WORKSHOP ON PLAN OF ACTION FOR SCOUR CRITICAL BRIDGES

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WORKSHOP ON PLAN OF ACTION FOR SCOUR CRITICAL
BRIDGES
Transportation Research Board 2002 Annual
Meeting Sponsored By A2A03 Committee on
Hydrology, Hydraulics and Water Quality
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• SESSIONS 582 AND 610
• J. Sterling Jones FHWA
• Peter F. Lagasse Ayres Associates
• Jorge E. Pagan-Ortiz FHWA
• David R. Pearson GKY Associates

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OVERVIEW AND UPDATES TO HEC 18, 20, AND 23
P.F. Lagasse, Ph.D., P.E. Transportation Research
Board 2002 Annual Meeting Sponsored By A2A03
Committee on Hydrology, Hydraulics and Water
Quality
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• BRIDGE SCOUR
• CATASTROPHIC FAILURES
• Schoharie Creek, New York - 1987
• Hatchie River, Tennessee - 1989
• I-5 (Los Gatos Creek), California - 1995

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• BRIDGE SCOUR
• A WIDESPREAD PROBLEM
• 481,251 Bridges over Water
• 25,858 Scour Critical
• 88,686 Unknown Foundations

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• A DECADE OF RESEARCH EDUCATION AND TRAINING
• HEC-18 Bridge Scour
• HEC-20 Stream Stability
• HEC-23 Countermeasures
• ASCE Compendium on Bridge Scour
• 1998 European Scanning Review
• 1999 New Zealand Scanning Review

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COMPREHENSIVE METHODOLOGY
HEC-20
HEC-18
HEC-23
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• HEC-18 REVISIONS
• (FOURTH EDITION)

• Reorganize by Topic
• Move Countermeasure Design to HEC-23
• Pier Scour in Coarse Material (K4)
• Scour for Complex Pier Foundations
• Pressure Flow Scour
• Alternative Approaches for Abutment Scour
• Special Considerations
• - Plan of Action
• - Item 113 Coding Revisions
• - Scour in Cohesive Soils
• - Scour in Rock

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• HEC-20 REVISIONS
• (THIRD EDITION)

• Move Countermeasure Selection and Design to
  HEC-23
• Stream Reconnaissance, Classification, and
  Response
• Rapid Assessment Method
• Quantitative Analysis Techniques
• - Lateral Stability (Meander)
• - Vertical Stability (Degradation)
• - Sediment Continuity
• Channel Restoration Concepts
• Geotechnical Considerations for Bank Stability

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• HEC-23 REVISIONS
• (SECOND EDITION)

• Becomes the Primary Reference for
• Countermeasure Design
• Strategies for Plan of Action
• Hydraulic Analysis
• - Physical Modeling
• - Scour at Transverse Structures
• - Scour at Longitudinal Structures
• Special Considerations for Riprap and Filter
  Design

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• HEC-23 REVISIONS
• (SECOND EDITION)

• Biotechnical Engineering
• Guidance from Outside U.S.
• Instrumentation and Monitoring
• Additional Design Guidelines
• - Design Procedure for Grout Filled Mattresses
• - Modular Design for Concrete Armor Units
• - Revetment Guidelines from HEC-11

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• TRAINING COURSE REVISIONS

• Stream Stability and Scour (HEC-18 20)
• Countermeasure Design (HEC-23 and DP 97)
• Update 1-Day Bridge Inspectors Course
• Develop Course Materials for HDS6

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• HDS 6 REVISIONS

• Update Technology from 1970s to 1990s
• Expanded Sediment Transport Chapter
• - Comprehensive Comparison of Formulas
• - Formula Selection based on Transport Mode
• - New Sediment Transport Relationships
• More Channel Response Case Studies
• Better Integration with HEC-18, -20, -23
• To Be Issued as HDS-6

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• HDS 6

• River Engineering for Highway Encroachments
• Highways in the River Environment
• REHIRE

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STREAM STABILITY AND SCOUR AT HIGHWAY BRIDGES
NHI COURSE 135046
Overall Course Learning Objectives 1. Identify
stream instability and scour problems at
bridges 2. Conduct a stream stability
reconnaissance 3. Classify the stream, identify
potential problems, and conduct a qualitative
analysis of response 4. Calculate long-term
degradation quantities
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STREAM STABILITY AND SCOUR AT HIGHWAY BRIDGES NHI
Course 135046

• 5. Calculate general and local scour at bridge
  piers and abutments for simple and complex
  substructures
• 6. Plot and evaluate the total scour prism
• 7. Define and compare channel restoration and
  channel rehabilitation concepts
• 8. Draft a Plan of Action for correcting stream
  instability and scour problems

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COUNTERMEASURE DESIGN FOR BRIDGE SCOUR AND STREAM
INSTABILITY NHI Course 135048

• Overall Course Learning Objectives
• 1. Prepare a Plan of Action for correcting stream
  instability and scour problems considering a
  range of countermeasure options and strategies
• 2. Select appropriate countermeasures considering
  functional applications and river
  characteristics
• 3. Estimate scour at longitudinal and transverse
  structures

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COUNTERMEASURE DESIGN FOR BRIDGE SCOUR AND STREAM
INSTABILITY NHI Course 135048

• Overall Course Learning Objectives
• 4. Describe the advantages and disadvantages of
  biotechnical engineering
• 5. Describe a range of alternatives to
  conventional riprap and filter techniques for
  local scour protection
• 6. Design channel instability and bridge scour
  countermeasures for specific stream instability
  or scour problems

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COUNTERMEASURE DESIGN FOR BRIDGE SCOUR AND STREAM
INSTABILITY NHI Course 135048

• Overall Course Learning Objectives
• 7. Describe other countermeasures for stream
  instability and scour and evaluate their
  performance
• 8. Given a scour critical bridge, select and
  design a monitoring program to reduce the risk
  from scour
• 9. Integrate portable and fixed instruments into
  a monitoring program