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Standardised Bridge Barrier Designs

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Publication no: AP-R445-13 Pages: 239
Published: 25 October 2013


Consistency in the design of traffic barriers for bridges has been identified as a major issue in current practice throughout Australia and New Zealand. The need for standard solutions was recognised by road jurisdictions, consultants and contractors during the Austroads 6th Bridge Conference Workshop on Bridge Barriers, held in 2006. The main areas of concern are the determination of appropriate barrier performance levels, structural design criteria, the lack of standard barrier design details, guidance on retrofitting existing bridge barriers, bridge approach barriers and overpass bridge support protection.

This report addresses these issues and provides a set of design guidelines for the identified areas. These guidelines will assist bridge designers, contractors and jurisdictions to provide consistency and cost savings in the selection and development of relevant bridge barriers throughout Australia and New Zealand. Existing jurisdictional technical specifications, standards and guidelines, as well as outcomes from extensive expert discussions have been incorporated in this report. Key areas of future work to be undertaken after the on-going revision of AS 5100 has been published are also included.


Table of Contents

1 Introduction
  • 1.1 Background
  • 1.2 Aims
  • 1.2.1 Overall Aims
  • 1.2.2 2010–11 Assess Current Practice
  • 1.2.3 2011–12 Develop Guidelines and Identify Research
  • 1.2.4 2012–13 Finalise Guidelines and Recommend Research
  • 1.3 Scope
  • 1.4 Outline
2 Discussions on the Development of the Guidelines
  • 2.1 Jurisdictions’ Current Practice
  • 2.1.1 Common Bridge Barrier Systems
  • 2.1.2 Design Guidelines
  • 2.1.3 Issues and Recommendations
  • 2.2 Current Design Standard AS 5100
  • 2.3 Computer Simulation
  • 2.4 Safe System Approach
  • 2.4.1 Safe System
  • 2.4.2 Contribution of Bridge Barrier Design to the Safe System
  • 2.5 Development of the Guidelines
  • 2.5.1 Guidelines for Selection of Bridge Barrier Performance Levels (Section 3)
  • 2.5.2 Bridge Barrier Design Procedure (Section 4)
  • 2.5.3 Standardised Bridge Barrier Designs (Section 5)
  • 2.5.4 Guidelines for Bridge Barrier Retrofitting (Section 6)
  • 2.5.5 Guidelines for Bridge Approach Barriers (Section 7)
  • 2.5.6 Guidelines for Bridge Support Protection Barriers (Section 8)
3 Selection of Bridge Barrier Performance Levels
  • 3.1 General Procedure
  • 3.1.1 Bridge Barrier Performance Levels
  • 3.1.2 Site Condition Categories
  • 3.2 Criteria for Site Condition CAT1
  • 3.3 Criteria for Site Condition CAT2
  • 3.4 Criteria for Site Condition CAT3
  • 3.5 CAT1 Method
  • 3.6 CAT2 Method – Chart-based Procedure
  • 3.6.1 Determine AADT and Portion of Commercial Vehicles
  • 3.6.2 Determine Adjusted AADT
  • 3.6.3 Determine Barrier Performance Level
  • 3.6.4 Example 1
  • 3.7 CAT3 Method – Specification Standards and B/C Analysis
  • 3.7.1 Specification Standards for Medium Performance Level
  • 3.7.2 Specification Standards for High Performance Level
  • 3.7.3 Specification Standards for Special Performance Level
  • 3.7.4 Benefit-cost Analysis
  • 3.7.5 Example 2
4 Bridge Barrier Design Procedure
  • 4.1 Barrier Performance Specifications
  • 4.2 Structural Design Criteria
  • Contact lengths
  • Design forces
  • Minimum effective heights
  • 4.3 Selection of Bridge Barrier Types
