State Bridge Load Posting Processes and Practices (2014)

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5 This chapter presents information from the National Bridge Inventory (NBI) for reporting year 2012 (1) that identifies bridges and culverts that are posted for load, and shows the distributions of load posted structures among attributes such as owner, route system, structures type, and general condition. Distributions of load posted structures are presented for 24 attributes available in the NBI. Examination of these dis- tributions yields some general findings: Prevalence Ten percent of bridges and culverts on U.S. roads are posted for load. Owner Eighty percent of load posted bridges and culverts are owned by local governments. In 27 U.S. states, less than 1% of state-owned structures are posted for load. Route System Ninety-one percent of load posted bridges and culverts are on rural roads, 76% of posted structures are on low-volume roads, and 79% of load posted structures carry fewer than 20 trucks per day. Less than 1% of structures on interstate routes are posted for load. Condition Seventy-five percent of load posted bridges and culverts are in fair or good general condition. Age Eighty-eight percent of load posted bridges and culverts were built before 1980. Design Load Seventy-seven percent of load posted bridges and culverts have unknown design live load or were designed for live load equal to or less than H15. Structure Type Ninety-five percent of load posted structures are bridges, not culverts. Among bridges, 12% are posted for load, and among cul- verts, 2% are posted for load. Load Rating Method Ninety-three percent of load posted bridges and culverts have load ratings determined by computational methods. Seven percent of load posted structures have load rating determined by field evaluation and engineering judgment (FE/EJ), or lack load rating analysis. Load tests are used for less than 1% of load ratings. U.S. NATIONAL BRIDGE INVENTORY Every year, U.S.DOT collects data from state governments on their inventories of bridges and culverts. These data, the NBI, are publically available as a set of fixed format text files (2). The NBI includes 116 data items that list structure loca- tions, owners, types, conditions, uses, and status as structur- ally deficient or functionally obsolete (3). The NBI identifies bridges and culverts that are posted for load. Several data items are useful to an examination of load posting among U.S. bridges and culverts (Table 1). One field, NBI item 41, is used in this synthesis report as a dependent variable. Item 41 reports that a structure is open, closed, or posted for load. Coding ‘P’ for item 41 indicates that a struc- ture is posted for load. The tables in this synthesis list the counts and percentages of ‘P’ structures within categories defined by structure owner, route, structure type, condition, and status. LOAD POSTING AND BRIDGE OWNER There are more than 61,000 bridges and culverts posted for load among the 610,000 structures reported in the NBI (Table 2). NBI records include 50 state governments plus the District of Columbia and Puerto Rico. Among these 52 gov- ernments, a median of 7% of bridges and culverts are posted for load; the maximum is 27% percent, and the minimum is slightly more than 1%. More than 80% of structures posted for load are owned by local governments (Table 3), and are part of local gov- ernment roads. Posted structures on county highways make up nearly three of four U.S. structures posted for load (Table 4). LOAD POSTING AND ROUTE SYSTEM Less than 1% of structures on interstate routes and U.S. num- bered routes are posted for load. Five percent of structures on state highways are posted for load. Less than 10% of structures posted for load are on the base network of high- ways (Table 5), less than 3% are on the designated national highway network for trucks (Table 6), less than 1% are on the chapter one STATUS OF BRIDGE POSTING FOR LOAD IN THE UNITED STATES

