Hampton Roads Regional Bridge Study

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SUFFICIENCY RATING 31 SUFFICIENCY RATING Sufficiency ratings are numerical ratings for each bridge based on its structural evaluation, design and function, and public importance. These components are used to obtain a numeric value between 0% and 100%, with a sufficiency rating of 100% representing an entirely sufficient bridge. Similar to structurally deficient bridges, however, it must be emphasized that those bridges with low sufficiency ratings are not necessarily unsafe. Sufficiency ratings are often misunderstood as solely reflecting the condition of a bridge. Instead, the Federal Highway Administration (FHWA) designed sufficiency ratings to cover many aspects of the bridge (including condition) in order to prioritize federal bridge funds for allocation. Deficient bridges with sufficiency ratings of less than 50 qualify for federal bridge replacement funds, while deficient bridges with sufficiency ratings greater than 50 and less than or equal to 80 qualify for federal bridge rehabilitation funds. This is described in more detail in the Bridge Funding section of this report. The sufficiency rating is comprised of three weighted components totaling 100%, plus one component for special reductions. The four components, which are shown in Figure 11, are: SUFFICIENCY RATING SUMMARY Bridges in Hampton Roads with a sufficiency rating of less than 50 Hampton Roads rank among comparable metropolitan areas in terms of the percentage of bridges with a sufficiency rating of less than 50 STRUCTURAL ADEQUACY AND SAFETY (55% MAXIMUM) Superstructure Substructure Culverts Inventory Rating 86/7.0% 75/6.1% in 2007 17 th highest of 35 areas Structural Adequacy and Safety (55%) – This includes the condition of the superstructure, substructure, or culvert. Serviceability and Functional Obsolescence (30%) – This includes thirteen factors related to the design and function of the bridge. Essentiality for Public Use (15%) – This includes traffic volumes carried on the structure, detour length, and the importance of the route carried by the structure for military deployment. Special Reductions (up to 13% reduction) – The sufficiency rating can be reduced based on the type of structure, safety features on the bridge, and detour length. SERVICEABILITY AND FUNCTIONAL OBSOLESCENCE (30% MAXIMUM) Lanes on structure Traffic Volumes Appr. Roadway Width Structure Type Deck Condition Deck Geometry Underclearances Structural Evaluation Waterway Adequacy Bridge Roadway Width STRAHNET designation Approach Roadway Align. Vertical Clear. Over Deck ESSENTIALITY FOR PUBLIC USE (15% MAXIMUM) STRAHNET designation Detour Length Traffic Volumes SPECIAL REDUCTIONS (UP TO 13% MAX. REDUCTION) Detour Length Safety Features Structure Type FIGURE 11 – SUFFICIENCY RATING FACTORS AND COMPONENTS HAMPTON James City/Williamsburg/York ROADS REGIONAL Transportation BRIDGE STUDY Study
SUFFICIENCY RATING 32 The method for calculating bridge sufficiency ratings is complex. Scores for each of the four components are determined based on the variety of factors shown in Figure 11. The method for calculating bridge sufficiency ratings and an example for calculating the sufficiency rating of the High Rise Bridge is shown in Appendix C. The median sufficiency rating for bridges in Hampton Roads is 83.9 as of August 2012. Among the 1,223 bridges in Hampton Roads, 86 bridges (7.0%) have a sufficiency rating of less than 50 (Figure 12). Another 428 bridges (35.0%) in Hampton Roads have a sufficiency rating between 50 and 80. FIGURE 12 – BRIDGE SUFFICIENCY RATINGS IN HAMPTON ROADS Source: HRTPO analysis of VDOT and FHWA data. Data for Hampton Roads bridges as of August 2012. 