....................................................................................... 129 Bridge Railing Agency Costs.................................................................................. 132 Bridge Railing Crash Costs ..................................................................................... 133 Sight Distance Considerations .................................................................................... 137 Analysis Methods ....................................................................................................... 140 Benefit-Cost versus Risk Approach ........................................................................ 141
vi Developing the Selection Guidelines ...................................................................... 142 Selection Guidelines ...................................................................................................... 150 Bridge Rail Risk Assessment Process ........................................................................ 150 Discussion ................................................................................................................... 159 Implementation ....................................................................................................... 159 Critical Values for Design ...................................................................................... 160 Test Levels Considerations ..................................................................................... 161 The Risk Line .......................................................................................................... 162 Recommended Selection Guidelines Verification ...................................................... 164 Comparisons to the 1989 AASHTO Guide Specification and NCHRP 22-08 ....... 164 Example Bridge Railing Selection .......................................................................... 165 Conclusions .................................................................................................................... 173 Appendix A: Alternative Graphs for Figure 32 ......................................................... 175 Appendix B: Bridge Rail Selection Guidelines ........................................................... 184 Bridge Rail Risk Assessment Process ........................................................................ 185 References ...................................................................................................................... 194
vii LIST OF TABLES Table 1. Crash Test Acceptance Equivalencies from the FHWA. [Horne97] ............................................................. 23 Table 2. Approximate Crash Test Acceptance Equivalencies. [after Horne97] .......................................................... 25 Table 3. Summary of test information for selected heavy tractor-trailer crash tests. ................................................... 27 Table 4. 60 mi/hr portion of the 1989 GSRB selection table.[AASHTO89] ............................................................... 30 Table 5. Bridge railing capacity recommendations in BCAP and NCHRP 22-08.[after Mak94] ................................ 32 Table 6. Revised selection guidelines for bridge railings based on NCHRP 22-08. [Mak94] ..................................... 34 Table 7 Summary of Minnesota âTABLE 13.2.1: Standard Rail Applicationsâ [MNDOT06] ................................... 39 Table 8. EN 1317 Containment Levels Pertaining to Bridge Railings ........................................................................ 45 Table 9. Austrian containment level selection guidelines. ........................................................................................... 46 Table 10 Alberta Canada Roadside Design Guide Bridge Rail Specifications ............................................................ 47 Table 11. Bridge Height and Occupancy Factors ........................................................................................................ 49 Table 12. German bridge railing selection guidelines. ................................................................................................ 51 Table 13. Composition of Traffic by Category. [Italy11] ............................................................................................ 52 Table 14. Bridge Railings and Other Roadside Barriers by Traffic Category. [Italy11] ............................................. 52 Table 15. Summary of R350 Bridge Railing Selection by Highway Function. ........................................................... 55 Table 16. Summary of R350 Bridge Rail Selection Guidelines for Heavy Vehicle Accommodation. ........................ 56 Table 17. Summary of R350 Bridge Rail Selection Guidelines by Combination of Selectors. ................................... 56 Table 18. Summary of R350 Bridge Rail Selection Guidelines by Geometric Design Considerations. ...................... 57 Table 19. Barrier Performance in Narrow Bridge Crashes. [FHWA83] ...................................................................... 58 Table 20. Penetration and rollover percentage in Texas bridge railing crashes. [Mak94] ........................................... 60 Table 21. Crash Costs used in BCAP. [AASHTO89] ................................................................................................. 64 Table 22. Question 2 Average Values. ........................................................................................................................ 73 Table 23. New Jersey Turnpike Crash Severity Distribution. ..................................................................................... 84 Table 24. NJTA After Barrier Contact Behavior. ........................................................................................................ 84 Table 25. Massachusetts Crash Severity Distribution. ................................................................................................ 85 Table 26. Massachusetts After Barrier Contact Behavior. ........................................................................................... 86 Table 27. Washington State Crash Severity Distribution. ........................................................................................... 86 Table 28. Washington State After Barrier Contact Behavior. ..................................................................................... 