LLRRFFDD BBrriiddggee DDeessiiggnn MMaannuuaall B R I D G E O F F I C E MINNESOTA DEPARTMENT OF TRANSPORTATION Bridge Office LRFD Bridge Design Manual MANUAL 5-392 Mn/DOT BRI DGE OFFI CE LRFD Bridge Design Manual Minnesota Department of Transportation 3485 Hadley Avenue North Mail Stop 610 Oakdale, MN 55128-3307 Phone: 651/366-4500 Fax: 651/366-4497 JULY 2003 OCTOBER 2003 JANUARY 2004 APRIL 2004 OCTOBER 2004 DECEMBER 2004 FEBRUARY 2005 MARCH 2005 NOVEMBER 2005 MARCH 2006 APRIL 2006 MAY 2006 AUGUST 2006 OCTOBER 2006 FEBRUARY 2007 JUNE 2007 JULY 2007 OCTOBER 2007 APRIL 2008 MAY 2008 JUNE 2008 AUGUST 2008 SEPTEMBER 2008 OCTOBER 2008 APRIL 2009 MAY 2009 OCTOBER 2009 MARCH 2010 JUNE 2010 FEBRUARY 2007 LRFD BRIDGE DESIGN i TABLE OF CONTENTS 1. INTRODUCTION..................................................................................... 1-1 1.1 Overview Of Manual 5-392 ................................................................ 1-1 1.1.1 Material Contained in Manual 5-392 .......................................... 1-1 1.1.2 Updates to Manual 5-392 ......................................................... 1-2 1.1.3 Format of Manual References.................................................... 1-2 1.2 General Bridge Information ............................................................... 1-2 1.2.1 Bridge Office .......................................................................... 1-3 1.2.2 Highway Systems .................................................................... 1-8 1.2.3 Bridge Numbers ...................................................................... 1-8 1.2.4 Limit States to Consider in Design ........................................... 1-11 1.3 Procedures .................................................................................... 1-11 1.3.1 Checking of Mn/DOT Prepared Bridge Plans .............................. 1-11 1.3.2 Checking of Consultant Prepared Bridge Plans .......................... 1-12 1.3.3 Schedule for Processing Construction Lettings .......................... 1-16 1.3.4 Bridge Project Tracking System .............................................. 1-17 1.3.5 Approval Process for Standards............................................... 1-21 2. GENERAL DESIGN AND LOCATION FEATURES ........................................ 2-1 2.1 Geometrics ...................................................................................... 2-1 2.1.1 Bridge Geometrics ................................................................... 2-1 2.1.2 Bridge Deck Requirements ....................................................... 2-2 2.1.3 Bridge Undercrossing Geometrics .............................................. 2-7 2.1.4 Geometric Details ................................................................. 2-15 2.1.5 Bridge Railings ...................................................................... 2-28 2.2 Bridge Aesthetics ........................................................................... 2-28 2.3 Preliminary Bridge Plans ................................................................. 2-28 2.3.1 General ............................................................................... 2-28 2.3.2 Bridge Type Selection ............................................................ 2-38 FEBRUARY 2007 LRFD BRIDGE DESIGN ii 2.4 Final Bridge Plans and Special Provisions ........................................... 2-43 2.4.1 Final Design Instructions ........................................................ 2-44 2.4.1.1 Superstructure ................................................................. 2-45 2.4.1.1.1 Framing Plan ...................................................... 2-45 2.4.1.1.2 Concrete Wearing Course ..................................... 2-46 2.4.1.1.3 Diaphragms and Cross Frames ............................. 2-46 2.4.1.2 Pedestrian Bridges ............................................................ 2-47 2.4.1.3 Temporary Bridges and Widenings ...................................... 2-49 2.4.1.4 Bridge Approaches ............................................................ 2-50 2.4.1.5 Survey ............................................................................ 2-50 2.4.1.6 Utilities ........................................................................... 2-50 2.4.1.7 Precedence of Construction Documents ............................... 2-52 2.4.1.8 Design Calculation Requirements ........................................ 2-52 2.4.2 Final Plans ........................................................................... 2-52 2.4.2.1 Drafting Standards ........................................................... 2-53 2.4.2.2 Drafting Guidelines ........................................................... 2-53 2.4.2.3 General Plan and Elevation ................................................ 2-56 2.4.2.4 Bridge Layout and Staking Plan .......................................... 2-61 2.4.2.5 Standard Abbreviations ..................................................... 2-64 2.4.2.6 Inclusion of Standard Bridge Details in Plan Sets .................. 2-64 2.4.2.7 Use of Bridge Standard Plans ............................................. 2-64 2.4.2.8 Standard Plan Notes ......................................................... 2-64 2.4.2.9 Quantity Notes and Pay Items ............................................ 2-65 2.4.3 Revised Sheets ..................................................................... 2-66 2.5 Reconstruction Guidelines and Details ............................................... 2-67 2.5.1 Superstructure ..................................................................... 2-67 2.5.1.1 Railings ........................................................................... 2-67 2.5.1.2 Wearing Course ................................................................ 2-69 2.5.1.3 Expansion/Fixed Joints ...................................................... 2-69 2.5.2 Substructure ........................................................................ 2-81 2.5.2.1 Abutments ....................................................................... 2-81 2.5.2.2 Piers ............................................................................... 2-81 2.5.3 Pavement ............................................................................ 2-81 FEBRUARY 2007 LRFD BRIDGE DESIGN iii 2.6 Construction Requirements ............................................................. 2-87 APPENDIX 2-A: BRIDGE TYPE NUMBERS ................................................... 2-88 APPENDIX 2-B: SPECIAL PROVISIONS 2005 SPEC. BOOK ......................... 2-89 APPENDIX 2-C: STANDARD ABBREVIATIONS ............................................. 2-92 APPENDIX 2-D: BRIDGE DETAILS PART I (B-DETAILS) ................................ 2-95 APPENDIX 2-E: BRIDGE DETAILS PART II (STANDARD FIGURES) ................. 2-97 APPENDIX 2-F: BRIDGE STANDARD PLANS: CULVERTS ............................... 2-99 APPENDIX 2-G: MN/DOT STANDARD PLANS: SPECIAL STRUCTURES .......... 2-100 APPENDIX 2-H: STANDARD PLAN NOTES ................................................ 2-101 APPENDIX 2-I: STANDARD SUMMARY OF QUANTITIES NOTES ................... 2-110 APPENDIX 2-J: BRIDGE PAY ITEMS ......................................................... 2-112 APPENDIX 2-K: CONVERSION FROM INCHES TO DECIMALS OF A FOOT ...... 2-116 3. LOAD AND LOAD FACTORS .................................................................... 3-1 3.1 Load Factors and Combinations .......................................................... 3-1 3.2 Load Modifiers ................................................................................. 3-3 3.3 Permanent Loads (Dead and Earth) .................................................... 3-4 3.4 Live Loads ....................................................................................... 3-4 3.4.1 HL-93 Live Load, LL ................................................................. 3-5 3.4.2 Multiple Presence Factor, MPF ................................................... 3-5 3.4.3 Dynamic Load Allowance, IM .................................................... 3-5 3.4.4 Pedestrian Live Load, PL .......................................................... 3-5 3.4.5 Braking Force, BR ................................................................... 3-5 3.4.6 Centrifugal Force, CE ............................................................... 3-6 3.4.7 Live Load Application to Buried Structures .................................. 3-6 3.4.8 Live Load Surcharge, LS .......................................................... 3-6 3.5 Water Loads, WA ............................................................................. 3-6 3.6 Wind Loads, WS ............................................................................... 3-7 3.7 Wind on Live Load, WL ...................................................................... 3-7 3.8 Earthquake Effects, EQ ..................................................................... 3-7 3.9 Ice Load, IC .................................................................................... 3-8 3.10 Earth Pressure, EV, EH, or ES ............................................................ 3-8 3.11 Temperature, Shrinkage, Creep, Settlement, TU, SH, CR, SE ................. 3-8 MAY 2009 LRFD BRIDGE DESIGN iv 3.11.1 Temperature Effects ................................................................ 3-8 3.11.2 Shrinkage Effects .................................................................. 3-11 3.12 Pile Downdrag, DD ......................................................................... 3-11 3.13 Friction Forces, FR .......................................................................... 3-11 3.13.1 Sliding Bearings .................................................................... 3-11 3.13.2 Soil/Backwall Interface and Soil/Footing Interface ..................... 3-11 3.14 Extreme Event ............................................................................... 3-12 3.14.1 Vehicle Collision, CT .............................................................. 3-12 3.14.2 Vessel Collision, CV ............................................................... 3-12 3.15 Uplift ............................................................................................ 3-12 3.15.1 Deck Pours ........................................................................... 