Table of Contents

Section 101 Introduction

101.1 Purpose

101.2 Limitations of the Design Manual

101.3 Modifications to the Design Manual

101.4 Policy

101.5 Applicable Design Specifications and Standards

101.5.1 Design Specification Reference Nomenclature

101.5.2 Design Specifications

101.5.3 AASHTO Interim Specifications and New Editions

101.5.4 Deviations from Specifications

101.5.5 Order of Precedence

101.5.6 Additional Reference Manuals and Documents

101.6 Terms

101.6.1 Bridge Types

101.6.2 Roadway Types

101.6.2.1 Functional Classification

101.6.2.2 National Highway System

101.6.3 Project Types

101.7 FHWA Stewardship and Oversight Agreement

101.8 Computer Software

101.9 Feedback

101.10 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

103.5 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

103.8 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

103.10 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

104.4 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

105.5 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

106.4 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

106.9 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 Tensile Stresses at Service Limit State After Losses

106.9.8 Reinforcement

106.9.8.1 Composite Shear Reinforcement

106.9.8.2 Anchorage Zone Reinforcement

106.9.9 Skew Effects

106.9.9.1 Grade and Cross-Slope Effects

106.9.9.2 Horizontal Curve and Flare Effect

106.9.10 Camber

106.9.10.1 Consideration for Staged Construction Camber

106.9.10.2 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

106.11 References

Section 107 Final Design Considerations – Substructure

107.1 Introduction

107.2 Terms

107.3 Foundation Design

107.3.1 Settlement Considerations

107.3.2 Spread Footing Foundations

107.3.3 Deep Foundations

107.3.4 Pile Foundations

107.3.4.1 Precast-Prestressed Concrete Piles

107.3.4.2 Steel Pipe Piles

107.3.4.3 Steel Shell and Cast-in-Place Piles

107.3.4.4 Steel H-Piles

107.3.4.5 Timber Piles

107.3.4.6 Drilled Shaft Foundations

107.3.4.7 Micropiles, Auger-cast Piles, and New Pile Technologies

107.3.4.8 Selection of Deep Foundation Type

107.3.4.9 Pile-Bearing Capacity

107.3.5 Additional Foundation Details

107.3.5.1 Design Footing and Pile Resistance

107.3.5.2 Scour

107.3.5.3 Stepped Footings

107.3.5.4 Corrosion and Deterioration

107.4 Substructure Design

107.4.1 Abutment Design

107.4.1.1 Semi-Integral Abutments

107.4.1.2 Integral Abutments

107.4.1.3 Reinforced-Concrete Stub Abutments

107.4.1.4 Reinforced-Concrete Cantilever Abutments

107.4.1.5 Abutment, Backwall, and Wingwall Details

107.5 Pier Design

107.5.1 Pier Analysis and Design

107.5.2 Fixity Considerations

107.5.3 Pier Detailing

107.5.4 Pile Bents

107.5.5 Protective Sealing of Surfaces

107.6 Retaining Wall Design

107.6.1 Mechanically Stabilized Earth Walls

107.6.1.1 Select Granular Backfill

107.6.1.2 Designer Responsibility

107.6.1.3 MSE Wall Manufacturer Responsibility

107.6.2 Reinforced-Concrete Cantilevered Walls

107.6.3 Post and Plank Walls

107.6.4 Sheet-Pile Walls

107.6.4.1 Steel Sheet Piles

107.6.4.2 Concrete Sheet Piles

107.7 Culvert Design

107.7.1 Culvert Hydraulics

107.7.2 Culvert Foundation Design

107.7.3 Concrete Culverts

107.7.3.1 Precast Concrete Box Culverts

107.7.3.2 Cast-In-Place Concrete Box Culverts

107.7.3.3 Reinforced Concrete Rigid Frames

107.7.3.4 Concrete Arches

107.7.3.5 Precast Proprietary Structures

107.7.4 Pipe Culverts

107.7.5 Culvert Details

107.7.5.1 Headwalls

107.7.5.2 Wingwalls

107.7.5.3 Cutoff Walls

107.7.5.4 Scour Aprons

107.7.5.5 Guardrail Attachments

107.7.5.6 Protective Sealing of Surfaces

107.8 Architectural Treatments

107.9 Temporary Excavation Support Systems

