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Cover of Bridge Assessment Guideline: Heavy Vehicles
Bridge Assessment Guideline: Heavy Vehicles
  • Publication no: AP-G109-25
  • ISBN: 978-1-922994-89-9
  • Published: 11 September 2025
  • Edition: 1.0

The Bridge Assessment Guideline: Heavy Vehicles emphasises risk-informed decision-making for the asset management of road bridges and the management of heavy vehicle access. The emphasis on decision-making, rather than focussing only on the calculation of rating factors or assessment ratios, reflects the multitude of considerations faced by road agencies when making decisions concerning bridges.

The Guideline provides assessors and road agencies with a framework to reduce conservatism in the assessment of road bridges for heavy vehicle access, particularly for bridges that do not meet the requirements of AS 5100:2017, Bridge design, or the New Zealand Bridge manual. Where assessments indicate unsatisfactory performance despite in-field evidence to the contrary, the Guideline offers bridge-specific advice for explaining the plausibility check prescribed in ISO 13822:2010, Basis for design of structures –Assessment of existing structures, consistent with fundamental engineering principles.

In line with its focus on heavy vehicles, the Guideline provides advice and techniques for managing access by these vehicles over bridges. It distinguishes between bridge assessment, which is focused on structural performance, and heavy vehicle access management as related but distinct activities.

Watch a recording of the webinar to learn more.

  • Summary
  • Definitions
  • Abbreviations
  • 1. Introduction
    • 1.1 Guideline philosophy
    • 1.2 Background – need for Guideline
    • 1.3 Purpose and objectives
    • 1.4 Scope
    • 1.5 Context for bridge assessment
    • 1.6 Guideline approach to decision-making
    • 1.7 Guideline structure
  • 2. Assessment Fundamental Principles
    • 2.1 Introduction
    • 2.2 AS 5104 decision-making approaches
    • 2.3 Bayes’ Theorem
    • 2.4 Limit states
      • 2.4.1 Ultimate limit state assessment
      • 2.4.2 Serviceability limit state assessment
      • 2.4.3 Considerations for fatigue
      • 2.4.4 Limit state philosophy – heavy vehicles
    • 2.5 Engineering principles
      • 2.5.1 Plastic analyses
      • 2.5.2 Working stress method and limit states method
    • 2.6 Assumptions
    • 2.7 Observations
  • 3. Assessment Overview
    • 3.1 Introduction
    • 3.2 Qualifications and responsibilities
    • 3.3 Assessment flowchart
    • 3.4 Needs, scenarios, objectives and asset management context
    • 3.5 Preliminary assessment
    • 3.6 Detailed assessment
      • 3.6.1 Plausibility and past performance
    • 3.7 Results of assessment – documentation
      • 3.7.1 Documentation
  • 4. Risk-informed Decision-making
    • 4.1 Introduction
    • 4.2 ALARP and SFAIRP
    • 4.3 Risk identification
    • 4.4 Lessons from bridge failure/collapse
    • 4.5 Risk mitigation
    • 4.6 Systems behaviour and robustness
    • 4.7 Implementation in Guideline
  • 5. Reliability-based Decision-making
    • 5.1 Introduction
    • 5.2 Assumptions
    • 5.3 Background to reliability-based decision-making
    • 5.4 Target reliability indices
    • 5.5 Representative values of actions
    • 5.6 Site specific reliability analysis
    • 5.7 Calibration of Guideline
    • 5.8 Special heavy vehicles
  • 6. Semi-probabilistic Decision-making
    • 6.1 Introduction
    • 6.2 Data collection
    • 6.3 Inspection for assessment
    • 6.4 Material and section properties
    • 6.5 Actions not considered
    • 6.6 Permanent and time dependent actions
    • 6.7 Vehicle loads (reference vehicles)
    • 6.8 Preliminary risk assessment
      • 6.8.1 Risk considerations