3-13 3.16 Construction Loads ......................................................................... 3-13 3.17 Deflections .................................................................................... 3-13 4. STRUCTURAL ANALYSIS AND EVALUATION ........................................... 4-1 4.1 Computer Programs ......................................................................... 4-1 4.2 Load Distribution .............................................................................. 4-2 4.2.1 Dead Load Distribution ............................................................ 4-2 4.2.2 Live Load Distribution .............................................................. 4-2 4.2.2.1 Steel and Prestressed Concrete Beams .................................. 4-3 4.2.2.2 Slab Spans and Timber Decks .............................................. 4-3 4.2.3 Sidewalk Pedestrian Live Load .................................................. 4-3 4.3 Load Rating ..................................................................................... 4-4 4.4 Substructure Fixity ........................................................................... 4-5 4.5 Structural Models ............................................................................. 4-5 4.6 LRFD Exceptions .............................................................................. 4-5 4.6.1 Pedestrian Bridges .................................................................. 4-6 4.6.2 Rehabilitation Projects ............................................................. 4-6 4.6.3 Railroad Bridges and Bridges or Structures near Railroads ............ 4-6 5. CONCRETE STRUCTURES ....................................................................... 5-1 5.1 Materials ......................................................................................... 5-1 5.1.1 Concrete ................................................................................ 5-1 OCTOBER 2009 LRFD BRIDGE DESIGN v 5.1.2 Reinforcing Steel ..................................................................... 5-4 5.1.3 Reinforcement Bar Couplers ..................................................... 5-4 5.1.4 Prestressing Steel ................................................................... 5-4 5.1.5 Post-tensioning Hardware ........................................................ 5-5 5.2 Reinforcement Details ....................................................................... 5-5 5.2.1 Minimum Clear Cover and Clear Spacing .................................... 5-5 5.2.2 Reinforcing Bar Lists ................................................................ 5-7 5.2.3 General Reinforcement Practices ............................................. 5-14 5.2.4 Reinforcement Bar Couplers ................................................... 5-14 5.2.5 Adhesive Anchors .................................................................. 5-14 5.2.6 Shrinkage and Temperature Reinforcement .............................. 5-15 5.3 Concrete Slabs............................................................................... 5-15 5.3.1 Geometry ............................................................................. 5-15 5.3.2 Design/Analysis .................................................................... 5-16 5.3.3 Exterior Strip ........................................................................ 5-17 5.3.4 Reinforcement Layout ............................................................ 5-17 5.3.5 Camber and Deflections ......................................................... 5-19 5.4 Pretensioned Concrete .................................................................... 5-20 5.4.1 Geometry ............................................................................. 5-20 5.4.2 Stress Limits ........................................................................ 5-23 5.4.3 Design/Analysis .................................................................... 5-23 5.4.4 Detailing/Reinforcement ........................................................ 5-26 5.4.5 Camber and Deflection .......................................................... 5-26 5.4.6 Standard I-Beams ................................................................. 5-27 5.4.7 Rectangular Beams ............................................................... 5-27 5.4.8 Double-Tee Beams ................................................................ 5-30 5.5 Post-Tensioned Concrete ................................................................. 5-30 5.5.1 PT Slab Bridges..................................................................... 5-30 5.5.2 PT I-Girders ......................................................................... 5-30 5.5.3 PT Precast or Cast-In-Place Box Girders ................................... 5-30 5.6 Concrete Finishes and Coatings ........................................................ 5-32 5.7 Design Examples ............................................................................ 5-32 5.7.1 Three-Span Haunched Reinforced Concrete Slab ....................... 5-33 OCTOBER 2009 LRFD BRIDGE DESIGN vi 5.7.2 Prestressed I-Beam Design Example ....................................... 5-65 5.7.3 Three-Span Haunched Post-Tensioned Concrete Slab Design Example .................................................................... 5-97 6. STEEL STRUCTURES ............................................................................... 6-1 6.1 Materials ......................................................................................... 6-1 6.2 General Dimensions And Details ......................................................... 6-4 6.3 General Design Philosophy ................................................................ 6-7 6.3.1 Shear Connectors .................................................................... 6-8 6.3.2 Fatigue .................................................................................. 6-8 6.3.3 Deflections ............................................................................. 6-9 6.3.4 Camber ............................................................................... 6-10 6.4 Rolled Beams ................................................................................. 6-13 6.5 Plate Girders ................................................................................. 6-13 6.5.1 High Performance Steel Girders .............................................. 6-14 6.6 Horizontally Curved Steel Girders ..................................................... 6-14 6.7 Box Or Tub Girders ......................................................................... 6-17 6.8 Bolted Connections And Splices ........................................................ 6-18 6.9 Two-Span Plate Girder Design Example ............................................. 6-19 APPENDIX 6-A ...................................................................................... 6-117 7. RESERVED 8. WOOD STRUCTURES .............................................................................. 8-1 8.1 Materials ......................................................................................... 8-1 8.1.1 Wood Products ....................................................................... 8-1 8.1.2 Fasteners And Hardware .......................................................... 8-2 8.1.3 Wood Preservatives ................................................................. 8-2 8.2 Timber Bridge Decks ........................................................................ 8-3 8.2.1 General ................................................................................. 8-3 8.2.2 Geometry ............................................................................... 8-5 8.2.3 Design/Analysis ...................................................................... 8-5 8.2.4 Detailing ................................................................................ 8-6 MARCH 2010 LRFD BRIDGE DESIGN vii 8.2.5 Camber/Deflections ................................................................. 8-6 8.3 Timber Pile Caps .............................................................................. 8-6 8.3.1 Geometry ............................................................................... 8-7 8.3.2 Design/Analysis ...................................................................... 8-7 8.3.3 Detailing ................................................................................ 8-7 8.3.4 Camber/Deflections ................................................................. 8-7 8.4 Additional References ....................................................................... 8-7 8.5 Design Examples .............................................................................. 8-8 8.5.1 Longitudinally Laminated Timber Deck Design Example ............... 8-8 8.5.2 Design Example: Timber Pile Cap ............................................ 8-26 9. DECKS AND DECK SYSTEMS ................................................................... 9-1 9.1 General ........................................................................................... 9-1 9.1.1 Deck Drainage ........................................................................ 9-2 9.2 Concrete Deck on Beams .................................................................. 9-2 9.2.1 Deck Design and Detailing........................................................ 9-4 9.3 Reinforced Concrete Deck Design Example ........................................ 9-19 10. FOUNDATIONS .................................................................................... 10-1 10.1 Determination of Foundation Type and Capacity ................................. 10-1 10.1.1 Foundation Report ................................................................. 10-1 10.1.2 Foundation Recommendations ................................................ 10-1 10.2 Piles ............................................................................................. 10-3 10.3 Drilled Shafts ................................................................................. 10-7 10.4 Footings ...................................................................................... 10-10 10.4.1 General ............................................................................. 