Table of Contents
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- 101.1 Purpose
- 101.2 Limitations of the Design Manual
- 101.3 Policy
- 101.4 Applicable Design Specifications and Standards
- 101.4.1 Design Specification Reference Nomenclature
- 101.4.2 Design Specifications
- 101.4.3 AASHTO Interim Specifications and New Editions
- 101.4.4 Deviations from Specifications
- 101.4.5 Order of Precedence
- 101.4.6 Modifications to the Design Manual
- 101.4.7 Additional Reference Manuals and Documents
- 101.5 Terms
- 101.5.1 Bridge Types
- 101.5.2 Roadway Types
- 101.5.2.1 Functional Classification
- 101.5.2.2 National Highway System
- 101.5.3 Project Types
- 101.6 FHWA Stewardship and Oversight Agreement
- 101.7 Computer Software
- 101.8 Feedback
- 101.9 References
Section 102 Bridge Design Submission Requirements
- 102.1 Plan Presentation
- 102.1.1 Drafting Standards
- 102.1.2 Plan Sheet Sequence
- 102.1.3 Bridge Sheet Preparation
- 102.1.3.1 General and Project Notes
- 102.1.3.2 Bridge Plan and Elevation
- 102.1.3.3 Lay-Out Plan
- 102.1.3.4 Other Plans
- 102.1.4 Bridge Number
- 102.2 Special Provisions Development
- 102.3 Quantities and Cost Estimates
- 102.4 Construction Schedule
- 102.5 Bridge Design Procedures
- 102.5.1 Quality Assurance and Quality Control
- 102.5.2 Designed-In Value
- 102.5.2.1 Alternatives Analysis
- 102.5.2.2 Life-Cycle Cost Analyses
- 102.5.3 Documentation of Design
- 102.5.4 Design Exceptions and Design Variances
- 102.5.5 Chronology of Submissions
- 102.6 Preliminary Design
- 102.6.1 Hydrologic and Hydraulic Report
- 102.6.2 Scour Evaluation Report
- 102.6.3 Foundation Reports
- 102.6.4 Conceptual Type, Size, and Location Plans
- 102.6.5 Type, Size, and Location Submission
- 102.6.5.1 Type, Size, and Location Submission Requirements
- 102.7 Preliminary Construction Plans
- 102.8 Semi-Final Construction Plans
- 102.9 Final Construction Plans
- 102.10 Plans, Specifications, and Estimate
- 102.11 Bid-Cycle Requirements
- 102.11.1 Addenda
- 102.11.2 Bid Opening and Bid Review
- 102.12 References
Section 103 Bridge Geometry and Structure Type Selection
- 103.1 Introduction
- 103.2 Terms
- 103.3 Bridge Geometric Design Requirements
- 103.3.1 Bridge Length
- 103.3.2 Minimum Width of Bridges
- 103.3.2.1 Shoulder Width Requirements for Deck Drainage
- 103.3.2.2 Sidewalks
- 103.3.2.3 Bicycle and Shared Use Facilities
- 103.3.2.4 Superelevation
- 103.3.3 Protection for Median Gap of Parallel Structures
- 103.3.4 Horizontal Clearance and Pier Protection
- 103.3.4.1 Over Rivers, Streams, Wetlands, and Floodplains
- 103.3.4.2 Over Roadways / Grade Crossings
- 103.3.4.3 Over Railroads
- 103.3.5 Vertical Clearance
- 103.3.5.1 Over Rivers, Streams, Wetlands, Floodplains
- 103.3.5.2 Over Roadways / Grade Crossings
- 103.3.5.3 Over Railroads
- 103.3.6 Bridge Skew
- 103.3.7 Approach Slabs
- 103.4 Structure Type Selection
- 103.4.1 Bridge Types
- 103.4.1.1 Structural Steel
- 103.4.1.2 Concrete Bridges
- 103.4.1.3 Timber Bridges
- 103.4.1.4 Culverts
- 103.4.2 Selection of Superstructure Type
- 103.4.2.1 Spans less than 20 feet
- 103.4.2.2 Spans from 20 feet to 30 feet
- 103.4.2.3 Spans from 30 feet to 90 feet