      • 6.8.2 Target reliability indices
    • 6.9 Load factors
      • 6.9.1 Superimposed dead load factors
      • 6.9.2 Live load and dead load factors
    • 6.10 Analysis/modelling
      • 6.10.1 Introduction
      • 6.10.2 Line models and distribution factors
      • 6.10.3 Line model – design class
      • 6.10.4 Frame models
    • 6.11 Resistance
      • 6.11.1 Introduction
      • 6.11.2 Capacity reduction factors
      • 6.11.3 Concrete decks
      • 6.11.4 Shear in concrete – general
      • 6.11.5 Shear – modified compression field theory
      • 6.11.6 Strut-and-tie modelling
      • 6.11.7 Interface shear – concrete to concrete
      • 6.11.8 Interface shear – steel to concrete
      • 6.11.9 Development length for a deformed bar in tension
      • 6.11.10 Instability of slender concrete columns
      • 6.11.11 Fatigue resistance
      • 6.11.12 Geotechnical resistance
    • 6.12 Bridge assessment ratios
      • 6.12.1 Assessment ratios
      • 6.12.2 Adjusting assessment ratios
    • 6.13 Serviceability limit state check
    • 6.14 Plausibility check
  • 7. Refined Assessment – Plausibility Check
    • 7.1 Introduction
    • 7.2 Loads and materials
      • 7.2.1 Dynamic load allowance
      • 7.2.2 Live load model
      • 7.2.3 Dead loads
      • 7.2.4 Material properties
    • 7.3 Grillage and 3-dimensional frame analysis
    • 7.4 Plastic redistribution and elastic analysis
    • 7.5 Yield line analysis
      • 7.5.1 Introduction
      • 7.5.2 Background
      • 7.5.3 Principles for developing yield line patterns
      • 7.5.4 Assessment considerations
      • 7.5.5 Key references
    • 7.6 Concrete deck punching shear
    • 7.7 System behaviour
    • 7.8 Finite element analysis
  • 8. Bridge Specific Investigation
    • 8.1 Introduction
    • 8.2 Investigation planning
    • 8.3 Material testing
      • 8.3.1 Introduction
      • 8.3.2 Concrete
      • 8.3.3 Steel
    • 8.4 Dead load measurement
    • 8.5 Bridge specific live loading
      • 8.5.1 Introduction
      • 8.5.2 Data collection
      • 8.5.3 Statistical models
    • 8.6 Bridge response testing
    • 8.7 Proof load testing
      • 8.7.1 Introduction
      • 8.7.2 Proof load testing and structural reliability
      • 8.7.3 Proof load testing method
      • 8.7.4 Application of findings
      • 8.7.5 Further reading
    • 8.8 Characteristic value of a sample
    • 8.9 Bayesian updating
      • 8.9.1 Introduction
      • 8.9.2 Bayesian updating assuming hypothetical prior sample
      • 8.9.3 Updating characteristic material properties
      • 8.9.4 Updating live loading models
      • 8.9.5 Worked example for characteristic strength of concrete
    • 8.10 Updating bridge assessments
      • 8.10.1 Introduction
      • 8.10.2 Updating live load factors
      • 8.10.3 Updating using proof load testing
      • 8.11 Assessment by bridge type
  • 9. Judgement and Decision-Making
    • 9.1 Introduction
    • 9.2 Interpreting results
    • 9.3 Judgement and decision-making – asset
    • 9.4 Principles underpinning access
      • 9.4.1 Freight vehicles
      • 9.4.2 Special heavy vehicles
    • 9.5 Judgement and decision-making – access
      • 9.5.1 Introduction
      • 9.5.2 Current reliability based on past performance
      • 9.5.3 Reliable access for heavy vehicles
      • 9.5.4 Risk management for heavy vehicle access
    • 9.6 Potential consumption of assets
    • 9.7 Documentation and confirming assumptions
    • 9.8 Guideline examples
  • 10. Heavy Vehicle Access Management
    • 10.1 Introduction
    • 10.2 Application vehicles
    • 10.3 Access management methods
      • 10.3.1 Axle spacing mass schedules
      • 10.3.2 Lookup tables
      • 10.3.3 Line model comparisons
      • 10.3.4 Use of structural models
    • 10.4 Simply supported superstructures