10-10 10.4.2 Footings Supported on Piling or Drilled Shafts ......................... 10-11 10.4.3 Spread Footings .................................................................. 10-15 10.5 Pile Bent Piers and Integral Abutments ........................................... 10-15 10.6 Evaluation of Existing Pile Foundations when Exposed by Scour ......... 10-16 10.7 Structure Excavation and Backfill ................................................... 10-17 JUNE 2010 LRFD BRIDGE DESIGN viii Appendix 10-A: Sample Bridge Construction Unit Recommendations .......... 10-19 11. ABUTMENTS, PIERS, AND WALLS ....................................................... 11-1 11.1 Abutments .................................................................................... 11-1 11.1.1 Integral Abutments ............................................................ 11-3.1 11.1.2 Semi-Integral Abutments .................................................... 11-6.2 11.1.3 Parapet Abutments ................................................................ 11-7 11.1.3.1 Low Abutments ................................................................ 11-9 11.1.3.2 High Abutments ............................................................... 11-9 11.1.4 Wingwalls .......................................................................... 11-12 11.1.5 Approach Panels ................................................................. 11-20 11.2 Piers ........................................................................................... 11-21 11.2.1 Geometrics ......................................................................... 11-21 11.2.2 Columns ............................................................................ 11-21 11.2.3 Cap ................................................................................... 11-21 11.2.4 Crash Walls ........................................................................ 11-22 11.2.5 Design and Reinforcement ................................................... 11-23 11.2.6 Miscellaneous ..................................................................... 11-24 11.2.6.1 Pile Bent ........................................................................ 11-25 11.3 Retaining Walls ............................................................................ 11-25 11.3.1 Cantilever Retaining Walls .................................................... 11-25 11.3.2 Counterfort Retaining Walls .................................................. 11-25 11.3.3 Anchored Walls ................................................................... 11-26 11.3.4 Mechanically Stabilized Earth Walls ....................................... 11-26 11.3.5 Prefabricated Modular Walls ................................................. 11-28 11.3.6 Timber Noise Walls on Retaining Walls ................................... 11-28 11.3.7 Cantilevered Sheet Pile Walls ................................................ 11-28 11.3.8 Design Charts of Cantilevered Sheet Pile Soil Retention Walls for Temporary Applications .......................................... 11-29 11.4 Design Examples .......................................................................... 11-39 11.4.1 High Parapet Abutment Design Example ................................ 11-39 11.4.2 Retaining Wall Design Example ............................................. 11-71 11.4.3 Three-Column Pier Design Example ....................................... 11-93 AUGUST 2006 LRFD BRIDGE DESIGN ix 12. BURIED STRUCTURES .......................................................................... 12-1 12.1 Geotechnical Properties ................................................................... 12-1 12.2 Box Culverts .................................................................................. 12-2 12.2.1 Precast ................................................................................ 12-2 12.2.2 Cast-In-Place........................................................................ 12-4 12.3 Design Guidance ............................................................................ 12-4 12.4 Arch Or 3-Sided Structure Design Data ............................................. 12-6 12.5 Design Criteria for Long-Span Corrugated Steel Structures ................ 12-14 12.6 10' x 10' Precast Concrete Box Culvert Design Example .................... 12-18 13. RAILINGS ........................................................................................... 13-1 13.1 Materials ....................................................................................... 13-1 13.2 Design Requirements ...................................................................... 13-1 13.2.1 Traffic Railing ...................................................................... 13-9 13.2.2 Pedestrian/Bicycle Railing .................................................... 13-11 13.2.3 Combination Railing ............................................................ 13-11 13.2.4 Strength of Standard Concrete Barriers ................................. 13-12 13.2.5 Protective Screening ............................................................ 13-15 13.2.6 Architectural/Ornamental Railings ......................................... 13-15 13.3 Design Examples .......................................................................... 13-16 13.3.1 Type F Barrier Design Example ............................................ 13-17 13.3.2 Adhesive Anchor Design Example .......................................... 13-31 14. JOINTS AND BEARINGS ...................................................................... 14-1 14.1 Bridge Movements and Fixity ........................................................... 14-1 14.2 Expansion Joints ........................................................................... 14-1 14.2.1 Thermal Movements .............................................................. 14-2 14.2.2 Strip Seal Expansion Joints ..................................................... 14-2 14.2.3 Modular Expansion Joints ....................................................... 14-3 14.2.4 Expansion Joint Detailing ....................................................... 14-3 14.3 Bearings ....................................................................................... 14-4 14.3.1 Loads and Movements ........................................................... 14-5 14.3.2 Bearing Details ..................................................................... 14-5 APRIL 2009 LRFD BRIDGE DESIGN x 14.3.3 Elastomeric Bearings ............................................................. 14-6 14.3.3.1 Design ............................................................................ 14-6 14.3.3.1.1 Size and Stability ................................................ 14-7 14.3.3.2 Fixed Bearings ................................................................. 14-7 14.3.3.3 Expansion Bearings .......................................................... 14-8 14.3.3.3.1 Minimum Compressive Load ................................. 14-8 14.3.4 Pot Bearings ......................................................................... 14-9 14.3.5 Other Types of Bearings ...................................................... 14-10 14.4 Curved Plate Design ..................................................................... 14-10 14.5 Bearing Plate Design .................................................................... 14-11 14.6 Sole Plate Design (Steel Beams) .................................................... 14-12 14.7 Tables ........................................................................................ 14-12 14.8 Design Examples .......................................................................... 14-20 14.8.1 Fixed Elastomeric Bearing Design Example ............................. 14-21 14.8.2 Expansion Elastomeric Bearing Design Example ...................... 14-29 15. BRIDGE LOAD RATING ....................................................................... 15-1 15.1 General ....................................................................................... 15-1 15.2 Analysis ...................................................................................... 15-3 15.2.1 Computer Programs .............................................................. 15-3 15.2.2 Refined Analysis ................................................................... 15-3 15.3 Loads .......................................................................................... 15-4 15.4 Rating Equation Factors ................................................................. 15-6 15.5 Rating New Bridges ....................................................................... 15-6 15.6 Re-rating Existing Bridges .............................................................. 15-6 15.7 Substructures ............................................................................... 15-7 15.8 Non-Standard Bridge Types ........................................................... 15-8 15.9 Timber Bridges ............................................................................. 15-8 15.10 Culverts ....................................................................................... 15-9 15.11 Gusset Plates ............................................................................. 15-11 15.12 Load Testing .............................................................................. 15-11 15.13 Load Posting .............................................................................. 15-11 15.13.1 General ............................................................................. 15-11 APRIL 2009 LRFD BRIDGE DESIGN xi 15.13.2 Rating Factors for Posting .................................................... 15-14 15.14 Overweight Permits ..................................................................... 15-15 15.15 Physical Inspection Rating (PIR) ................................................... 15-16 15.16 Forms and Documentation ........................................................... 15-17 15.17 Submittal / Filing ........................................................................ 15-18 APPENDIX 15-A: GLOSSARY ................................................................. 15-20 APPENDIX 15-B: RATING FORMS .......................................................... 