6 TABLE 1 NBI DATA ITEMS EXAMINED FOR CORRELATION WITH LOAD POSTING Item Title Note 1 State code Federal Information Processing Standards (FIPS) codes for states 5B Route signing prefix Interstate, U.S. highway, state highway, county road, city street, federal lands road, state lands road 5C Designated level of service Mainline, alternate, bypass, spur, business, ramp/wye/connector, service/frontage road 12 Base highway network On/off base highway network 20 Toll Toll status of the bridge 22 Owner Owner(s) of the bridge 26 Functional classification of inventory route Arterial, collector, or local; urban or rural 27 Year built Year of construction 29 Average daily traffic Average daily count of vehicles crossing the bridge 31 Design load Live load for which the bridge was designed 37 Historical significance Bridge’s listing, if any, on a register of historic places 41 Structure open, posted, or closed to traffic Operational status of a bridge 43 Structure type, main Kind of material, type of design 58 Deck condition General condition rating 59 Superstructure condition General condition rating 60 Substructure condition General condition rating 62 Culvert condition General condition rating 63 Method used to determine operating rating Method of load rating, or absence of analysis 65 Method used to determine inventory rating Method of load rating, or absence of analysis 70 Bridge posting Comparison of operating rating to state legal loads 92A Fracture critical (FC) details Yes/no for presence of FC details in bridge 100 STRAHNET highway designation On/off STRAHNET 104 National Highway System On/off National Highway System 110 Designated national network On/off national network for trucks SD Status Yes/no structurally deficient, functionally obsolete Source: Recording and Coding Guide for the Structure Inventory and Appraisal of the Nation’s Bridges (3). STRAHNET = Strategic Highway Network. TABLE 2 LOAD POSTING, STATE CODE AND BRIDGE OWNER All Structures State Owned Locally Owned Count Structures 609,728 293,870 305,505 Posted for Load 61,038 10,045 50,170 Percentage Posted for Load, FIPS Average 10.0 3.4 16.4 Posted for Load, FIPS Median 6.9 0.91 12.6 Posted for Load, FIPS Maximum 27.2 20.4 34.5 Posted for Load, FIPS Minimum 1.2 0.02 0.00 FIPS = Federal Information Processing Standards.

7 TABLE 3 LOAD POSTING AND BRIDGE OWNER Item 22 Owner Structures Posted for Load % of Owner % of Load Posted Federal Government 8,890 515 5.8 0.84 State Government 293,870 10,045 3.4 16.5 Local Government 305,505 50,170 16.4 82.2 Other 1,449 306 21.1 0.50 TABLE 4 LOAD POSTING AND ROUTE SIGNING PREFIX Item 5B Route Signing Prefix Structures Posted for Load % by Route % of Load Posted Interstate Highway 55,981 147 0.26 0.24 U.S. Numbered Highway 54,218 510 0.94 0.84 State Highway 147,441 7,392 5.0 12.1 County Highway 259,656 44,884 17.3 73.5 City Street 68,222 6,003 8.8 9.8 Federal Lands Road 7,175 312 4.3 0.51 State Lands Road 1,135 195 17.2 0.32 Other 15,892 1,595 10.0 2.6 TABLE 5 LOAD POSTING AND BASE HIGHWAY NETWORK Item 12 Base Highway Network Structures Posted for Load % of System % of Load Posted Inventory Route Is Not on the Base Network 412,817 55,991 13.6 91.7 Inventory Route Is on the Base Network 150,527 2,967 2.0 4.9 TABLE 6 LOAD POSTING AND DESIGNATED NATIONAL NETWORK Item 110 Designated National Network Structures Posted % of System % of Load Posted Not Part of the National Network for Trucks 513,827 59,531 11.6 97.5 Part of the National Network for Trucks 95,896 1,506 1.6 2.5 TABLE 7 LOAD POSTING AND HIGHWAY SYSTEM Item 104 Highway System of the Inventory Route Structures Posted % of System % of Load Posted Inventory Route Is Not on the NHS 491,984 60,540 12.3 99.2 Inventory Route Is on the NHS 117,743 497 0.4 0.8 LOAD POSTING AND ROUTE SERVICE More than 90% of structures posted for load are on rural routes (Table 10). Nearly 90% of structures posted for load are on mainline routes (Table 11), nearly 76% of load posted struc- tures carry low-volume roads (Table 12), and nearly 79% of load posted structures carry fewer than 20 trucks per day (Table 13). LOAD POSTING, BRIDGE CONDITION, AND AGE Nearly 40% of bridges and culverts built before year 1900 are posted for load (Table 14). Less than 2% of structures built since 2000 are posted for load. The fraction of structures that are posted for load increases with age. About 30% of structures on national or state registries of historic bridges are posted for load (Table 15). More than 70% of load posted structures are not yet historically significant. National Highway System (NHS) (Table 7), and less than 1% are on the strategic highway network (STRAHNET) (Table 8). Less than 1% of structures posted for loads carry toll roads (Table 9). [Note: The federal transportation bill Moving Ahead for Progress in the 21st Century Act (MAP-21) (4) changed the extent of the NHS. NBI data for year 2012 do not include this change.]