22 ND STREET BRIDGE HRTPO Table 8 shows the bridge sufficiency ratings by jurisdiction. Suffolk (17 bridges), Isle of Wight County (16), and Southampton County/Franklin (15) have the highest number of bridges with sufficiency ratings less than 50. Combined, these three jurisdictions have more than half of all bridges in Hampton Roads with sufficiency ratings less than 50. The number of bridges in Hampton Roads with a sufficiency rating of less than 50 has increased since the previous Regional Bridge Study. In August 2007, 75 bridges in Hampton Roads had a sufficiency rating of less than 50, comprising 6.1% of all bridges. Total Number Sufficiency Rating Jurisdiction of Bridges 0 - 49.9 50.0 - 80.0 80.1 - 100 N/A CHESAPEAKE 166 12 32 121 1 GLOUCESTER 24 4 9 11 - HAMPTON 83 3 37 43 - ISLE OF WIGHT 85 16 35 34 - JAMES CITY 62 4 26 32 - NEWPORT NEWS 87 3 35 49 - NORFOLK 188 2 60 126 - POQUOSON 0 - - - - PORTSMOUTH 41 2 13 26 - SOUTHAMPTON/FRANKLIN 138 15 49 74 - SUFFOLK 135 17 33 85 - SURRY 32 1 15 16 - VIRGINIA BEACH 118 6 52 60 - WILLIAMSBURG 12 - 6 6 - YORK 52 1 26 25 - HAMPTON ROADS 1,223 86 428 708 1 TABLE 8 – BRIDGE SUFFICIENCY RATINGS IN HAMPTON ROADS BY JURISDICTION Source: HRTPO analysis of VDOT and FHWA data. Data for Hampton Roads bridges as of August 2012. HAMPTON James City/Williamsburg/York ROADS REGIONAL Transportation BRIDGE STUDY Study
Page 1 and 2: Hampton Roads Regional Bridge Study
Page 3 and 4: NON-VOTING MEMBERS: HAMPTON ROADS T
Page 5 and 6: REPORT DOCUMENTATION ii TITLE: Hamp
Page 7 and 8: TABLE OF CONTENTS iv LIST OF FIGURE
Page 9 and 10: INTRODUCTION 2 Health Index -
Page 11 and 12: BRIDGE DEFINITIONS 4 1 - SLAB 99 br
Page 13 and 14: REGIONAL BRIDGE SUMMARY 6 BRIDGES B
Page 15 and 16: REGIONAL BRIDGE SUMMARY 8 Bridges i
Page 17 and 18: BRIDGE INSPECTIONS AND RATINGS 10 E
Page 19 and 20: DEFICIENT BRIDGES 12 STRUCTURALLY D
Page 21 and 22: DEFICIENT BRIDGES 14 Federal Struct
Page 23 and 24: DEFICIENT BRIDGES 16 FUNCTIONALLY O
Page 25 and 26: DEFICIENT BRIDGES 18 Jurisdiction F
Page 33 and 34: DEFICIENT BRIDGES 26 DEFICIENT BRID
Page 35 and 36: DEFICIENT BRIDGES 28 WEIGHT-POSTED
Page 37: FRACTURE AND SCOUR CRITICAL BRIDGES
Page 41 and 42: SUFFICIENCY RATING 34 Jurisdiction
Page 43 and 44: HEALTH INDEX 36 HEALTH INDEX As des
Page 45 and 46: BRIDGE FUNDING 38 Non-federal-aid
Page 47 and 48: BRIDGE FUNDING 40 restrictions, suf
Page 49 and 50: BRIDGE FUNDING 42 Bridge, Pinners P
Page 51 and 52: BRIDGE PROJECTS 44 Federal Structur
Page 53 and 54: BRIDGE PROJECTS 46 A total of $781
Page 55 and 56: COST OF SUSTAINING BRIDGE CONNECTIO
Page 61 and 62: CONCLUSIONS 54 CONCLUSIONS Based on
Page 63 and 64: APPENDIX A 56 National Bridge Inven
Page 65 and 66: APPENDIX B 58 DECK, SUPERSTRUCTURE,
Page 67 and 68: APPENDIX B 60 INVENTORY RATING The
Page 69 and 70: APPENDIX B 62 UNDERCLEARANCES This
Page 71 and 72: APPENDIX B 64 APPROACH ROADWAY ALIG
Page 73 and 74: APPENDIX C 66 COMPONENT #1 - STRUCT
Page 75 and 76: APPENDIX C 68 If none of those four
Page 77 and 78: APPENDIX C 70 COMPONENT #4 - SPECIA
Page 79 and 80: APPENDIX D 72 Ü CHESAPEAKE BRIDGES
Page 81 and 82: APPENDIX D 74 Federal Structure ID
Page 89 and 90:
APPENDIX D 82 Ü ISLE OF WIGHT COUN
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APPENDIX D 84 Federal Structure ID
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APPENDIX D 88 Ü NEWPORT NEWS BRIDG
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Hampton Roads Regional Bridge Study

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