15-24 APPENDIX 15-C: OVERWEIGHT PERMIT RESTRICTIONS FOR BRIDGES ...... 15-25 APPENDIX 15-D: MINNESOTA LEGAL (POSTING) LOADS .......................... 15-26 APPENDIX 15-E: MINNESOTA STANDARD PERMIT TRUCKS G-80 .............. 15-27 APPENDIX 15-F: MINNESOTA STANDARD PERMIT TRUCKS G-07 ............... 15-28 A. MEMOS #2005-01 LRFD and Bridge Load Rating Issues ................... (dated February 14, 2005) #2005-02 Discontinue Use of Cast Bearing Option .............. (dated November 9, 2005) #2005-03 New MN45 and MN54 PCB ................................... (dated November 10, 2005) #2006-01 New MN63 PCB .............................................................. (dated May 31, 2006) #2007-01 Bridge Office Substructure Protection Policy .............. (dated July 23, 2007) #2007-02 Adhesive Anchors Under Sustained Tensile Loads ...... (dated Oct. 3, 2007) #2007-03 Prestressed Beam Camber and Deflection................... (dated Oct. 3, 2007) #2008-01 Prestressed Concrete Design Calculation of Prestress Losses and Beam Camber & Deflection ........................................ (dated Sept. 18, 2008) #2008-02 Truss Bridge Gusset Plate Analysis ............................. (dated Oct. 20, 2008) APRIL 2009 LRFD BRIDGE DESIGN xii [ This page intentionally left blank ] MARCH 2006 LRFD BRI DGE DESI GN 1- 1 This sect ion cont ains general informat ion about t he manual along wit h a general descript ion of t he Bridge Office and it s procedures. This manual cont ains Mn/ DOT Bridge Office policies and procedures for t he design, evaluat ion, and rehabilit at ion of bridges. Except where not ed, t he design provisions herein employ t he Load and Resist ance Fact or Design ( LRFD) met hodology set fort h by AASHTO. Mn/ DOT ut ilizes a decimal numbering syst em t o classify document s. The 5 before t he hyphen represent s a publicat ion relat ed t o engineering t his is a t est funct ions. The 300 series of document s is assigned t o t he Bridge Office; t he 90 series indicat es t hat t his is a Manual . The last digit 2 specifies t hat t he subj ect mat t er of t he document is Design . The original bridge design manual, numbered 5- 392, provided guidance for t he design of highway st ruct ures in Minnesot a in accordance wit h allowable st ress design met hods. Subsequent ly, it has received periodic updat es as design met hods have changed. This version of t he Bridge Design Manual cont ains significant changes. I t present s Mn/ DOTs design pract ices in conformance wit h a new design met hodology, Load and Resist ance Fact or Design ( LRFD) , and also cont ains fift een comprehensive design examples. Use of t his manual does not relieve t he design engineer of responsibilit y for t he design of a bridge or st ruct ural component . Alt hough Bridge Office policy is present ed here for numerous sit uat ions, cont ent of t he manual is not int ended t o be exhaust ive. Therefore, use of t his manual must be t empered wit h sound engineering j udgement . Aft er t he int roduct ory mat erial provided in t his sect ion, t he manual cont ains mat erial arranged around t he following sect ion headings. To simplify locat ing mat erial, sect ion numbers correspond t o t hose used in t he LRFD specificat ions: 1) I nt roduct ion 2) General Design and Locat ion Feat ures 3) Loads and Load Fact ors 4) St ruct ural Analysis and Evaluat ion 5) Concret e St ruct ures 6) St eel St ruct ures 7) Reserved 8) Wood St ruct ures 9) Decks and Deck Syst ems 10) Foundat ions 1. I NTRODUCTI ON 1.1 Over vi ew of Manual 5- 392 1.1.1 Mat er i al Cont ai ned i n Manual 5- 392 MARCH 2006 LRFD BRI DGE DESI GN 1- 2 11) Abut ment s, Piers, and Walls 12) Buried St ruct ures 13) Railings 14) Joint s and Bearings Memos This manual will be updat ed mult iple t imes each year as procedures are updat ed and new informat ion becomes available. Current files for each sect ion of t he manual are available on t he Bridge Office Web sit e at : ht t p: / / www. dot . st at e. mn. us/ bridge/ . Each sect ion of t he manual cont ains general informat ion at t he st art of t he sect ion. Design examples ( if appropriat e) are locat ed at t he end of each sect ion. The general cont ent is divided int o subsect ions t hat are ident ified wit h numerical sect ion labels in t he left margin. Labels for design example subsect ions are ident ified wit h alphanumeric labels in t he left hand margin. The left hand margin also cont ains references t o LRFD Design Specificat ion Art icles, Equat ions, and Tables. These references are enclosed in square bracket s. Wit hin t he body of t he t ext , references t o ot her sect ions of t his manual are direct ly cit ed ( e. g. Sect ion 10.1) . References t o t he LRFD Specificat ions wit hin t he main body of t he t ext cont ain a prefix of: LRFD. A bridge is defined under Minnesot a Rule 8810. 8000 as a st ruct ure having an opening measured horizont ally along t he cent er of t he roadway of t en feet or more bet ween undercopings of abut ment s, bet ween spring line of arches, or bet ween ext reme ends of openings for mult iple boxes. Bridge also includes mult iple pipes where t he clear dist ance bet ween openings is less t han half of t he smaller cont iguous opening. I n accordance wit h Minnesot a St at ut e 15. 06 Subd. 6, t he Commissioner of Transport at ion has delegat ed approval aut horit y for St at e Preliminary Bridge Plans, and St at e, Count y and Cit y Final Bridge Plans t o t he St at e Bridge Engineer. Plans for all bridge const ruct ion or reconst ruct ion proj ect s locat ed on t he Trunk Highway Syst em, and plans on Count y or Cit y highways funded fully or in part by st at e funds shall be approved by t he St at e Bridge Engineer. 1.1.2 Updat es t o Manual 5- 392 1.2 Gener al Br i dge I nf or mat i on 1.1.3 For mat of Manual Ref er ences MARCH 2006 LRFD BRI DGE DESI GN 1- 3 The Bridge Office is responsible for conduct ing all bridge and st ruct ural design act ivit ies and for providing direct ion, advice, and services for all bridge const ruct ion and maint enance act ivit ies. The responsibilit ies include: Providing overall administ rat ive and t echnical direct ion for t he office. Reviewing and approving all preliminary and final bridge plans prepared by t he office and consult ant s. Represent ing t he Depart ment in bridge design, const ruct ion and maint enance mat t ers wit h ot her agencies. The Office is under t he direct ion of t he St at e Bridge Engineer. I t is composed of sect ions and unit s as shown on t he organizat ional chart ( Figure 1. 2. 1. 1) . Each of t hese subdivisions wit h t heir principal funct ions is list ed as follows: 1) Bridge Design Sect ion Responsible for t he design, plans, and special provisions act ivit ies for bridges, and miscellaneous t ransport at ion st ruct ures. a) Design Unit i) Designs and draft s bridge plans. ii) Reviews bridge plans prepared by consult ing engineers. iii) Prepares special provisions for bridge plans. iv) Designs and draft s plans for miscellaneous highway st ruct ures. v) Provides t echnical assist ance, designs, and plans for special bridge and st ruct ural problems. b) Bridge St andards and Research Unit i) Provides design aids and st andards for t he office and for consult ant s, count ies, and cit ies. ii) Coordinat es t he development and users of comput er programs wit h dat a processing syst ems. iii) Support s comput er users t hroughout t he office and manages t he local area net work. iv) Provides oversight for research proj ect s, which involve t he Bridge Office. c) Design/ Build Unit i) Provides oversight of design/ build proj ect s. d) LRFD I mplement at ion i) Maint ains LRFD Bridge Design Manual. ii) Provides support t o office and consult ing engineers concerning LRFD issues. 2) Bridge Planning Sect ion Responsible for program, cost est imat es, preliminary bridge plan act ivit ies for Trunk Highways and review of st at e aid bridges. a) Bridge Agreement s and Est imat es Unit 1. 2. 1 Br i dge Of f i ce MARCH 2006 LRFD BRI DGE DESI GN 1- 4 i) Select s and negot iat es wit h consult ing engineers and administ ers engineering agreement s for t he preparat ion of bridge plans. ii) Provides liaison bet ween t he office and t he consult ing engineer ret ained t o prepare bridge plans. iii) Coordinat es public and privat e ut ilit y requirement s for bridges. iv) Prepares preliminary, comparat ive and final cost est imat es. v) Maint ains and provides current program and plan st at us records. b) Preliminary Plans i) Conduct s preliminary st udies from layout s and develops preliminary bridge plans. ii) Provides liaison wit h dist rict and cent ral office road design t hrough t he design st age. iii) Obt ains required permit s from ot her agencies for bridges. c) St at e Aid Bridge Unit i) Reviews bridge plans and special provisions for count y, t ownship, and municipal st at e aid proj ect s. ii) Provides t echnical assist ance t o count ies and municipalit ies, when request ed, for nonpart icipat ing proj ect s. 3) Bridge Const ruct ion and Maint enance Sect ion Responsible for bridge const ruct ion and maint enance specificat ions, and bridge const ruct ion and maint enance advisory service act ivit ies t o t he office and t o t he j ob sit e. a) Const ruct ion and Maint enance Unit ; Nort h, Met ro and Sout h Regions i) Provides const ruct ion and maint enance advisory service t o bridge const ruct ion and maint enance engineers in t he field. ii) Writ es bridge const ruct ion and maint enance specificat ions, manuals and bullet ins. iii) Writ es and maint ains t he file of current special provisions for bridge const ruct ion and maint enance. iv) Performs preliminary, periodic and final review of bridge const ruct ion and maint enance proj ect s and makes recommendat ions. v) Reviews bridge plans and special provisions prior t o let t ings and makes recommendat ions. vi) Aids municipal and count y engineers wit h bridge const ruct ion and maint enance problems, upon request . vii) Provides foundat ion design including select ion of pile t ype, lengt h, design load, and foundat ion preparat ion. viii) Reviews bridge improvement proj ect s and prepares recommendat ions for scope of work. JULY 2003 LRFD BRI DGE DESI GN 1- 5 b) Bridge Rat ings Unit i) Makes bridge rat ings and load post ings analysis for