8 TABLE 11 LOAD POSTING AND LEVEL OF SERVICE Item 5C Designated Level of Service Structures Posted for Load % of Level of Service % of Load Posted None of the Below 60,629 5,164 8.5 8.5 Mainline 517,182 54,114 10.5 88.7 Alternate 7,250 872 12.0 1.4 Bypass 1,204 17 1.4 0.0 Spur 2,414 137 5.7 0.2 Business 2,548 180 7.1 0.3 Ramp, Wye, Connector, etc. 11,878 64 0.5 0.1 Service/Frontage Road 6,622 490 7.4 0.8 TABLE 8 LOAD POSTING AND STRAHNET Item 100 STRAHNET Highway Designation Structures Posted % of Group % of Load Posted Not a STRAHNET Route 541,477 60,854 11.2 99.7 Interstate STRAHNET Route 56,952 155 0.27 0.25 Non-Interstate STRAHNET Route 10,314 24 0.23 0.04 STRAHNET Connector Route 984 4 0.41 0.01 LOAD POSTING AND GENERAL CONDITION RATINGS General condition ratings (GCR) in the NBI are reported on a 9 to 0 scale. Rating 9 indicates the best condition. The AASHTO Manual for Bridge Evaluation (MBE) (5) relates NBI general condition ratings to “good,” “fair,” and “poor” categories of condition. General condition ratings of 6 and higher reflect good condition, a rating of 5 is considered fair condition, and ratings of 4 and lower are designated poor. Most bridges posted for load are in good or fair condition. Among load posted structures, 88% have decks in good or fair condition (Table 16), 83% have superstructures in good or fair condition (Table 17), and 75% have substructures in good or fair condition (Table 18). Most culverts posted for load are in good or fair condition (Table 19). Forty-eight percent of load posted structures are structur- ally deficient, and 17% are functionally obsolete (Table 20). LOAD POSTING, BRIDGE TYPE, AND DESIGN LOAD Twenty-nine percent of structures posted for load were designed for AASHTO H15 live load or less (Table 21). The design load is not known for 57% of structures posted for load. The ten most numerous structure types, and load posted counts for Item 20 Toll Structures Posted for Load % of Route % of Load Posted Toll Routes 7,678 89 1.2 0.1 Free Routes 601,951 60,947 10.1 99.9 TABLE 9 LOAD POSTING AND TOLL BRIDGES TABLE 10 LOAD POSTING AND FUNCTIONAL CLASS Item 26 Functional Class Structures Posted for Load % of Functional Class % of Load Posted Rural Arterial 101,083 1,030 1.0 1.7 Collector 141,366 14,269 10.1 23.4 Local 206,364 40,028 19.4 65.6 Urban Arterial 107,597 1,700 1.6 2.8 Collector 20,641 1,090 5.3 1.8 Local 32,673 2,921 8.9 4.8 Total Arterial 208,680 2,730 1.3 4.5 Collector 162,007 15,359 9.5 25.2 Local 239,037 42,949 18.0 70.4

9 each, are shown in Table 22. The top ten counts of load posted bridges and culverts by structure type are shown in Table 23. More than 35% of bridges with fracture critical details are posted for load (Table 24). Structures and load posted structures having design load equal to or less than H15 are listed by structure material in Table 25. LOAD POSTING AND METHOD OF LOAD RATING NBI uses 15 codes to identify methods of load rating. Of these, 12 codes indicate methods of computational structural analysis, one indicates load testing, and two indicate neither analysis nor testing. FE/EJ, NBI code 0, is a documented evaluation of safe load capacity (6). FE/EJ is used when design plans for structures are not available. No rating analysis, NBI code 5, is the absence of a load rating or of documentation of a load rating. More