  • 4.3.1 Concrete Barriers
  • 4.3.2 Post-and-rail Barriers
  • 4.3.3 Combined Concrete Parapet and Metal Rails
  • 4.3.4 Acceptance Criteria for Non-standard Bridge Traffic Barriers
  • 4.4 Concrete Parapets
  • 4.4.1 Barrier Geometry
  • 4.4.2 Design Process
  • 4.4.3 Design of Bridge Cantilevered Deck Slab
  • 4.5 Post-and-rail Barriers
  • 4.5.1 Barrier Geometry
  • 4.5.2 Design Process
  • 4.5.3 Design of Bridge Cantilevered Deck Slab
  • 4.6 Concrete Parapet and Metal Rail
  • 4.6.1 Barrier Geometry
  • 4.6.2 Design Process
  • 4.6.3 Design of Bridge Cantilevered Deck Slab
  • 4.7 Design Examples
  • 4.7.1 Design Example 1: Concrete Parapet – Medium Performance Level
  • 4.7.2 Design Example 2: Post-and-rail Barrier – Regular Performance Level
  • 4.7.3 Design Example 3: Combined Concrete Parapet and Metal Rail – Medium Performance Level
5 Standardised Bridge Barrier Designs
  • 5.1 Introduction
  • 5.2 Bridge Barrier Designs Currently in Use in Jurisdictions
  • 5.2.1 Low Performance Level Barriers
  • 5.2.2 Regular Performance Level Barriers
  • 5.2.3 Medium Performance Level Barriers
  • 5.2.4 High Performance Level Barriers
  • 5.2.5 Special Performance Level Barriers
  • 5.3 Specific Design Requirements from Jurisdictions
  • 5.4 Selection of Bridge Barrier Concept Designs for Standardisation
6 Retrofitting of Existing Bridge Barriers
  • 6.1 Introduction
  • 6.2 Reasons for Retrofitting Existing Bridge Barriers
  • 6.3 Barrier Retrofitting Design Methodology
  • 6.3.1 Design Procedure
  • 6.3.2 Determine Ideal Barrier Performance Level
  • 6.3.3 Evaluate the Existing Bridge Structure
  • 6.3.4 Rationalisation of Barrier Performance Level
  • 6.3.5 Design Methodology
  • 6.4 Determination of Appropriate Barrier Performance Level
  • 6.4.1 Site-specific Risk Assessment
  • 6.4.2 Benefit-cost Analysis
  • 6.4.3 Additional Considerations
  • 6.5 Barrier Retrofit Design Procedure
  • 6.5.1 Characteristics of the Bridge Location
  • 6.5.2 Design for Upgrading Existing Barriers
  • 6.5.3 Design for Replacement of Existing Barrier
  • 6.5.4 Retrofitting Existing Structure
  • 6.5.5 Design of Connections
  • 6.5.6 Retrofitting of Bridge Approach Barriers
  • 6.6 Bridge Barrier Upgrade Exceptions
  • 6.7 Special Considerations for Historic Bridges
7 Bridge Approach Barriers
  • 7.1 Introduction
  • 7.2 Current Design and Specification Requirements
  • 7.2.1 Terminology
  • 7.2.2 Current AS 5100 Requirements
  • 7.2.3 Additional Requirements from Jurisdictions’ Guidelines
  • 7.3 Design Procedure
  • 7.4 Determination of Length of Need
  • 7.4.1 Run-out Length Method
  • 7.4.2 Angle of Departure Method
  • 7.5 Selection of Barrier Performance Level
  • 7.5.1 Methodology
  • 7.5.2 Performance Level and Associated Length Required to Contain Errant Vehicles
  • 7.5.3 Considerations to Preventing Errant Vehicles Entering High Risk Areas behind Approach Barriers
  • 7.5.4 Considerations Relevant to Minimum Lengths of Different Performance Level Bridge Approach Barriers
  • 7.5.5 Methodology for Determining Performance Levels and Associated Length of Median Bridge Approach Barrier Systems
  • 7.6 Typical Layouts
  • 7.7 Transition Between Different Performance Level Barriers
  • 7.7.1 General
  • 7.7.2 Design Criteria – Physically Connected Barriers
  • 7.7.3 Typical Interfaces Between Barrier Types
  • 7.8 End Treatments
  • 7.9 Gore Area
  • 7.10 Freeway and Highway Ramps and Side Roads
  • 7.11 Bridge Approach Off-structure Barrier Foundation
  • 7.12 Examples of Approach Barrier