exist ing bridges and maint ains t he records. ii) Reviews and approves special load permit request s. c) St ruct ural Met als I nspect ion Unit i) Provides inspect ion services for st ruct ural met als, fabricat ion and assembly t o ensure conformit y wit h plans and specificat ions. d) Fabricat ion Met hods Unit i) Reviews and approves st ruct ural met als shop drawings submit t ed by fabricat ors. ii) Provides fabricat ion advisory service t o designers, fabricat ors and field const ruct ion and maint enance personnel. iii) Provides overhead sign design services t o t he Office of Traffic Engineering, including t he design of bridge- mount ed sign t russes. e) Bridge Management Unit i) Maint ains invent ory and inspect ion dat a for t he 19, 600 bridges in Minnesot a. Works wit h all agencies t o make cert ain appropriat e dat a is collect ed. ii) Responsible for implement ing bridge management syst ems t o provide informat ion on bridges for maint enance, repair, rehabilit at ion and replacement . f) Bridge I nspect ion Unit i) Provides expert assist ance t o t he Dist rict s in organizing and conduct ing inspect ions of complex bridges, special feat ures, and fract ure crit ical bridges. ii) Conduct s qualit y assurance inspect ions of all agencies responsible for bridge inspect ions in Minnesot a. iii) Reviews, recommends and provides bridge inspect ion t raining for Dist rict , count y, and municipal bridge inspect ors. 4) Hydraulic Engineering Sect ion Responsible for providing st at ewide hydraulic engineering services t hat include design, const ruct ion and maint enance act ivit ies. I n addit ion, t he sect ion provides leadership in t he development and implement at ion of hydraulic aut omat ion t echnology, est ablishes policy pert aining t o hydrology and hydraulics, prepares design aids, provides client t raining, part icipat es in research proj ect s, and represent s t he depart ment on st at e and nat ional commit t ees. a) Bridge Design Hydraulics Unit i) Provides bridge and culvert wat erway designs for t runk highway, count y, cit y and t ownship proj ect s. ii) Analyzes and evaluat es inplace bridges for scour. MARCH 2006 LRFD BRI DGE DESI GN 1- 6 iii) Provides t echnical assist ance t o count ies and municipalit ies upon request . iv) Provides t raining in hydrology and hydraulics. b) Road Design Hydraulics Unit i) Evaluat es and codes all bridges over wat er for scour. ii) Provides t echnical assist ance t o Dist rict s on all aspect s of drainage design. iii) Reviews and cost prorat es st orm drains on t he municipal and count y st at e aid syst em. iv) Coordinat es t he review of new product s and development of specificat ions and policies pert aining t o t heir use. c) Hydraulics Aut omat ion Unit i) Provides leadership and t echnical direct ion for managing t he st at ewide hydraulic aut omat ion effort . ii) Develops and implement s t he means t o int egrat e t he hydraulic design process wit h t he road design process. iii) Develops, implement s, and support s a hydraulic informat ion syst em t o facilit at e t he sharing of hydraulic dat a among all users and st akeholders. iv) Provides st at ewide t raining and support in t he implement at ion and use of hydraulic aut omat ion t echniques. For more informat ion, visit t he Bridge Office Web sit e at : ht t p: / / www. dot . st at e. mn. us/ bridge/ . MARCH 2006 LRFD BRI DGE DESI GN 1- 7 Fi gur e 1.2. 1. 1 Mn/ DOT Br i dge Of f i ce Or gani zat i on Char t JULY 2003 LRFD BRI DGE DESI GN 1- 8 Highways t hroughout t he nat ion are divided int o syst ems. These syst em designat ions are import ant t o know because design st andards can vary bet ween t he syst ems. The various highway syst ems are classified according t o t he Agency t hat has responsibilit y for t heir improvement , maint enance and t raffic regulat ion enforcement . List ed below are t he j urisdict ional divisions in Minnesot a: 1) Trunk Highway Syst em The Trunk Highway Syst em consist s of all highways, including t he I nt erst at e rout es, under t he j urisdict ion of t he St at e of Minnesot a. These rout es generally are t he most import ant in t he st at e, carry t he great est t raffic volumes, and operat e at t he highest speeds. 2) Count y Highway Syst em The Count y Highway Syst em is made up of t hose roads est ablished and designat ed under t he aut horit y of t he count y board. They generally are t he more import ant rout es wit hin a count y t hat are not on t he Trunk Highway Syst em. 3) Township Road Syst em The Township Road Syst em is made up of t he roads est ablished under t he aut horit y of t he t own board. They generally are of local import ance. 4) Municipal St reet Syst em The Municipal St reet Syst em is all roads wit hin a municipalit y not designat ed as a t runk highway or count y road. They are generally of local import ance. All publicly owned bridges eit her on or over a t runk highway and over 10 feet in lengt h measured along t he cent erline of t he highway are assigned a number for ident ificat ion and cost account ing purposes. The numbering scheme followed in assigning bridge numbers depends on t he t ime of const ruct ion. Wit h few except ions, t he numbering procedure is as follows: 1) Prior t o about 1950, all bridges were numbered consecut ively from 1 t o 9999 as t hey were const ruct ed. The 8000 series was used for culvert s over 10 feet in lengt h ( measured along t he cent erline of t he highway) . The 7000 series was reserved for count y bridges at t runk highway int ersect ions. Five- digit bridge numbers beginning wit h L or R designat e bridges in local bridge syst ems. 2) Since about 1950, a five- digit number has been assigned t o each bridge as it was const ruct ed. The first t wo digit s coincide wit h t he count y number ( 01- 87) in which t he bridge is locat ed ( 99 refers t o t emporary bridges) . The last t hree digit s are assigned consecut ively using t he following guidelines: 1. 2. 2 Hi ghw ay Sy st ems 1.2.3 Br i dge Number s APRI L 2008 LRFD BRI DGE DESI GN 1- 9 a. 001- 499 are used for regular t runk highway bridges. b. 500- 699 are used for count y bridges. c. 700- 999 are used for int erst at e bridges ( any bridge on or over t he int erst at e syst em) . 3) I n 1991, addit ional numbers were required for bridges on t he st at e aid syst em in Hennepin Count y and for int erst at e bridges in Hennepin Count y. To allocat e more numbers for bridges on t he local syst em an alpha charact er is used as t he t hird charact er of t he bridge number. For example, t he next bridge number aft er Bridge No. 27699 will be Bridge No. 27A00. Not e t hat t his happens only aft er 500 and 600 series have been exhaust ed. To allocat e more numbers on t he I nt erst at e road syst em, t he 400 series of numbers will be used along wit h t he 700, 800, 900' s present ly used. For a bridge number XXYZZ, t he following now applies: XX = Count y ident ificat ion number ( 99 = Temporary Bridge) Y = 0, 1, 2, 3, or R, T, U ( for Trunk Highway Bridges) Y = 4, 7, 8, 9, or V, or W ( for I nt erst at e Bridges) Y = X and Y ( Trunk Highway or I nt erst at e Culvert s) Y = 5 or 6 or A t hrough H ( for non- t runk highway Bridges) Y = J t hrough N, and P, Q ( for non- t runk highway Culvert s) ZZ = Sequence number ( 00 t hrough 99) As of Sept ember, 2006, t he following numbering scheme was added for: - Bridges or culvert s wit hout a highway over or under ( e. g. pedest rian t rail over st ream) - Exist ing bridges t hat have not been assigned a bridge number - Skyways and ot her miscellaneous st ruct ures such as conveyors, pipelines, or buildings Use t he format RZZZZ where: R = A lit eral charact er ZZZZ = Sequence number ( 0000 t hru 9999) 4) I n cases of t win bridges, a west bound or sout hbound lane bridge is generally assigned a lower number t han an east bound or nort hbound lane bridge. All bridge numbers are assigned by t he Bridge Office. A complet e list ing of all numbered bridges is available in comput er print out form ent it led Minnesot a Trunk Highway Bridge Log- St at ewide List ing . See Table 1. 2. 3.1 for a list ing of t he count y ident ificat ion numbers. MARCH 2006 LRFD BRI DGE DESI GN 1- 10 Tabl e 1.2.3.1 Mi nnesot a Count y I dent i f i cat i on Number s Count y No. Count y Name Di st r i ct Count y No. Count y Name Di st r i ct 01 Ait kin 1 & 3 45 Marshall 2 02 Anoka Met ro 46 Mart in 7 03 Becker 4 47 Meeker 8 04 Belt rami 2 48 Mille Lacs 3 05 Bent on 3 49 Morrison 3 06 Big St one 4 50 Mower 6 07 Blue Eart h 7 51 Murray 8 08 Brown 7 52 Nicollet 7 09 Carlt on 1 53 Nobles 7 10 Carver Met ro 54 Norman 2 11 Cass 2 & 3 55 Olmst ed 6 12 Chippewa 8 56 Ot t er Tail 4 13 Chisago Met ro 57 Penningt on 2 14 Clay 4 58 Pine 1 15 Clearwat er 2 59 Pipest one 8 16 Cook 1 60 Polk 2 17 Cot t onwood 7 61 Pope 4 18 Crow Wing 3 62 Ramsey Met ro 19 Dakot a Met ro 63 Red Lake 2 20 Dodge 6 64 Redwood 8 21 Douglas 4 65 Renville 8 22 Faribault 7 66 Rice 6 23 Fillmore 6 67 Rock 7 24 Freebor n 6 68 Roseau 2 25 Goodhue 6 69 St . Louis 1 26 Grant 4 70 Scot t Met ro 27 Hennepin Met ro 71 Sherbur ne 3 28 Houst on 6 72 Sibley 7 29 Hubbard 2 73 St earns 3 30 I sant i 3 74 St eele 6 31 I t asca 1, 2 & 3 75 St evens 4 32 Jackson 7 76 Swift 4 33 Kanabec 3 77 Todd 3 34 Kandiyohi 8 78 Traverse 4 35 Kit t son 2 79 Wabasha 6 36 Koochiching 1 & 2 80 Wadena 3 37 Lac Qui Parle 8 81 Waseca 7 38 Lake 1 82 Washingt on Met ro 39 Lake of t he Woods 2 83 Wat onwan 7 40 Le Sueur 7 84 Wilkin 4 41 Lincoln 8 85 Winona 6 42 Lyon 8 86 Wright 3 43 McLeod 8 87 Yellow Medicine 8 44 Mahnomen 2 MARCH 2006 LRFD BRI DGE DESI GN 1- 11 Bridge designs shall t ypically consider St rengt h, Service, Ext reme Event , and Fat igue limit st at es. The limit st at e checks will vary wit h t he component under considerat ion. Not all element s will require considerat ion of all limit st at es. For example, t he fat igue limit st at e need not be considered for fully prest ressed pret ensioned element s. This sect ion covers t he Bridge Office procedures for checking of bridge plans, scheduling of proj ect s, and revising or creat ing st andards. The general pract ice of most engineering offices is t o require t hat designs t hey produce be checked before t hey are reviewed and cert ified by t he Engineer in Responsible Charge . Alt hough t his pract ice has always been required for st ruct ures designed for Mn/ DOT, it is recognized t hat t he qualit y of t he checking process oft en varies according t o t ime rest raint s, confidence in t he designer, and t he inst ruct ions given t o t he checker. Therefore, in order t o maint ain a consist ent design checking process t he following guidance is given for rout ine bridge designs. For more complex or unusual designs, t he checker is advised t o discuss addit ional requirement s wit h t he design unit leader. Also, t he checking process described is not meant t o apply t o t he check or review funct ions required for Mn/ DOT review of consult ant plans ( see Sect ion 1. 