- 103.4.2.4 Spans from 90 feet to 165 feet
- 103.4.2.5 Spans greater than 165 feet
- 103.4.1 Bridge Types
- 103.5 Construction
- 103.5.1 Future Re-decking Considerations
- 103.5.2 Consideration for Future Widening
- 103.5.3 Hauling Permits
- 103.5.4 Maintenance of Traffic
- 103.5.5 Inspectability
- 103.6 Substructure Type Selection
- 103.6.1 General Considerations
- 103.6.2 Abutments and Wingwalls
- 103.6.3 Piers
- 103.7 Retaining Walls
- 103.7.1 Wall Types
- 103.7.1.1 Post and Plank Walls
- 103.7.1.2 Sheet Pile Walls
- 103.7.1.3 Reinforced Concrete Walls
- 103.7.1.4 Anchored Walls
- 103.7.1.5 Proprietary Retaining Walls
- 103.7.1 Wall Types
- 103.8 Bridge Rehabilitation versus Replacement Selection Guidelines
- 103.8.1 Cost
- 103.8.2 Safety
- 103.8.3 Bridge Type
- 103.8.4 Bridge Standards
- 103.8.5 Feature Crossed
- 103.8.6 Comprehensive Assessment of Rehabilitation versus Replacement
- 103.9 Accelerated Bridge Construction
- 103.9.1 Decision-Making/Planning Process
- 103.9.1.1 ABC Rating Score
- 103.9.1.2 FHWA Decision Flowcharts / ABC AHP Software Tool
- 103.9.1.3 Emergency Projects
- 103.9.1.4 Repair and Rehabilitation Projects
- 103.9.2 ABC Methods/Techniques
- 103.9.2.1 Foundation and Wall Elements
- 103.9.2.2 Rapid Embankment Construction
- 103.9.2.3 Prefabricated Bridge Elements and Systems
- 103.9.2.4 Structural Placement Methods
- 103.9.2.5 Fast-Track Contracting
- 103.9.1 Decision-Making/Planning Process
- 103.10 Requirements for the Design of Highway Bridges over Railroads
- 103.11 References
Section 104 Hydrology and Hydraulics
- 104.1 Introduction
- 104.1.1 Terms
- 104.1.2 Coordination
- 104.1.3 Design Responsibilities
- 104.1.4 Field Data Collection
- 104.1.5 Topographic Survey and Extent of Hydraulic Study
- 104.2 Hydrology
- 104.2.1 Introduction
- 104.2.2 Documentation
- 104.2.3 Precipitation
- 104.2.3.1 The Rational Method
- 104.2.3.2 Delaware Regression Method (SIR 2006-5146)
- 104.2.3.3 Published Reports
- 104.2.3.4 Flood-Frequency Analysis of Recorded Stream Gage Data
- 104.2.3.5 Other Methods/Models
- 104.2.4 Methodology Selection Guidance
- 104.2.5 Design Flood Frequency
- 104.2.6 Confidence Intervals
- 104.2.7 Frequency Mixing (Probability of Coincidental Occurrence)
- 104.3 Hydraulics
- 104.3.1 Culverts
- 104.3.1.1 Sizing
- 104.3.1.2 Site Conditions and Skew
- 104.3.1.3 Shape/Material
- 104.3.1.4 Environmental Considerations
- 104.3.2 Bridges
- 104.3.2.1 Sizing
- 104.3.2.2 Site Conditions and Skew
- 104.3.2.3 Shape/Material
- 104.3.3 Hydraulics for Dam Safety Projects
- 104.3.3.1 Sizing
- 104.3.3.2 Site Conditions and Bridges Near Non-regulated Dams
- 104.3.3.3 Shape/Material
- 104.3.3.4 Dam Safety Regulations
- 104.3.4 Tidal Hydraulics – Bridges and Culverts
- 104.3.4.1 General
- 104.3.4.2 Use of Qualified Coastal Engineers
- 104.3.4.3 Tidal Hydraulic and Scour Analysis
- 104.3.4.4 Tidal Modeling
- 104.3.4.5 Freeboard for Tidal Bridges
- 104.3.4.6 Sea Level Rise
- 104.3.4.7 Tidal Hydraulics References
- 104.3.5 Hydraulics Methodologies and Software
- 104.3.5.1 HEC-RAS
- 104.3.5.2 HY-8
- 104.3.5.3 Two-Dimensional Hydraulic Models
- 104.3.1 Culverts
- 104.4 Scour Evaluation and Protection