86 Table 29. Pennsylvania Crash Severity Distribution. .................................................................................................. 88 Table 30. Pennsylvania Bridge Rail After Barrier Contact Behavior. ......................................................................... 88 Table 31. Ohio Crash Severity Distribution. ............................................................................................................... 91 Table 32. Ohio Bridge Rail After Barrier Contact Behavior. ...................................................................................... 92 Table 33. Nebraska Crash Severity Distribution. ........................................................................................................ 93 Table 34. Nebraska Bridge Rail After Barrier Contact Behavior. ............................................................................... 94 Table 35. Severity Distributions for After Penetration Hazards .................................................................................. 95 Table 36. Total Encroachment Frequency by AADT and Highway Type. .................................................................. 96 Table 37. Percetile of Gross Truck Weights for Classes 5 and 9. After [MEPDG04] ................................................. 98 Table 38. Vehicle Mix Used in RSAP to Develop the Guidelines. ........................................................................... 100 Table 39. Vehicle Properties Used in RSAPv3. ........................................................................................................ 101 Table 40. National Traffic Volumes, Crashes, and Crash Rates by Year. ................................................................. 105 Table 41. NHTSA FARS/GES Crash Data and Crash Rates. .................................................................................... 105 Table 42. National Heavy Vehicle Crashes Per 100MVMT. .................................................................................... 106 Table 43. NJ Turnpike Ran Off Road Left Crash Rates, 2005. ................................................................................. 107 Table 44. NJ Turnpike Ran Off Road Left Crash Rates, 2006. ................................................................................. 108 Table 45. NJ Turnpike Ran Off Road Left Crash Rates, 2007. ................................................................................. 109
viii Table 46. NJ Turnpike Ran Off Road Left Crash Rates, 2008. ................................................................................. 110 Table 47. Truck/Bus Crash Rate Multipliers, by Year and Link. .............................................................................. 111 Table 48. Grade (Fgrade) Adjustment Factor. .............................................................................................................. 112 Table 49. Horizontal Curve (Fhcurv) Adjustment Factor. ............................................................................................ 112 Table 50. Bridge Railing Load Capacities. ................................................................................................................ 116 Table 51. RSAPv3 Predictions of Penetration and Rollovers compared to NCHRP 22-08 TXDOT Crash Data. .... 118 Table 52. Comparison to Crash Data of RSAPv3 predictions of Penetrating, Rolling over or Vaulting the Bridge Railing for all Vehicle Classes. ............................................................................................................ 119 Table 53. Comparison of 1988-1990 TXDOT Bridge Crash Data for bridges built after 1965 with RSAPv3 Predictions for MASH TL3. ................................................................................................................. 119 Table 54. EFCCR65 of Longitudinal Barriers used in RSAPv3.[after Ray12] ........................................................... 120 Table 55. Bridge Railing Penetration Hazard Severities. .......................................................................................... 122 Table 56. Crash Cost Adjustments by State to the National Average. [After Bahar11] ............................................ 127 Table 57. Comprehensive Crash Costs by Year. ....................................................................................................... 130 Table 58. National Average Construction Costs for Closed-Profile Concrete Bridge Railings. ............................... 132 Table 59. Annual Number and 2005 Cost of Truck Crash by Injury Severity and Truck Type. [After Zaloshnja06] .............................................................................................................................................................. 134 Table 60. 2005 Cost of All Truck Crashes by Injury Severity and per Victim. [After Zaloshnja06] ........................ 135 Table 61. NSC Economic Impact Crash Costs.[NSC11] ........................................................................................... 136 Table 62. Summary of the Cost of Bridge Rail Crashes in the Media. ...................................................................... 136 Table 63. Summary of the Cost of Bridge Rail Crashes Investigated by NTSB. ...................................................... 137 Table 64. Minimum Radius and Maximum Degree of Curve Based on the Horizontal Sight Distance Obstruction from a TL4 or TL5 Bridge Railing. ...................................................................................................... 140 Table 65. Police Reported Crash Severity by Crash Cost and EFCCR. .................................................................... 146 Table 66. Probability a Collision Will Result in a Severe or Fatal Injury by Hazard Environment and MASH Test Level. ................................................................................................................................................... 149 Table 67. Encroachment Adjustments. ...................................................................................................................... 154 Table 68. AADT â Lifetime Encroachments per 1,000-ft of Bridge Railing. ........................................................... 155 Table 69. Comparison of Impact Conditions for Report 350 and MASH ordered by Impact Severity. .................... 161 Table 70. Approximate Crash Test Acceptance Equivalencies. [after Horne97] ...................................................... 165 Table 71. Selected Examples of Existing Bridge Railings Compared to the Recommended Selection Guidelines. . 169