3. 2.) or for const ruct ion false work reviews. ( See t he Bridge Const ruct ion Manual. ) Three t ypes of design checking will apply: 1) An independent analysis of t he complet ed design. 2) A check of original design comput at ions for mat hemat ical accuracy, applicat ion of code, and accept ed engineering pract ice. 3) A review of draft ed det ails for const ruct ibilit y and accept ed engineering pract ice. Generally, an independent analysis t o confirm t he adequacy of t he complet e design is preferred. Significant differences should be discussed and resolved before t he plan is cert ified. The separat e set of calculat ions should be included wit h t he design file as a record of t he complet ed design check. When circumst ances prevent a complet e independent analysis, as a minimum, an independent analysis shall be complet ed for t he following: 1) Live and dead loads 2) Crit ical beam lines 3) A pier cap 1.3 Pr ocedur es 1.3.1 Check i ng of Mn/ DOT Pr epar ed Br i dge Pl ans 1.2.4 Li mi t St at es t o Consi der i n Desi gn JULY 2003 LRFD BRI DGE DESI GN 1- 12 4) A pier foot ing 5) Main reinforcement for high abut ment s 6) An abut ment foot ing However, for t he element s not independent ly analyzed, t he original comput at ions should be checked for mat hemat ical accuracy of original design comput at ions, applicat ions of code, and accept ed engineering pract ice. Checked comput at ions should be init ialed by t he checker, and t he independent analysis should be included in t he design file. When doing a separat e analysis, t he checker may make simplifying assumpt ions t o st reamline t he checking process. However, when maj or differences are found, result s must be discussed and resolved wit h t he designer. For inst ance, for normal piers, piling might be analyzed for dead and live loads only if lat eral loads appear t o have been reasonably applied in t he original comput at ions or t he AI SC Beam Diagram and Formula Tables may be used t o approximat e pier cap moment and shear. Whet her t he check is a complet ely independent analysis or a minimal analysis combined wit h a comput at ions check, some det ails, such as t he reinforcing det ails in a wall corner, also require review by t he checker. Oft en referencing old bridge plans wit h similar det ails allows t he checker t o compare t he current design t o det ails t hat have performed well in t he past . Consult ant prepared bridge plans are creat ed by privat e engineering firms t hrough cont ract s wit h t he Depart ment . The finished plans are complet e t o t he ext ent t hat t hey can be used for const ruct ion. Since t hese plans receive final approval of t he St at e Bridge Engineer, t here must be assurance t hat t he plans are geomet rically accurat e and buildable; st ruct ural design is adequat e and design codes have been correct ly applied; proper direct ion is given t o t he const ruct ion cont ract or; and all const ruct ion cost s are account ed for. Plan errors may cause cost ly const ruct ion delays or safet y may be compromised by an inadequat e design. To keep consult ant plan reviews consist ent and t imely, a procedure was developed as a guide t hat assigns priorit y t o specific it ems in t he plans. The overall review includes a Thorough Check and Cursory Review of various it ems. The dist inct ion bet ween Thorough Check and Cursory Review is as follows: 1.3.2 Check i ng of Consul t ant Pr epar ed Br i dge Pl ans JULY 2003 LRFD BRI DGE DESI GN 1- 13 Thorough Check refers t o performing complet e mat hemat ical comput at ions in order t o ident ify discrepancies in t he plans, or conduct ing careful comparisons of known dat a and st andards of t he Proj ect wit h values given in t he plan. Cursory Review refers t o a comparat ive analysis for agreement wit h st andard pract ice and consist ency wit h similar st ruct ures, all wit h applicat ion of engineering j udgment . Mat hemat ical analysis is not required, but may be deemed necessary t o ident ify t he ext ent of a discrepancy. The review procedure is list ed on t he CONSULTANT BRI DGE PLAN REVI EW form following t his sect ion. Headings on t his list are defined as follows: PARTI AL PLAN: I n order t o assure t hat t he consult ant is proceeding in t he right direct ion, an early submit t al of t he plan is required. This submit t al usually consist s of t he General Plan and Elevat ion sheet showing t he overall geomet ry of t he st ruct ure and t he proposed beam t ype and spacing; t he Bridge Layout Sheet ; t he Framing Plan sheet ; and t he Bridge Survey sheet s. Errors and inconsist encies found in t his phase can be correct ed before t he ent ire plan is complet ed. For example, a framing plan, including t he proposed beams, must be assured as workable on t he part ial plan before t he consult ant get s deep int o t he design of t he remainder of t he bridge. FI NAL PLAN: A final plan should be complet e in all areas t o t he ext ent t hat it can be cert ified by t he designer, alt hough a cert ificat ion signat ure is not required for t his phase. THOROUGH CHECK: I t ems indicat ed for checking on t he consult ant s part ial plan must be correct . Given geomet ry must fit t he roadway layout . Most of t his informat ion can be checked using dat a from t he approved preliminary plan. Approval of t he part ial plan will indicat e t hat Mn/ DOT is sat isfied wit h t he geomet ry and proposed st ruct ure, and t he consult ant may proceed wit h furt her development of t he plan. For t he final plan, obvious draft ing and numerical errors should be marked t o point out t he errors t o t he consult ant , however, t he reviewer should not provide correct ions t o errors in t he consult ant s numerical comput at ions. Checking on t he final plan should be t horough t o eliminat e possible errors t hat may occur, such as t he pay it ems in t he Schedule of Quant it ies. Plan not es and pay it ems can be difficult for a consult ant t o ant icipat e because of frequent changes by Mn/ DOT. Pay it ems must be correct APRI L 2008 LRFD BRI DGE DESI GN 1- 14 because t hese are carried t hroughout t he ent ire account ing syst em for t he Proj ect . Plan ( P) quant it ies must also be correct ly indicat ed. CURSORY REVI EW: Normally, a cursory review would not require numerical calculat ions. This t ype of review can be conduct ed by reading and observing t he cont ent s of t he plan in order t o assure t he complet eness of t he work. The reviewer should be observant t o recognize what looks right and what doesnt look right . Obvious errors or inconsist encies on any part s of t he plan should be marked for correct ion. Alt hough st ruct ural design is usually t he maj or focus of any plan, most consult ant s are well versed in design procedures and should need only minimal assist ance from our office. A comparison of t he consult ant s calculat ions wit h t he plan det ails should be performed t o assure t hat t he plans reflect t heir design and t hat t he applicable codes are followed. An independent design by our office is t ime consuming and is not recommended unless t here is a reasonable doubt as t o t he adequacy of t he consult ant s design. NO REVI EW: A t horough review of t hese it ems would be t ime- consuming and may not produce correct ions t hat are vit al t o const ruct ion; t herefore, it is recommended t hat lit t le or no t ime be spent on t he list ed it ems. Numerous errors can occur in t he Bills of Reinforcement and quant it y values. However, checking t his informat ion is also t ime- consuming, hence t he burden of providing correct dat a should be placed on t he consult ant . Maj or Br i dges For maj or bridges designed by consult ant s, Mn/ DOT will require an independent peer review of t he design by a second design firm. Maj or bridges are generally defined as bridges cont aining spans 250 feet and great er in lengt h. Addit ionally, t he Bridge Design Engineer may elect t o require a peer review for unique bridge t ypes. Peer review requirement s will be described in t he Request for Proposal for consult ant s. An except ion t o t his requirement is st eel plat e girder bridges, where review will cont inue t o be performed by in- house design unit s. See t he Bridge Design Engineer for consult at ion on t hese requirement s. JULY 2003 LRFD BRI DGE DESI GN 1- 15 CONSULTANT BRI DGE PLAN REVI EW Br. No. ________ RTE ____ DATE: PARTI AL PLAN REC' D. _____ DATE FI NAL PLAN REC' D. ______ DESI GN GROUP _______________________ CONSULTANT ______________________________ No. OF SHEETS I N PLAN ______ DESCRI BE COMPLEXI TY_________________________________ EST. REVI EW TI ME BY DESI GN GROUP ________( hrs. ) ACTUAL REVI EW TI ME __________( hrs) PARTI AL PLAN FI NAL PLAN THOROUGH CHECK THOROUGH CHECK Horizont al and vert ical clearances Pay it ems and plan quant it ies St at ions and elevat ions on survey line Proj ect numbers Deck and seat elevat ions at working point s Design dat a block & Rat ing on GP&E sheet Deck cross- sect ion dimensions Job number Working line locat ion and dat a Cert ificat ion block Coordinat es at working point s and key st at ions St andard plan not es Subst ruct ur e locat ions by st at ion Concret e mix numbers Framing Plan Const r uct ion j oint locat ions Conformance t o preliminary plan Prest ressed beam design if inadequat e design is suspect ed Design loads Bridge seat elevat ions at wor king point s Ut ilit ies on bridge Exist ing maj or ut ilit ies near br idge CURSORY REVI EW St eel beam splice locat ions and diaphragm spacing; flange plat e t hickness incr ement s ( enough t o save 800+ # of st eel) Abut ment