- 104.4.1 Scour Investigation
- 104.4.2 Scour Components
- 104.4.2.2 Long-Term Scour
- 104.4.2.3 Contraction Scour
- 104.4.2.4 Local Scour
- 104.4.3 Scour Flood Magnitude
- 104.4.4 Design Considerations
- 104.4.4.1 Scour Due to Lateral Movement
- 104.4.4.2 Spread Footings
- 104.4.4.3 Dams and Backwater
- 104.4.4.4 Streambed Material
- 104.4.4.5 Scour in Cohesive Soils
- 104.4.4.6 Scourability of Rock
- 104.4.5 Scour Countermeasures
- 104.4.5.1 Riprap Protection
- 104.4.5.2 Guide Banks
- 104.4.5.3 Scour Protection at Culverts
- 104.4.6 Scour Evaluation Documentation
- 104.4.7 Scour Plan Presentation
- 104.5 Streams
- 104.5.1 Stream Stability Analysis
- 104.5.2 Bank Protection
- 104.5.3 Channel Modifications
- 104.5.4 Stream Diversions
- 104.5.5 Ice and Debris
- 104.6 Hydrologic and Hydraulic Report
- 104.6.1 Hydraulic Summary Data Sheet and Definitions
- 104.7 Plan Presentation
- 104.8 Laws, Policy, Regulations and Permits
- 104.8.1 FEMA Compliance
- 104.8.2 New Castle County Requirements
- 104.8.3 Tax Ditches
- 104.8.4 Risk Assessment or Analysis
- 104.8.5 Aids to Navigation
- 104.8.6 DelDOT Project Development Manual
- 104.9 References
Appendix 104-1: Hydraulic Field Assessment Checklist
Appendix 104-2: Hydraulic Survey Form
Appendix 104-3: H&H Report Hydraulic Data Summary Sheet
Appendix 104-4: H&H Report Sample Format
Section 105 Geotechnical Investigations
- 105.1 Introduction
- 105.2 Terms
- 105.3 Subsurface Investigations
- 105.3.1 Estimating Soil and Rock Properties
- 105.3.2 Estimating Ground Water Table Elevation
- 105.3.3 Estimation of Bearing Capacity
- 105.3.4 Estimation of Settlement
- 105.3.5 Estimated Depth of Unsuitable Materials
- 105.3.6 Global Stability
- 105.3.7 Corrosive Environment
- 105.3.8 Lateral Squeeze
- 105.4 Subsurface Investigation Request
- 105.4.1 Request for Test Borings
- 105.4.1.1 Quantity and Location of Structural Borings
- 105.4.1.2 Depth of Structural Borings
- 105.4.2 Boring Logs
- 105.4.3 Coordination for Soils/Rock Testing
- 105.4.3.1 Typical Soil Tests
- 105.4.3.2 Typical Rock Tests
- 105.4.1 Request for Test Borings
- 105.5 Geotechnical Report
- 105.6 Foundation Report
- 105.6.1 Concise Foundation Report
- 105.6.2 Foundation Report Submittals
- 105.6.3 Quality Assurance and Quality Control
- 105.6.4 Geotechnical Design References
- 105.7 References
Section 106 Final Design Consideration – Superstructure
- 106.1 Introduction
- 106.2 Terms
- 106.3 Design Loads
- 106.3.1 Dead Loads
- 106.3.1.1 Considerations for Deck Haunch
- 106.3.1.2 Distribution of Dead Loads
- 106.3.2 Live Loads
- 106.3.1 Dead Loads
- 106.4 Bridge Decks
- 106.4.1 Deck Type Considerations
- 106.4.2 Concrete Decks
- 106.4.2.1 Concrete Deck Design Considerations
- 106.4.2.2 Deck Thickness
- 106.4.2.3 Deck-Reinforcing Steel
- 106.4.2.4 Deck Haunch
- 106.4.2.5 Concrete Cover
- 106.4.2.6 Deck Placement Sequence
- 106.4.2.7 Deck Overhangs
- 106.4.2.8 Concrete Deck Finishing
- 106.4.2.9 Future Wearing Surface/Overlays
- 106.4.2.10 Concrete Deck Construction Joints
- 106.4.2.11 Temporary Protective Shield
- 106.4.3 Finished Deck Elevations
- 106.5 Bridge Barriers and Railings