ix LIST OF FIGURES Figure 1. Mileage of Public Roads and Bridges. ........................................................................................................... 3 Figure 2. Miles of Urban and Rural Bridges.................................................................................................................. 4 Figure 3. Tractor trailer truck which penetrated the Wiehlthal Bridge, Germany. [Wiehltal04] ................................... 5 Figure 4. Damaged W-beam bridge rail and final position of truck on local road under bridge, Avon, CO. [Avon12] 7 Figure 5. Beaverton Bridge Rail Before Crash, Beaverton, OR. [Google Earth] .......................................................... 8 Figure 6. Bronx River Parkway, near crash site, Bronx, NY. [GoogleEarth]. ............................................................... 9 Figure 7. Close-Up of Bridge Rail Type (upper left) and Exit 26 Ramp Truck, Boston, MA. [Google Earth] ........... 11 Figure 8. Gates Bridge, Galesburg, IL. [Google Earth] ............................................................................................... 12 Figure 9. Hazardous material truck crash near Houston, Texas in 1976. [NTSB77e] ................................................. 15 Figure 10. Crash site in Elkridge, MD where a fuel truck penetrated a concrete bridge railing. [NTSB09a] ............. 16 Figure 11. Final rest position of a school bus that penetrated a concrete bridge railing near Huntsville, AL in 2006. [NTSB09b] ............................................................................................................................................. 17 Figure 12. Site of a motorcoach bus crash in Sherman, TX, 2008. [NTSB09c] .......................................................... 18 Figure 13. Instrumented crash wall. [Noel81] ............................................................................................................. 22 Figure 14. The only crash-tested TL6 bridge railing. [Hirsch85] ................................................................................ 26 Figure 15. 50,000-lbs tractor-trailer impacting a 42-inch vertical wall bridge railing. ] ............................................. 26 Figure 16. Portion of the Alberta bridge rail severity index selection table. [Alberta11b] .......................................... 50 Figure 17. Distribution of Reponses to Question 2. ..................................................................................................... 73 Figure 18. Distribution of Question 10 Results. .......................................................................................................... 78 Figure 19. Ohio Standard Drawing BR-1 [OH11a] ..................................................................................................... 90 Figure 20. Mean Axle Load by Vehicle Classification. ............................................................................................... 99 Figure 21. RSAPv3 Crash Prediction Module Flow Chart. ....................................................................................... 115 Figure 22. Lane Mile Cost Comparison by State. [after WSDOT09] ........................................................................ 126 Figure 23. Regional Crash Cost and Construction Cost Adjustment Factors Relative to a Base of One................... 128 Figure 24. NHCCI Index for 2003 through 2010. ..................................................................................................... 129 Figure 25. Comparison of Annual VSL to NHCCI Index Updates. .......................................................................... 131 Figure 26. Minimum Horizontal Curve Radius Based on Barrier Obstruction to the Stopping Sight Distance Compared to AASHTO Exhibit 3-14. .................................................................................................. 139 Figure 27. Cooper Encroachment Frequency Data [after Ray12] .............................................................................. 145 Figure 28. Cooper Encroachment Rate by Lane Volume. [after Ray12] ................................................................... 145 Figure 29. Cumulative EFCCR Distribution for TL2 and TL5 Bridge Railings with 40% Trucks. .......................... 147 Figure 30. AADT â Lifetime Encroachments/1,000-ft of Bridge Railing Nomograph. ............................................ 156 Figure 31. Minimum Horizontal Curve Radius Based on Barrier Obstruction to the Stopping Sight Distance Compared to AASHTO Exhibit 3-14. .................................................................................................. 157 Figure 32. Test Level Selection Nomograph (Risk<0.01 in 30 years for 1000 ft of bridge railing). ......................... 158 Figure 33. Comparison of 89GSBR, NCHRP22-08 with Risk values. ...................................................................... 166 Figure 34. 89GSBR, NCHRP22-08 with BCR values. .............................................................................................. 167 Figure 35. 89GSBR, Risk and BCR comparison. ...................................................................................................... 168 Figure 36. Test Level Selection Nomograph (Risk<0.005 in 30 years for 1000 ft of bridge railing). ....................... 176 Figure 37. Test Level Selection Nomograph (Risk<0.02 in 30 years for 1000 ft of bridge railing). ......................... 177 Figure 38. Test Level Selection Nomograph (Benefit-Cost Ratio=1). ...................................................................... 178 Figure 39. Test Level Selection Nomograph (Benefit-Cost Ratio=2). ...................................................................... 179 Figure 40. Test Level Selection Nomograph (Benefit-Cost Ratio=3). ...................................................................... 180 Figure 41. Rehabilitation Nomograph: Upgrade from R350 TL4 to MASH TL5.* .................................................. 181 Figure 42. Rehabilitation Nomograph: Upgrade from R350 TL3 to MASH TL4 or MASH TL5.* ......................... 182 Figure 43. Rehabilitation Nomograph: Upgrade from R350 TL3 to MASH TL5. .................................................... 183