    • 10.5 Superstructures continuous over supports
    • 10.6 Auditing and improvement
  • References
  • Appendix A Potential Assumptions for Assessment
  • Appendix B Reliability Background
    • B.1 Introduction
    • B.2 Assumptions for uncertainties
    • B.3 Summary of target reliability indices
    • B.4 Calibration principles
    • B.5 Mathematical relationships for random variables
    • B.6 Worked example using FOSM
    • B.7 Representative vehicles – freight
      • B.7.1 Representative vehicles – freight – Australian east coast
      • B.7.2 Representative vehicles – freight – Western Australia
      • B.7.3 Representative vehicles – freight – New Zealand
    • B.8 Representative vehicles – special heavy vehicles
      • B.8.1 Representative vehicles – indivisible mass – Eastern Australia
  • Appendix C Calibration of Guideline
    • C.1 Introduction
    • C.2 Target reliability index for AS 5100:2017
    • C.3 Calibration assumptions
    • C.4 Calibration using FOSM
    • C.5 Calibration check using FORM
    • C.6 Influence of DLA and AVF on calibration
    • C.7 Plausibility check
    • C.8 Serviceability limit state calibration
    • C.9 Canadian special heavy vehicle example
  • Appendix D Historical Material and Section Properties
    • D.1 Introduction
    • D.2 Concrete properties
    • D.3 Steel reinforcement properties
    • D.4 Prestressing strand properties
    • D.5 Prestressing bar properties
    • D.6 Steel beam properties
    • D.7 Wrought iron properties
    • D.8 Masonry properties
  • Appendix E Historical Design Classes
    • E.1 Introduction
    • E.2 Summary of design classes
    • E.3 1992 Austroads Bridge Design Code
      • E.3.1 General
      • E.3.2 T44 truck load
      • E.3.3 L44 lane load
      • E.3.4 Heavy load platform load
      • E.3.5 Number of lanes for design and lateral position of loads
      • E.3.6 Modification factors for multiple lane bridges
      • E.3.7 Design for localised load effects – W7 wheel load
      • E.3.8 Fatigue load
      • E.3.9 Load factors for design traffic loads
      • E.3.10 Dynamic load allowance
    • E.4 1976 NAASRA Bridge Design Specification
      • E.4.1 General
      • E.4.2 Standard vehicle load
      • E.4.3 Abnormal load
      • E.4.4 Minimum bridge loads
      • E.4.5 Standard design lanes
      • E.4.6 Reduction in load intensity in multiple lane bridges under standard vehicle load
      • E.4.7 Impact effects
      • E.4.8 Footway loading
    • E.5 1970 Highway Bridge Design Specification
      • E.5.1 General
      • E.5.2 Designation of loadings
      • E.5.3 M loadings
      • E.5.4 MS loadings
      • E.5.5 Classes of loadings
      • E.5.6 Minimum loadings
      • E.5.7 Overload provision
      • E.5.8 Design traffic lanes
      • E.5.9 Standard trucks and lane loads
      • E.5.10 Application of loadings
      • E.5.11 Reduction in load intensity
      • E.5.12 Moments, shears and reactions
      • E.5.13 Walkway loading
  • Appendix F Frame Models
    • F.1 Introduction
    • F.2 Modelling superstructures
      • F.2.1 Orientation of bearings on skewed bridges
    • F.3 Modelling substructures
      • F.3.1 Headstocks
      • F.3.2 Abutment walls
      • F.3.3 Spread footings
      • F.3.4 Piles
    • F.4 Modelling dead loads, creep and construction staging
    • F.5 Interpretation
      • F.5.1 Shear force diagrams
      • F.5.2 Bending moment diagrams
      • F.5.3 Limitations
    • F.6 Validation of models
    • F.7 Potential sources of modelling errors
      • F.7.1 Composite action between superstructure and headstock
      • F.7.2 Restrained longitudinal movement at bearings due to flexure
      • F.7.3 Longitudinal members of different depths
  • Appendix G Historical Concrete Shear Provisions