than 50% of load posted structures are load rated using the allowable stress method (Tables 26 and 27). LOAD RATING METHOD—DETAILS ON BRIDGES AND CULVERTS Ninety percent of bridges have load ratings determined by computation. Eighty-nine percent of bridges that are posted for load have load ratings determined by computation (Table 28). Less than 10% of bridges that have load ratings determined by FE/EJ, or by load tests, or that lack load rating analysis, are posted for load. Fifty-two percent of culverts have load ratings determined by computation (Table 29). Seventy-nine percent of culverts that are posted for load have load ratings determined by computation. LOAD POSTING AND OPERATING RATING Fifty-four percent of bridges and culverts that are posted for load have an operating load rating of less than 50 kips, the gross vehicle weight (GVW) of the lightest truck among AASHTO legal load rating vehicles (5) (Table 30). TABLE 12 LOAD POSTING AND ADT Item 29 ADT Structures Posted for Load % of Group % of Load Posted Fewer than 400 243,573 46,198 19.0 75.7 400 to 999 71,381 6,656 9.3 10.9 1,000 to 4,999 127,446 5,555 4.4 9.1 5,000 to 9,999 58,345 1,189 2.0 1.9 10,000 to 49,999 88,965 1,106 1.2 1.8 50,000 and Greater 18,319 77 0.4 0.1 ADT = average daily traffic. Item 27 Year Built Structures Posted for Load % of Group % of Load Posted 1697 to 1899 1,847 733 39.7 1.2 1900 to 1919 14,418 4,947 34.3 8.1 1920 to 1939 66,406 14,926 22.5 24.5 1940 to 1959 97,398 16,164 16.6 26.5 1960 to 1979 188,847 17,180 9.1 28.1 1980 to 1999 160,742 5,984 3.7 9.8 2000 to 2012 80,061 1,103 1.4 1.8 TABLE 14 LOAD POSTING AND YEAR BUILT ADTT (count) Structures Posted for Load % of Group % of Load Posted 0 or Not Reported 159,708 27,968 17.5 45.8 1 to 19 121,652 20,402 16.8 33.4 20 to 99 90,849 7,704 8.5 12.6 100 to 499 104,534 3,474 3.3 5.7 500 to 4,999 112,742 1,380 1.2 2.3 5,000 and More 20,390 110 0.5 0.2 ADTT = average daily truck traffic. TABLE 13 LOAD POSTING AND ADTT Item 37 Historical Significance Structures Posted for Load % of Group % of Load Posted On National Register of Historic Places 1,806 593 32.8 0.97 Eligible for National Register of Historic Places 4,258 1,269 29.8 2.1 On a State or Local Historic Register 15,223 5,165 33.9 8.5 Not Determinable 92,344 8,963 9.7 14.7 Not Eligible for National Register of Historic Places 496,075 45,048 9.1 73.8 TABLE 15 LOAD POSTING AND HISTORICAL SIGNIFICANCE

10 SUMMARY ON STATUS OF LOAD POSTING NBI records were examined for the counts and distribu- tions of load posted bridges and culverts. Ten percent of U.S. bridges and culverts are posted for load. On interstate routes, less than 1% of structures are posted for load. On state highways, 5% of structures are load posted. On roads owned by local governments, 16% of structures are posted for load. Local governments own 82% of all U.S. structures posted for load, and state governments own 16%. The distribution of load posted structures among states is non-uniform. In 27% states, less than 1% of state-owned structures are posted for load. Seventy-six percent of bridges and culverts posted for load have average daily traffic (ADT) of fewer than 400 vehi- cles, and 82% have average daily truck traffic (ADTT) of fewer than 100 trucks. Thirty-three percent of historic structures are posted for load, and 40% of structures built