and Pier design t o be checked against consult ant s calculat ions Conformance t o foundat ion r ecommendat ions. Pile loads and eart h pr essures. Check against consult ant s calculat ions. CURSORY REVI EW Rebar series increment s ( min. 3") Proposed precast beams [ per 5- 393.509( 2) ] I nt er ior beam seat elevat ions Precast confor mance t o indust ry st andards Bot t om- of- foot ing elevat ions ( for adequat e cover) Proposed st eel beam sect ions Railing lengt hs and met al post spacing ( check for fit ) Use of B- det ails and st andard plan sheet s Conformance t o aest het ic requirement s Not es Gener al, const ruct ion, refer ence, et c. Quant it y it ems on t abulat ions Precast beam design ( Check against consult ant s calculat ions) NO CHECK OR REVI EW REQUI RED Diagonals on Layout sheet Figures in Bills of Reinforcement Bar shapes and dimensions Rebar placement dimensions Bar marks on det ails against list ed bars Quant it y values ( including t ot al of t abulat ions) JULY 2003 LRFD BRI DGE DESI GN 1- 16 To meet t he Depart ment s schedule requirement s for const ruct ion let t ings, t he following schedule for processing bridge plans, special provisions and est imat es must be followed. This schedule applies t o all proj ect s: Federal Aid, St at e Funds and Maint enance. I n general, processing of bridge plans, special provisions and est imat es for let t ings shall be given priorit y over all ot her work, and every effort must be made t o complet e t he processing in advance of t he t imes shown, which are deadlines. Deadl i ne Ti me Bef or e Let t i ng Dat e Schedul e and Remar k s Feder al Pr oj ect St at e Pr oj ect Bridge plans complet e t o t he ext ent t hat processing can be complet ed on schedule. 14 Weeks ( Fr iday) 12 Weeks ( Fr iday) Preliminary bridge pay it ems and quant it ies for est imat e ( t o Est imat ing Unit Design Services) 13 Weeks ( Fr iday) 11 Weeks ( Fr iday) Bridge plan and special provisions review complet e ( by Bridge Const r uct ion Unit ) 13 Weeks ( Fr iday) 11 Weeks ( Fr iday) Bridge special provisions complet e, ot her informat ion or mat erial for inclusion in Roadway Special Provisions complet e ( t o Special Provisions & Final Processing Unit Design Services) 12 Weeks ( Fr iday) 10 Weeks ( Fr iday) Bridge plans complet e, approved and dat ed ( t o Office Management Unit ) 12 Weeks ( Fr iday) 10 Weeks ( Fr iday) Final br idge pay it ems and quant it ies for est imat e ( t o est imat ing Unit Design Services) 12 Weeks ( Fr iday) 10 Weeks ( Fr iday) Final comput er runs for bridge est imat e during 9t h week during 8t h week Office copy and final br idge plans ( Br idge plans t o Special & Final Processing Unit Design Services for submit t al t o FHWA) 81/2 weeks ( Tuesday) 7 weeks ( Fr iday) Federal Proj ect t o FHWA 71/2 weeks ( Tuesday) 7 weeks ( Fr iday) Preliminary advert isement 61/2 weeks ( Tuesday) 6 weeks ( Fr iday) Final advert isement 51/2 weeks ( Tuesday) 5 weeks ( Friday) Sale of plans and proposals 5 weeks ( Friday) 5 weeks ( Friday) Last dat e for mailing let t er addendums by Special Provisions & Final Processing Unit Design Services 10 days ( Wednesday) 10 days ( Wednesday) 1.3.3 Schedul e f or Pr ocessi ng Const r uct i on Let t i ngs MARCH 2006 LRFD BRI DGE DESI GN 1- 17 Complet ing a bridge design proj ect for cont ract let t ing is a mult iple st ep process t hat involves input from a variet y of work unit s and personnel. Proj ect s are t racked by Mn/ DOT using t he Program and Proj ect Management Syst em ( PPMS) . Wit hin PPMS, proj ect s are divided int o act ivit ies and t he act ivit ies are furt her divided int o work t asks. For example, Act ivit y 1260 is Preliminary St ruct ure Plans and Work Task 2 of Act ivit y 1260 is Draft Preliminary Bridge Plan . Progress of t he work t asks on act ive bridge proj ect s is updat ed mont hly. Following are t ables t hat list work t asks for t he maj or bridge act ivit ies wit hin PPMS. Table 1. 3. 4. 1 cont ains a list ing of t he PPMS work t asks for Act ivit y 1260, Preliminary St ruct ure Plans . Tables 1. 3. 4. 2 and 1. 3. 4. 3 cont ain list ings of t he PPMS work t asks for Act ivit y 1270, Final St ruct ure Plans . For more informat ion on act ivit ies and work t asks wit hin PPMS, refer t o t he PPMS Act ivit y Manual locat ed on t he Mn/ DOT int ernal web sit e at ht t p: / / ihub.ot s/ proj dev/ pmu/ ppms/ . Tabl e 1.3.4. 1 PPMS Wor k Task s f or Mn/ DOT or Consul t ant Pr epar ed Pr el i mi nar y Br i dge Pl ans ( Act i vi t y 1260) Number Wor k Task Per cent of Act i vi t y Compl et ed 1 Receive and r eview informat ion ( grades, alignment , surveys, layout , Hydraulics report , Proj ect Design Memo. , Environment al repor t ) 15% 2 Draft Pr eliminary Bridge Plan 60% 3 Check Preliminary Bridge Plan 75% 4 Prepare Aest het ics Recommendat ion 80% 5 Receive and Plot Borings 85% 6 Receive Foundat ion Recommendat ions from Regional Br idge Const ruct ion Engineer 88% 7 Obt ain St at e Bridge Engineers Signat ur e 90% 8 Dist r ibut e Signed Plans & Dist ribut e responses on need for Signs, Light ing, TMC 91% 9 Preliminary Est imat e and Dist rict Let t er 95% 10 Obt ain FHWA Approval 99% 11 Turn over and meet wit h final Design 100% 1.3.4 Br i dge Pr oj ect Tr ack i ng Sy st em MARCH 2006 LRFD BRI DGE DESI GN 1- 18 Tabl e 1.3.4. 2 PPMS Wor k Task s f or Mn/ DOT Pr epar ed Fi nal Br i dge Pl ans ( Act i vi t y 1270) Number Wor k Task Per cent of Act i vi t y Compl et ed * 1 Receive Pr eliminary Bridge Plan, Final Repair Recommendat ion, or Special St ruct ur e Request 5% Receive Dist r ict Design I nfor mat ion ( Signal, Light ing, Signing, TMS, et c. ) Receive Ut ilit y I nformat ion 2 Receive St age Const r uct ion Sheet s 10% 3 Est ablish Geomet rics 20% 4 Conduct Analysis and Design, I ncluding Check 45% Draft and Check Plan Sheet s 5 I ncorporat e St andard Det ail Sheet s 75% 6 Const r uct ion Unit Review 80% 7 Figure Quant it ies 85% 8 Send I nfor mat ional Copies t o FHWA and Dist rict 88% 9 Final Check of Plan Set by Unit Leader 90% 10 Frame Special Provisions 95% 11 Final Revisions and Check of Plan Set 99% 12 Obt ain St at e Bridge Engineers Signat ur e 100% * May vary by j ob complexit y. Tabl e 1.3.4. 3 PPMS Wor k Task s f or Consul t ant Pr epar ed Fi nal Br i dge Pl ans ( Act i vi t y 1270) Number Wor k Task Per cent of Act i vi t y Compl et ed 1 Consult ant kick- off meet ing 25% 2 Part ial Plan Delivery and Review 45% 3 Final Plan Delivery and Review 85% 4 Submit for Signat ur e 100% MARCH 2006 LRFD BRI DGE DESI GN 1- 19 A list ing of t he work t ype codes used in PPMS is given in Table 1. 3. 4. 4. Tabl e 1.3.4. 4 PPMS Br i dge Wor k Ty pe Codes Wor k Ty pe Descr i pt i on 01 New Bridge 1A New Bridge ( Phase 1) ( Ear ly St eel or St age Const r uct ion) 1B New Bridge ( Phase 2) 02 Culver t 2X Culver t Ext ension 2B Concret e Ar ch 03 Temporary Br idge 04 Pedest r ian Bridge 05 Renovat ion 06 Widen w/ Subst ruct ure Work 6A Widen w/ Subst ruct ure Work ( Phase 1) ( Early St eel or St age 6B Widen wit h Subst ruct ure Wor k ( Phase 2) 6T Temporary Widening 07 Widen wit hout Subst ruct ur e Work 08 Bridge Lengt h/ Short 09 Replace Deck 10 Deck Overlay 11 Replace Railing or Median Bar rier 12 Bridge Paint ing 13 Subst ruct ur e Repair 14 Remove Br idge 15 Miscellaneous 16 Raise Bridge 17 Replace Super st ruct ure - No Preliminary Plan Req' d 18 Repair Railing or Median Barr ier 19 Replace Joint s 23 Widen wit hout Subst ruct ur e Work & Replace Deck 24 Widen wit hout Subst ruct ur e Work & Deck Overlay 25 Widen wit hout Subst ruct ur e Work, Deck Overlay & Paint 26 Widen wit hout Subst ruct ur e Work & Ot her Minor Work 27 Widen wit hout Subst ruct ur e Work & Paint 28 Replace Deck & Paint 29 Replace Deck & Ot her Minor Work 31 Deck Overlay & Replace Railing or Median Barrier 32 Deck Overlay, Replace Railing or Median Bar rier & Paint 33 Deck Overlay & Ot her Minor Work MARCH 2006 LRFD BRI DGE DESI GN 1- 20 Tabl e 1.3.4. 4 PPMS Br i dge Wor k Ty pe Codes ( Cont i nued) Wor k Ty pe Descr i pt i on 35 Deck Overlay & Paint 37 Replace Railing or Median Bar rier & Paint 38 Replace Railing or Median Bar rier & Ot her Minor Work 39 Paint & Ot her Minor Work 40 Repair Railing or Median Barr ier & Replace Joint s 41 Widen wit hout Subst ruct ur e Work, Replace Deck & Paint 42 Replace Railing or Median Bar rier & Replace Joint s 44 Deck Repair & Replace Joint s 45 Deck Overlay & Repair Railing or Median Barrier 46 Deck Overlay, Repair Railing or Median Barr ier & Replace Joint s 47 Deck Repair - Rail Rehab 48 Minor Work ( Deck Repair, Paint , & Repair Railing or Median Barrier) 49 Deck Overlay, Paint & Repair Railing or Median Barrier 50 Ret aining Wall 51 Parking Garage 52 Repair Concr et e Arch 54 Riprap 58 Paint & Replace Joint s 60 Widen wit h Subst ruct ure Wor k & Replace Deck 61 Widen wit h Subst ruct ure Wor k & Deck Over lay 62 Widen wit h Subst ruct ure Wor k, Deck Overlay & Paint 63 Widen wit h Subst ruct ure Wor k & Paint 64 Widen wit h Subst ruct ure Wor k, Replace Deck & Paint 66 Widen wit h Subst ruct ure Wor k & Replace Superst r uct ure 68 Widen wit h Subst ruct ure Wor k & Replace Railing or Median Barrier 69 Miscellaneous Maj or 71 Deck Overlay & Replace Joint s 91 Probably Br idge 92 Probably Culvert 98 Bridge Scoping 99 Bridge St udy MARCH 2006 LRFD BRI DGE DESI GN 1- 21 1.3.5 Appr oval Pr ocess f or St andar ds FLOW CHARTFORREVISING BRIDGESTANDARDS(Includes B-Details and Standards)Request For New Standards Or Revising Existing StandardsBridge Standards UnitReview By SSRCReview By R& DMinorModificationTo ExistingStandardsModificationsNeeded?Does RevisionAffect Others Outside Of BridgeOffice?NoNoYesYesYesNoMakeChangeShow NewRevisionDateYellowRoutingProcessNew Standard Created,Existing Standards RevisedStandard Signed ByState Bridge EngineerTransmittal MemoTo Manual UsersPublish On Web SiteSolicit/Receive CommentsInput from:R& D Comm.SSRC CommOther Bridge Office Engr./StaffOther Mn/DOTPersonnelConsultantsIndustryCities/CountiesFHWABR3810.CDR FEBRUARY 2007 LRFD BRI DGE DESI GN 2- 1 2. GENERAL DESI GN AND LOCATI ON FEATURES 2.1 Geomet r i cs 2.1.1 Br i dge Geomet r i cs The design of a bridge t ypically t akes place in t wo maj or phases of work: preliminary design and final design. During preliminary design, t he st ruct ure t ype, t he foundat