    • G.1 Introduction
    • G.2 Summary of Australian bridge design standards
  • Appendix H Overview of Shear in Concrete Members
    • H.1 Introduction
    • H.2 Kani tests
    • H.3 Theory predicts Kani tests
  • Appendix I Sectional Shear Resistance
    • I.1 Introduction
    • I.2 Notation
    • I.3 General
      • I.3.1 Regions requiring transverse reinforcement
      • I.3.2 Yield strength of prestressed transverse reinforcement
      • I.3.3 Variable-depth components
      • I.3.4 Reduced prestress within transfer length
    • I.4 Sectional assessment model
      • I.4.1 Preliminaries
      • I.4.2 Determination of Vc
      • I.4.3 Determination of Vs
      • I.4.4 Determination of kν and θν
      • I.4.5 Determination of εx
      • I.4.6 Transverse reinforcement area and spacing
      • I.4.7 Terminated longitudinal reinforcement in flexural tension zones
      • I.4.8 Transitions in transverse reinforcement
      • I.4.9 Extension of longitudinal reinforcement
      • I.4.10 Longitudinal reinforcement on the flexural tension side
      • I.4.11 Longitudinal reinforcement on the flexural compression side
      • I.4.12 Compression fan regions
      • I.4.13 Anchorage of longitudinal reinforcement at exterior supports
  • Appendix J Strut-and-Tie Modelling
    • J.1 Introduction
    • J.2 Background
    • J.3 Anchorage of reinforcement in strut-and-tie nodes
      • J.3.1 Introduction
      • J.3.2 Literature review
    • J.4 Bursting and crack control reinforcement
    • J.5 Strut-and-tie modelling and Kani test beams
  • Appendix K Assessment by Bridge Type
    • K.1 Reinforced concrete girder bridges
    • K.2 Prestressed concrete I girder bridges
    • K.3 Steel girder with composite concrete deck superstructures
    • K.4 Steel girder with timber deck superstructures
    • K.5 Prestressed concrete deck units with composite concrete deck superstructures
    • K.6 Prestressed concrete deck units with transverse post-tensioning
    • K.7 Superstructures continuous over supports
    • K.8 Reinforced concrete deck slab superstructures
    • K.9 Halving joints and steel pin and hangers
      • K.9.1 Concrete halving joints
      • K.9.2 Steel halving joints
      • K.9.3 Steel pin and hangers
    • K.10 Steel truss bridges
    • K.11 Timber bridges
    • K.12 Masonry arch bridges
    • K.13 Jack arch bridges
    • K.14 Substructures
      • K.14.1 General
      • K.14.2 Portal frames
      • K.14.3 Single columns with cantilevered headstocks
      • K.14.4 Pile caps
  • Appendix L Bridge Specific Live Loading Models
    • L.1 Data sources and attributes
    • L.2 Calibration of data collection systems
    • L.3 Data analysis
    • L.4 Updating live load factors
      • L.4.1 Background
      • L.4.2 Scaling factors for live load – kb, kV, kα
      • L.4.3 Live load factors for special heavy vehicles
      • L.4.4 Updating live load factors from BHV data
      • L.4.5 Final comments
  • Appendix M Worked Examples
    • M.1 Example 1 – assessment of pile caps
      • M.1.1 Needs, scenarios and objectives
      • M.1.2 Data collection
      • M.1.3 Inspection and observations
      • M.1.4 Vehicle loads (reference vehicles)
      • M.1.5 Preliminary risk assessment
      • M.1.6 Load factors
      • M.1.7 Analysis
      • M.1.8 Resistance calculations and assessment ratios
      • M.1.9 Refined assessment - plausibility check
      • M.1.10 Bridge specific investigations
      • M.1.11 Judgement and decision-making
      • M.1.12 Reporting and documentation
      • M.1.13 Final comments
    • M.2 Example 2 – updating an assessment using WiM data
      • M.2.1 Introduction
      • M.2.2 BSLL development for 15 m simply supported span from WiM data
      • M.2.3 Final comments
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