before 1900 are load posted. Eighty-eight percent of load posted structures were built before 1980. Load posting is more frequent among structures in poor general condition; however, structures in poor condition are not numerous. As a result, most load posted bridges are in good or fair general condition. Among load posted bridges, general conditions are fair or good for decks (88%), for superstructures (83%), or for substructures (75%). Ninety-five percent of load posted structures are bridges, not culverts. Fifty-two percent of timber beam bridges are load posted, and timber beam bridges are 15% of all load posted structures. The design live load is not known for 57% of load posted structures. Fifty-one percent of load posted structures have oper ating load ratings computed by the allowable stress method. Ninety-three percent of load posted bridges and culverts have load ratings determined by computational methods. Item 62 Culvert Condition Structures Posted % of Group % of Load Posted Good 120,749 1,865 1.5 3.1 Fair 11,016 463 4.2 0.76 Poor 3,075 368 12.0 0.60 TABLE 19 LOAD POSTING AND CULVERT CONDITION Item 60 Substructure Condition Structures Posted % of Group % of Load Posted Good 381,562 26,706 7.0 45.8 Fair 61,217 17,056 27.9 29.3 Poor 31,897 14,537 45.6 24.9 TABLE 18 LOAD POSTING AND SUBSTRUCTURE CONDITION Item 59 Superstructure Condition Structures Posted % of Group % of Load Posted Good 392,827 31,564 8.0 54.1 Fair 57,263 16,762 29.3 28.7 Poor 24,515 9,982 40.7 17.1 TABLE 17 LOAD POSTING AND SUPERSTRUCTURE CONDITION Item 58 Deck Condition Structures Posted % of Group % of Load Posted Good 387,001 35,272 9.1 61.0 Fair 59,745 15,736 26.3 27.2 Poor 22,960 6,780 29.5 11.7 TABLE 16 LOAD POSTING AND DECK CONDITION Structure Status Structures Posted % of Group % of Load Posted Structurally Deficient 65,599 29,005 44.2 47.5 Functionally Obsolete 76,316 10,353 13.6 17.0 Not Deficient, Not Obsolete 465,291 21,475 4.6 35.2 Not Applicable 2,522 205 8.1 0.3 TABLE 20 LOAD POSTING AND STRUCTURE STATUS Item 31 Design Load Structures Posted for Load % of Group % of Load Posted M9 or H10 12,179 5,740 47.1 9.4 M13.5 or H15 67,888 10,660 15.7 17.5 MS13.5 or HS15 11,175 1,022 9.1 1.7 M18 or H20 51,375 2,899 5.6 4.7 MS18 or HS20 248,108 5,327 2.1 8.7 MS18+Mod or HS20+Mod 69,032 594 0.9 1.0 Pedestrian 68 3 4.4 0.005 Railroad 169 9 5.3 0.015 MS22.5 or HS25 29,666 89 0.3 0.15 Other or Unknown 115,877 34,673 29.9 56.8 TABLE 21 LOAD POSTING AND DESIGN LOAD

11 Item 43 Structure Type, Main Structures Posted % of Group % of Load Posted Steel Stringer/multi-beam or girder 101,454 22,481 22.2 36.8 Wood or Timber Stringer/multi-beam or girder 18,180 9,373 51.6 15.4 Steel Truss—Thru 9,396 4,927 52.4 8.1 Concrete Slab 33,123 3,907 11.8 6.4 Steel Continuous Stringer/multi-beam or girder 47,005 2,710 5.8 4.4 Concrete Culvert (includes frame culvert) 89,624 2,038 2.3 3.3 Concrete Tee beam 20,295 1,997 9.8 3.3 Steel Girder and floor beam system 3,993 1,630 40.8 2.7 Concrete Channel beam 12,748 1,576 12.4 2.6 Concrete Continuous Slab 31,940 1,489 4.7 2.4 TABLE 23 MOST NUMEROUS POSTED STRUCTURES BY STRUCTURE TYPE Item 43 Structure Type, Main Structures Posted % of Group % of Load Posted Steel Stringer/multi-beam or girder 101,454 22,481 22.2 36.8 Concrete Culvert, includes frame culvert 89,624 2,038 2.3 3.3 Prestressed Concrete