  • 7.12.1 Example 1: Bridge Approach Barrier Layout Design
8 Bridge Support Protection Barriers
  • 8.1 Introduction
  • 8.2 Current Design and Specification Requirements
  • 8.2.1 Current AS 5100 Requirements
  • 8.2.2 Additional Requirements from Jurisdictions’ Guidelines
  • 8.3 Design Procedure
  • 8.4 Determination of Level of Protection
  • 8.4.1 Levels of Protection
  • 8.4.2 Risk Assessment
  • 8.4.3 Selection of Performance Level
  • 8.5 Barrier Layout and Design
  • 8.5.1 Length of Need
  • 8.5.2 Dynamic Deflection
  • 8.5.3 Vehicle Roll Allowance
  • 8.5.4 Typical Barrier Layout for Bridge Supports Adjacent to Undivided Roadways
  • 8.5.5 Typical Barrier Layout for Bridge Supports Located in Median Area
  • 8.5.6 Height Considerations
  • 8.5.7 Foundations for Rigid Barriers
  • 8.6 Bridge Support Protection from Railway Traffic
  • 8.7 Typical Design Drawings
  • 8.8 Examples
  • 8.8.1 Example 1: Protection Barrier for a Bridge Pier Adjacent to an Undivided Two-way Road
  • 8.8.2 Example 2: Protection Barrier for a Bridge Pier Located in a Median
9 Proposed Future Research
  • 9.1 Development of Detailed Standard Barrier Designs
  • Changes in test matrices
  • Changes in test vehicles
  • Changes of bridge barrier design loads in the revised AS 5100.2 (2004)
  • 9.2 Computer Simulation
  • 9.3 Safe System Approach
  • 9.4 Barrier Test Program
  • 9.5 Update to Austroads Guide to Bridge Technology
References
Appendix A Recommendations of 2006 Workshop
  • A.1 Background
  • A.2 Guest Speakers
  • A.3 Introduction
  • A.4 General Discussion Session
  • A.5 Summary
  • A.6 Recommendation
  • A.7 Bridge Barrier Issues Raised in the Workshop
Appendix B Meeting of Expert Group 2010
  • B.1 Present
  • B.2 Welcome and Introduction
  • ACTION: Nigel to follow up with Austroads Bridge Technical Review Panel on whether to include this as part of the project scope.
  • B.3 Role of the Group
  • Nigel
  • Gary
  • Expert group
  • B.4 Jurisdictional Expectations
  • VicRoads
  • RTA
  • DTEI
  • TMR
  • B.5 2010–11 Work
  • B.5.1 Consultation with Consultants and Contractors
  • B.5.2 AS 5100
  • B.5.3 Risk Assessment
  • B.5.4 Crash Study
  • B.6 2011–12 Work
  • B.6.1 Simulation Software
  • B.7 Some General Comment
  • B.8 Conclusion
Appendix C Comments from Consultants and Contractors
  • Worley Parsons
  • Parsons Brinkerhoff
  • ARUP
  • SMEC
  • GHD
Appendix D Expert Consultation
Appendix E BTTF Consultation
  • E.1 Section 3 – Selection of Bridge Barrier Performance Levels
  • E.1.1 Changes of Barrier Design Loads and Heights as a Result of MASH
  • E.1.2 The use of Site Categories and Number of Barrier Performance Levels
  • E.1.3 Criteria for Site Conditions and Specification Standards for CAT3 Method
  • E.2 Section 4 – Bridge Barrier Design Procedure
  • E.2.1 Capacity Reduction Factor, (
  • E.2.2 Jurisdictions’ Comments and Resolution
  • E.3 Section 5 – Standardised Bridge Barrier Designs
  • E.3.1 Directions in Selecting Existing Bridge Barrier Designs for Standardisation
  • E.3.2 Jurisdictions’ Comments and Resolution
  • E.4 Section 6 – Retrofitting of Existing Bridge Barriers
  • E.4.1 Points for Discussion
  • E.4.2 Jurisdictions’ Comments and Resolution
  • E.5 Section 7 – Bridge Approach Barriers
  • E.5.1 Points for Discussion
  • E.5.2 Jurisdictions’ Comments and Resolution
  • E.6 Section 8 – Bridge Support Protection Barriers
  • E.6.1 Points for Discussion
  • E.6.2 Jurisdictions’ Comments and Resolution

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