- 106.5.1 DelDOT Standard Bridge Barrier and Railing Applications
- 106.5.2 Bridge Barrier Design Considerations
- 106.5.3 Protective Screening, Shielding, and Fencing
- 106.5.4 Bridge Lighting
- 106.6 Deck Joints
- 106.6.1 Jointless Bridges
- 106.6.2 Strip Seal Joints
- 106.6.3 Steel Finger Joints
- 106.6.4 Longitudinal Joints
- 106.7 Approach Slab Design
- 106.7.1 Approach Slab Geometry and Design Requirements
- 106.8 Steel Superstructure Design Considerations
- 106.8.1 Structural Steel – Material Requirements
- 106.8.1.1 Grade 50 Steel
- 106.8.1.2 Weathering Steel
- 106.8.1.3 High-Performance Steels
- 106.8.2 Fatigue and Fracture Considerations
- 106.8.2.1 Redundancy Requirements
- 106.8.2.2 Welding and Weld Procedures
- 106.8.3 Steel-Rolled Beams and Plate Girders
- 106.8.3.1 Minimum Plate Thicknesses
- 106.8.3.2 Plate Girder Geometric Proportionality – General Practice
- 106.8.4 Shear Connectors
- 106.8.5 Stiffeners, Diaphragms, and Bracing
- 106.8.6 Bolted Connections
- 106.8.7 Protective Coatings
- 106.8.7.1 Paint Systems
- 106.8.7.2 Galvanization
- 106.8.8 Steel-Plate Girder and Rolled Beam Bridges
- 106.8.8.1 Method of Analysis
- 106.8.8.2 Diaphragms/Cross-Bracing
- 106.8.8.3 Bearings for Horizontally Curved and/or Skewed Steel Superstructures
- 106.8.9 Erection Analysis and Erection Plans
- 106.8.9.1 Requirements for Designer
- 106.8.9.2 Erection Submittal Requirements for Contractor’s Engineer
- 106.8.10 Deck Placement Sequence Analysis and Design
- 106.8.1 Structural Steel – Material Requirements
- 106.9 Prestressed Concrete Bridge Superstructures
- 106.9.1 Materials
- 106.9.2 Design Methodology
- 106.9.2.1 Design Methodology
- 106.9.3 Diaphragm Requirements
- 106.9.4 Minimum Spacing of Prestressing Tendons
- 106.9.5 Tensile Stresses Due to Prestressing
- 106.9.6 De-bonding Versus Draping
- 106.9.7 Reinforcement
- 106.9.7.1 Composite Shear Reinforcement
- 106.9.7.2 Anchorage Zone Reinforcement
- 106.9.8 Skew Effects
- 106.9.8.1 Grade and Cross-Slope Effects
- 106.9.8.2 Horizontal Curve and Flare Effect
- 106.9.9 Camber
- 106.9.9.1 Consideration for Staged Construction Camber
- 106.9.9.2 Simple Spans Made Continuous
- 106.10 Bearings
- 106.10.1 Elastomeric Bearings
- 106.10.1.1 Steel-Reinforced Elastomeric Bearings
- 106.10.2 High-Load Multi-Rotational Bearings
- 106.10.2.1 Pot Bearings
- 106.10.2.2 Disc Bearings
- 106.10.2.3 Spherical Bearings
- 106.10.2.4 Mechanical Bearings
- 106.10.3 Guidelines for Bearing Selection
- 106.10.3.1 Bearing Type Preferences
- 106.10.3.2 Feasibility due to Fabrication, Installation and Testing Limitations
- 106.10.4 Loads, Rotation and Translation
- 106.10.5 Design Requirements
- 106.10.5.1 Elastomeric Bearings
- 106.10.5.2 High-load Multi-Rotational Bearings
- 106.10.5.3 Design Limitations
- 106.10.6 Consecutively Fixed Piers
- 106.10.7 Accommodations for Future Bearing Replacement
- 106.10.8 Bearings for Horizontally-Curved and/or Skewed Bridges
- 106.10.9 Anchorage to Structure
- 106.10.9.1 Sole Plates
- 106.10.9.2 Masonry Plates and Anchor Rods
- 106.10.10 Lateral Restraint
- 106.10.11 Uplift Restraint
- 106.10.12 Bearing Schedule
- 106.10.1 Elastomeric Bearings
- 106.11 References