Stringer/multi-beam or girder 54,317 383 0.71 0.63 Steel Continuous Stringer/multi-beam or girder 47,005 2,710 5.8 4.4 Prestressed Concrete Box beam or girders—Multiple 40,686 710 1.7 1.2 Concrete Slab 33,123 3,907 11.8 6.4 Concrete Continuous Slab 31,940 1,489 4.7 2.4 Concrete Continuous Culvert, includes frame culvert 27,795 215 0.77 0.35 Concrete Tee beam 20,295 1,997 9.8 3.3 Wood or Timber Stringer/multi-beam or girder 18,180 9,373 51.6 15.4 TABLE 22 TEN MOST NUMEROUS STRUCTURE TYPES AND LOAD POSTING Item 92A Fracture Critical Details Structures Posted % of Group Posted % of Load Yes 20,828 7,440 35.7 12.2 No 588,892 53,597 9.1 87.8 TABLE 24 LOAD POSTING AND FRACTURE CRITICAL DETAILS Structure Material Structures Posted % of Group % of Load Posted Design Load H15 or Lower Concrete 55,057 6,273 11.4 10.3 Prestressed Concrete 6,829 781 11.4 1.3 Steel 23,538 7,392 31.4 12.1 Timber 5,369 2,909 54.2 4.8 Masonry 370 39 10.5 0.1 Aluminum, Iron 56 26 46.4 0.0 Other 22 2 9.1 0.0 TABLE 25 LOAD POSTING AND STRUCTURE MATERIAL FOR DESIGN LOAD H15 OR LOWER

Item 63 Method Used to Determine Operating Rating NBI Code Structures Posted % of Group % of Load Posted Field evaluation and engineering judgment 0 14,294 340 2.4 0.6 Load Factor Rating (LFR) 1 320,833 24,346 7.6 39.9 Allowable Stress Rating (ASR) 2 162,510 31,397 19.3 51.4 Load and Resistance Factor Rating (LRFR) 3 9,934 586 5.9 1.0 Load testing 4 553 37 6.7 0.1 No rating analysis performed 5 95,876 4,109 4.3 6.7 LFR, rating factor, MS18 loading 6 293 1 0.3 0.0 ASR, rating factor, MS18 loading 7 10 0 0.0 0.0 LRFR, rating factor, HL93 loading 8 3,234 221 6.8 0.4 Assigned rating, Load Factor Design in metric tons A 1,327 1 0.1 0.0 Assigned rating, Allowable Stress Design in metric tons B 794 0 0.0 0.0 Assigned rating, Load and Resistance Factor Design in metric tons C 18 0 0.0 0.0 Assigned rating, Load Factor Design, rating factor, MS18 loading D 0 0 — 0.0 Assigned rating, Allowable Stress Design, rating factor, MS 18 loading E 5 0 0.0 0.0 Assigned rating, Load and Resistance Factor Design, rating factor, HL93 loading F 18 0 0.0 0.0 TABLE 26 LOAD POSTING AND METHOD USED TO DETERMINE OPERATING RATING TABLE 27 LOAD POSTING AND METHOD USED TO DETERMINE INVENTORY RATING Item 65 Method Used to Determine Inventory Rating NBI Code Structures Posted % of Group % of Load Posted Field evaluation and engineering judgment 0 14,250 341 2.4 0.6 Load Factor Rating (LFR) 1 320,969 24,355 7.6 39.9 Allowable Stress Rating (ASR) 2 162,694 31,420 19.3 51.5 Load and Resistance Factor rating (LRFR) 3 9,909 581 5.9 1.0 Load testing 4 555 41 7.4 0.1 No rating analysis performed 5 95,613 4,076 4.3 6.7 LF, rating factor, MS18 loading 6 291 1 0.3 0.0 AS, rating factor, MS18 loading 7 11 0 0.0 0.0 LRFR, rating factor, ML93 loading 8 3,237 222 6.9 0.4 Assigned rating, Load Factor Design in metric tons A 1,327 1 0.1 0.0 Assigned rating, Allowable Stress Design in metric tons B 794 0 0.0 0.0 Assigned rating, Load and Resistance Factor Design in metric tons C 18 0 0.0 0.0 Assigned rating, Load Factor Design, rating factor, MS18 loading D 0 0 — 0.0 Assigned rating, Allowable Stress Design, rating factor, MS18 loading E 5 0 0.0 0.0 Assigned rating, Load and Resistance Factor Design, rating factor, HL93 loading F 18 0 0.0 0.0