ion t ype, t he aest het ics, and t he primary geomet ry for t he bridge are det ermined. During final design, specific det ails for all of t he element s of t he bridge are developed and present ed in t he plan set . These det ails include mat erial descript ions, quant it ies, and geomet ric informat ion. Final plan set s are t ypically assembled in an order t hat roughly follows t he order of const ruct ion: from t he ground up. This sect ion of t he manual cont ains a large amount of informat ion useful for t he preparat ion and assembly of plans for a proj ect . To facilit at e t he product ion of plans and st andardize t he cont ent of bridge plan set s, special provisions, B- Det ails, st andard plans, st andard plan not es, and st andard pay it ems have been prepared by t he Bridge Office. Appendices t o Sect ion 2 ident ify t he mat erial available. As t he name of t he sect ion implies, cont ent for t his sect ion is general in nat ure. Guidance for t he design of specific st ruct ural element s ( e. g. decks, ret aining walls, et c. ) is provided elsewhere in t he manual. Def i ni t i ons For discussion of bridge geomet rics in t his sect ion, roadways are classified as Mainline Highways, Ramps, Local Roads, and Local St reet s. Each of t hese four groups is furt her classified under eit her Urban or Rural Design. The following definit ions apply: Mainline Highways Roadways t hat carry t hrough t raffic lanes for freeways, expressways, and primary and secondary highways. Local Roads Rural roads off t he t runk highway syst em. Local St reet s Urban roads off t he st at e t runk highway syst em. Ramps Segment s of roadway connect ing t wo or more legs at an int erchange. Urban Design Roadways wit h curbs on t he right and/ or left sides. Rural Design Roadways wit hout curbs. Median Widt h The dist ance bet ween t he edges of opposing t hrough t raffic lanes. Auxiliary Lane A lane adj oining a t hrough t raffic lane for a purpose supplement ary t o t hrough t raffic movement such as t ruck climbing, weaving, speed change or t urning. FEBRUARY 2007 LRFD BRI DGE DESI GN 2- 2 2. 1. 2 Br i dge Deck Requi r ement s Gener al Cr i t er i a The widt h of t he bridge deck and t he t ypical sect ion at t he bridge undercrossing are det ermined by t he classificat ion and geomet rics of t he approaching roadway. The geomet rics of t he approaching roadway are t o be carried over and under t he bridge t o t he maximum ext ent pract icable. Rural design is considered t he desirable design and will be used in all rural areas and in urban areas where sufficient right of way is available or can be obt ained. Urban design geomet rics ( curbed roadways) are slight ly more rest rict ive and are t herefore used at locat ions where ext ensive right - of- way cost or ot her unusual condit ions are cont rolling fact ors. The discussion of geomet ric det ails included in t his sect ion describes bridge deck geomet rics separat ely from bridge undercrossing geomet rics. For side clearances at cert ain undercrossing sit uat ions, bot h a desirable and a minimum sect ion are shown. I ncorporat ion of t he desirable sect ion at undercrossings is mandat ory unless approved by t he Preliminary Bridge Plans Engineer. Appl i cat i on of St andar ds The geomet rics shown apply specifically t o new work. However, use of t hese geomet rics is also highly desirable when upgrading or widening exist ing facilit ies and should be incorporat ed in t hese sit uat ions. Bridge deck geomet rics on t he local road syst em must also comply wit h St at e- Aid for Local Transport at ion Operat ions Rules, Chapt er 8820. Responsi bi l i t y The Preliminary Bridge Plans Engineer will be responsible for assuring t hat t he geomet ric st andards in t his sect ion are followed. Where a deviat ion from t he st andard is necessary, a writ t en descript ion of t he deviat ion shall be prepared by t he Preliminary Bridge Plans Engineer and submit t ed t o t he St at e Bridge Engineer when submit t ing t he Preliminary Bridge Plan for accept ance. Br i dge Wi dt h Cr i t er i a Roadway cross sect ions t hat approach bridges will normally provide a clear zone recovery area beside t he t ravel lane for t he benefit of out - of-cont rol vehicles. I t is not economical or pract ical t o carry t hese full clear zone widt hs across bridges. St andard widt hs for bridge shoulders have been set t o balance cost s and safet y. Since t he railing is locat ed wit hin t he clear zone it is considered a hazard and guardrail prot ect ion is required in t he approach area. FEBRUARY 2007 LRFD BRI DGE DESI GN 2- 3 Funct ions of t he shoulder include: Recovery area t o regain cont rol of a vehicle. Emergency parking area for st alled vehicles and escape rout e for st randed mot orist s. Passageway for bicycles and occasional pedest rians. Passageway for emergency vehicles. Parking area for bridge maint enance and inspect ion vehicle ( snooper) . Temporary t raffic lane during deck repairs or overlay const ruct ion. Area for deck drainage and snow st orage. Accommodat es passing of wide oversize loads, especially farm machinery. On t wo- lane highways, t he shoulders provide an escape area t o avoid a head- on collision wit h an oncoming passing vehicle. The following shoulder widt hs for bot h rural and urban design apply t o t runk highway bridges. I n addit ion, t hese st andards apply t o bridges on local roads at a t runk highway freeway int erchange. For local roads and st reet s, t he bridge roadway widt hs are given in t he St at e Aid Manual, Sect ion 5- 892. 210 and t he St at e Aid Operat ions Rules, Chapt er 8820. Except ionally long bridges or bridges wit h a high cost per square foot should be evaluat ed on an individual basis and modificat ions t o t hese st andards are allowed based on j udgment . I n addit ion t o t hese values, t he bridge roadway widt h shall meet t he addit ional requirement s for sight dist ance and sharp curvat ure as specified in Part 4 below. 1) Rural Design a) Two- Lane Rural Design Shoulder widt hs are given in t he t able on Figure 2. 1. 4. 1 and are dependent on t he funct ional classificat ion of t he roadway and t raffic volumes. b) Four- Lane Rural Design i) Right Shoulder 12' - 0" ii) Left Shoulder 6' - 0" c) Six- or Eight - Lane Rural Divided Highway i) Right Shoulder 12' - 0" ii) Left Shoulder 12' - 0" The full inside shoulder allows disabled vehicles in t he left lane t o st op on t he inside shoulder rat her t han t ry t o cross t wo or t hree lanes of t raffic t o get t o t he out side shoulder. d) Mainline Rural Bridge wit h Auxiliary Lane i) Right Shoulder 8' - 0" e) Mainline Rural Bridge wit h Ent rance or Exit Ramps i) Right Shoulder 8' - 0" f) Rural Bridges wit h Turn Lanes FEBRUARY 2007 LRFD BRI DGE DESI GN 2- 4 i) Right Turn Lane ( 1) Right shoulder 6' - 0" ii) Left Turn Lanes ( 1) Adj acent t o a barrier railing: 4' - 0" minimum shoulder, 6' - 0" desirable. g) Rural Ramp Bridges ( one 16' - 0" lane, one- way) i) Right Shoulder 6' - 0" ii) Left Shoulder 4' - 0" On ramp bridges t he dimension from edge of lane t o gut t er is reduced t o prevent t he appearance of a t wo- lane bridge on a one- lane ramp. The roadway widt h is 26' - 0", which allows t raffic t o pass a st alled vehicle. Wit h a 16' - 0" lane t he out side 2' - 0" could, in effect , be considered as part of t he shoulder for a 12' - 0" lane. 2) Urban Design ( Approach Curbs) For urban designs t he bridge gut t er lines shall be aligned wit h t he curb line on t he approaching roadway wit h t he following except ions: a) On four- lane divided highways where t here are no median curbs, t he left shoulder shall be 6' - 0". b) On six- and eight - lane divided highways where t here are no median curbs, t he left shoulder shall be 10' - 0" minimum. c) On one- lane urban ramps ( 16' - 0" approach roadway) , bot h right and left shoulders shall be 4' - 0" ( provides a 24' - 0" roadway) . d) Where an auxiliary lane, ramp, or t aper ext ends ont o a mainline bridge, t he right shoulder shall be 6' - 0". e) The minimum dist ance t o a barrier railing is 6' - 0" desired, 4' - 0" minimum. Urban shoulder widt hs will vary according t o funct ional class, t raffic volumes, scope of work, and qualit y of pavement surface. Typical values are shown in t he Road Design Manual, Tables 4- 4. 01A, 4- 4. 01B, and 4- 4. 01C. Provide a 2' - 0" react ion dist ance t o a raised island t ype median or sidewalk curb where vehicle speeds are 40 mph and under. For design speeds 45 mph and higher, provide a 4' - 0" react ion dist ance. 3) Bus Shoulders Where t he right shoulder has been designat ed as a bus shoulder a 12' - 0" widt h shall be provided across bridges. See Road Design Manual 4- 4. 03 and Table 4- 4. 03A. 4) Addit ional Widt h Crit eria a) Where a ramp ( loop) bridge is on a radius of 190' - 0" or less, or when t he volume of t rucks is 10% or great er, t he effect ive t raffic FEBRUARY 2007 LRFD BRI DGE DESI GN 2- 5 lane is increased from 16' - 0" t o 18' - 0" in widt h t o accommodat e t ruck t urning movement s. I ncrease t he widt h of t he ramp bridge accordingly. b) For curved bridges longer t han 100 feet , check t he horizont al st opping sight dist ance and increase t he inside shoulder widt h up t o a maximum of 10' - 0". See Road Design Manual, Chapt er 3 for calculat ion of t his dist ance. The 2001 edit ion of t he AASHTO book, A Policy on Geomet ric Design of Highways and St reet s, changed t he height of obj ect from 6" ( muffler) t o 2' - 0" ( t ail light ) . Table 2. 1. 2. 1 gives widt hs required for a cont inuously curving bridge for various design speeds and curvat ure, and applies only where t he line of sight is blocked by t he railing. Tabl e 2.1.2. 1 Shoul der Wi dt h Requi r ement s f or Cur v ed Br i dges SHOULDER WI DTH FOR DEGREE OF CURVATURE LI STED DESI GN SPEED 6 FT. 8 FT. 10 FT. 70 mph t o 0o 45 > 0o 45 t o 1o > 1o 60 mph t o 1o 15 > 1o 15 t o 2o > 2o 50 mph t o 2o 30 > 2o 30 t o 3o 15 > 3o 15 40 mph t o 5o 30 > 5o 30 t o 7o > 7o c) For bridges on t apers, t he t aper should begin or end at a pier or an abut ment , or cont inue across t he ent ire lengt h of t he bridge. Ext ra widt h t o eliminat e or simplify a t aper or curvat ure is permissible where j ust ified by simplified design and const ruct ion. Cr oss Sl o