107.10 References

Section 109 Bridge Preservation Strategies

109.1 Introduction

109.1.1 Bridge Inspections and Load Ratings

109.1.2 Environmental Considerations

109.1.3 Rehabilitation Design Criteria

109.2 Material Testing

109.2.1 Concrete

109.2.1.1 Compressive Strength

109.2.1.2 Alkali-Silica Reaction Evaluation

109.2.1.3 Chloride Content

109.2.1.4 Freeze-Thaw

109.2.1.5 Half-Cell Potential

109.2.1.6 Petrographic Analysis

109.2.2 Steel

109.2.2.1 Chemical Analysis

109.2.2.2 Mechanical Properties

109.3 Concrete Bridge Decks

109.3.1 Condition Survey

109.3.1.1 Visual Inspection

109.3.1.2 Delamination Survey

109.3.1.3 Reinforcing Corrosion Survey

109.3.1.4 Deck Coring

109.3.2 Deck Evaluation

109.3.3 Deck Removal Methods

109.3.4 Preventive Maintenance and Rehabilitation

109.3.4.1 General

109.3.4.2 Patching

109.3.4.3 Low-Permeability Overlays

109.3.4.4 Widening and Partial-Width Re-decking

109.3.4.5 Barrier Reconstruction

109.3.5 Concrete Deck Replacement

109.3.5.1 General

109.3.5.2 Cast-in-Place Concrete

109.3.5.3 Precast Concrete

109.4 Steel Grid Decks

109.4.1 General

109.4.2 Existing Steel Grid Deck Evaluation

109.4.2.1 Connection Failure and Fatigue

109.4.2.2 Corrosion

109.4.2.3 Delamination of Surfacing

109.4.2.4 Reduced Skid Resistance

109.4.3 Design Considerations

109.5 Timber Decks

109.5.1 General

109.5.2 Design Considerations

109.6 Safety Considerations

109.7 Deck Joints

109.8 Approach Slabs

109.9 Slabs, Beams, and Girders

109.9.1 Reinforced-Concrete Slabs

109.9.1.1 General

109.9.1.2 Design Considerations

109.9.1.3 Repair and Strengthening

109.9.2 Prestressed Concrete Beams

109.9.2.1 General

109.9.2.2 Design Considerations

109.9.2.3 Repair Methods

109.9.3 Steel Beams and Girders

109.9.3.1 General

109.9.3.2 Design Considerations

109.9.3.3 Repair and Strengthening

109.9.3.4 Fatigue Evaluation and Repair

109.9.3.5 Fire Damage

109.9.3.6 Surface Preparation and Painting

109.9.3.7 Cathodic Protection

109.9.3.8 Heat Straightening

109.10 Bearings

109.11 Foundation and Substructure

109.11.1 General

109.11.2 Design Considerations

109.11.3 Repair Methods

109.11.3.1 Bearing Seat Repairs

109.11.3.2 Post-Tensioning Repairs

109.11.3.3 Underwater and Splash-Zone Repairs

109.11.3.4 Pile Repairs

109.11.3.5 Scour and Undermining Repairs

109.11.4 Stabilization and Underpinning

109.12 Retaining Walls

109.12.1 General

109.12.2 Design Considerations

109.12.3 Repair Methods

109.13 Culverts

109.13.1 General

109.13.2 Design Considerations

109.13.3 Repair Methods

109.14 Utilities

109.15 Moveable Bridges

109.16 References

Section 110 Ancillary Structures

110.1 Introduction

110.2 Terms

110.3 Overhead Sign Structures

110.3.1 Overhead Sign Structure Types and Geometrics

110.3.1.1 Cantilever Sign Structures

110.3.1.2 Span-Type Sign Structures

110.3.1.3 Bridge-Mounted Signs

110.3.2 General Design Considerations

110.3.2.1 Designer Responsibility

110.3.2.2 Materials

110.3.2.3 Design Criteria

110.3.2.4 Consideration for Future Conditions

110.3.3 Design Process

110.3.4 Foundations

110.4 Sound Barrier Walls

110.4.1 Design Criteria

110.4.1.1 Designer Responsibility

110.4.1.2 General Criteria

110.4.1.3 Materials

110.4.1.4 Detailing Connections

110.4.1.5 Loads

110.4.1.6 Miscellaneous

110.4.2 Foundations

110.5 References

Section 111 Construction Coordination

111.1 Working Drawings

111.1.1 Required Working Drawings

111.1.2 Working Drawings Review Procedure

111.1.2.1 Consultant Review of Working Drawings

111.1.3 Technical Guidelines for Review of Working Drawings

111.2 Contractor Requests for Information

111.3 Value Engineering Proposals (by Contractor)

111.4 Plan Revisions

111.5 As-Built Drawings

111.6 References