13 Item 63 Method Used to Determine Operating Rating NBI Code Bridges Posted for Load % of Group % of Posted Bridges Load Rating Computation 1, 2, 3, 6, 7, 8, A, B, C, D, E, F 429,460 54,426 12.7 93.3 Field Evaluation and Engineering Judgment 0 3,684 285 7.7 0.5 No Rating Analysis Performed 5 41,254 3,594 8.7 6.2 Load Testing 4 464 34 7.3 0.1 TABLE 28 LOAD POSTING AND METHOD USED TO DETERMINE OPERATING RATING—BRIDGES ONLY TABLE 29 LOAD POSTING AND METHOD USED TO DETERMINE OPERATING RATING—CULVERTS ONLY Item 63 Method Used to Determine Operating Rating NBI Code Culverts Posted for Load % of Group % of Posted Culverts Load Rating Computation 1, 2, 3, 6, 7, 8, A, B, C, D, E, F 69,509 2,123 3.1 78.7 Field Evaluation and Engineering Judgment 0 10,610 55 0.5 2.0 No Rating Analysis Performed 5 54,611 515 0.9 19.1 Load Testing 4 89 3 3.4 0.1 TABLE 30 LOAD POSTING AND OPERATING RATING Operating Rating Minimum, kip GVW Equivalent Structures Posted for Load % of Group % of Load Posted Less than 6 2,668 2,043 76.6 3.3 6 15,314 13,673 89.3 22.4 30 H15 11,901 7,952 66.8 13.0 40 H20 16,304 9,014 55.3 14.8 50 Type 3 77,610 17,295 22.3 28.3 72 Type 3S2 27,641 3,172 11.5 5.2 80 Type 3-3 170,525 4,988 2.9 8.2 100 and Greater 276,570 2,739 1.0 4.5 Among structures with no load rating analysis or load rating by FE/EJ, 4% are posted for load. ORGANIZATION OF THE SYNTHESIS REPORT This report is presented as a summary, four chapters and two appendices, as follows: Chapter One: Status of Bridge Posting for Load in the United States presents information from the NBI for report- ing year 2012 (1) that identifies bridges and culverts that are posted for load, and shows the distributions of load posted structures among attributes such as owner, route system, structures type, and structure condition. Chapter Two: Management of Load Posting of Bridges and Culverts reports state government authority to post structures for load, the role of state government in load posting of structures owned by local governments, load rating staff at departments of transportation (DOTs), use of safety inspections and general condition ratings in load

14 Definitions, Abbreviations, and Acronyms provides defini- tions of terms, and the meanings of abbreviations and acro- nyms used in this synthesis report. References: A comprehensive listing of the references cited in the text. Appendix A: Survey of States on Practices in Load Posting presents the questionnaire distributed to U.S. state DOTs and the responses from the states. Appendix B: Detailed Information on Fines, Loads, and Vehicles contains tabulations of fines, legal loads, exempt loads, overweight permit loads, and rating vehicles collected from state law and state DOT publications. posting, time intervals to identify and implement load post- ings, quality practices in load posting, signs for weight limits at posted structures, and fines for violation of weight limits. Chapter Three: Methods of Evaluation of Weight Limits for Bridges and Culverts presents details on the legal loads, overweight permit loads, methods of load rating, load rating vehicles, and posting levels used by U.S. states. This chapter reports on research at states related to load posting. Chapter Four: Conclusions and Needs for Further Research presents a brief summary of the synthesis report, notes the boundaries of information in the report and lists areas for additional work.