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Cover of Guide to Road Design Part 5: Drainage-General and Hydrology Considerations
Guide to Road Design Part 5: Drainage-General and Hydrology Considerations
  • Publication no: AGRD05-23
  • ISBN: 978-1-922700-76-6
  • Published: 30 January 2023
  • Edition: 4.0

Guide to Road Design Part 5: Drainage – General and Hydrology Considerations provides road designers and other practitioners with guidance on the design of drainage systems. This Guide needs to be used in conjunction with the other two Parts of the Guide to Road Design that relate to drainage design:

  • Part 5A: Drainage – Road Surface, Network, Basins and Subsurface
  • Part 5B: Drainage – Open Channels, Culverts and Floodway Crossings.

The estimation of rainfall and run-off is discussed together with other drainage design considerations. However, as this subject is extensive and covered in detail in other references, in particular the latest edition of Australian Rainfall and Runoff (ARR 2019), it is discussed in this Guide only to the extent necessary to support the design guidance provided.

This Guide provides information on the elements that need to be considered in the design of a drainage system including the hydrology, safety and environmental aspects, and the maintenance and operations of these systems.

The design processes and formulae necessary to design effective drainage systems and infrastructure are included. It is supported by appendices containing design charts and worked examples that provide further information.

This Guide outlines good practice in relation to drainage design that will apply in most situations, rather than specifying mandatory practice. The reason for this is that there are many factors that influence the design of a road and drainage for a particular situation or site, and practitioners therefore need to exercise sound judgement in applying the information contained in the Guide.

This latest update (Edition 4.0) to the Guide has focussed on incorporating the latest flow estimation techniques from ARR 2019. A part of the transition to ARR 2019 has been the change in terminology of rainfall design event likelihood from an Average Recurrence Interval (ARI) to an Annual Exceedance Probability (AEP). It was the intention of this latest Edition to completely update all references to ARI across to the equivalent AEP, however it was found there were so many references to ARI (including being embedded in figures) this could not be accommodated. A future update will tidy up all legacy references to ARI.

Edition 4.0 incorporates the latest flow estimation techniques from Australian Rainfall and Runoff released in 2019.

  • Summary
  • 1. Introduction
    • 1.1 Purpose
    • 1.2 Scope and Definitions
      • 1.2.1 Scope
      • 1.2.2 Definitions of Key Terms
    • 1.3 Jurisdictional Considerations
      • 1.3.1 Link to Jurisdictional Supplements
      • 1.3.2 Road Agency Policies and Guidelines
      • 1.3.3 Federal and State Legislation, Strategies and Guidelines
      • 1.3.4 Jurisdictional Responsibility
    • 1.4 Inter-agency Relations
    • 1.5 Management and Planning Framework
    • 1.6 Principles and Objectives of Drainage
      • 1.6.1 Principles
      • 1.6.2 Objectives
    • 1.7 Geometry and Drainage Relationship
    • 1.8 Use of Software
      • 1.8.1 Validation of Software and Predetermined Criteria
  • 2. Safety in Design
    • 2.1 Safe System
      • 2.1.1 Providing for a Safe System
    • 2.2 Workplace Health and Safety Act and Standards
    • 2.3 Life and Property
    • 2.4 Road Safety
    • 2.5 On-road Safety
      • 2.5.1 Protection for On-road Users
      • 2.5.2 Floodways
      • 2.5.3 Aquaplaning
      • 2.5.4 Cyclists
      • 2.5.5 Pit Lids
    • 2.6 Off-road Safety
      • 2.6.1 Pedestrians and Cyclists
      • 2.6.2 Maintenance Access
    • 2.7 Protection of General Public
      • 2.7.1 Culverts and Stormwater Drains
      • 2.7.2 Energy Dissipators
      • 2.7.3 Drainage Basins
      • 2.7.4 Fencing
  • 3. Environment
    • 3.1 General
      • 3.1.1 Scope
      • 3.1.2 Environmental Considerations
    • 3.2 Climate Change
      • 3.2.1 Introduction and Overview
      • 3.2.2 Risk Based Design Procedure
      • 3.2.3 Changes in Rainfall
      • 3.2.4 ARR Data Hub Output for Climate Change Factor
      • 3.2.5 Changes in Sea Level
      • 3.2.6 Climate Change Design Guide
      • 3.2.7 Infrastructure Sustainability Council of Australia (ISCA) IS Rating Scheme
    • 3.3 Fauna Passage/Crossings
      • 3.3.1 General
      • 3.3.2 Identifying Fauna Passage Criteria
      • 3.3.3 Identify Terrestrial and Aquatic Fauna Pathways
      • 3.3.4 Identify the Species Group
      • 3.3.5 Consult with the Relevant Authority
      • 3.3.6 Identify Criteria Affecting Drainage Design
      • 3.3.7 Fish Passage
      • 3.3.8 Fauna Crossings – Design Criteria
      • 3.3.9 Riparian and Wildlife Corridors
    • 3.4 Pollution Control and Water Quality
      • 3.4.1 General
      • 3.4.2 Sources of Pollution from Roads
      • 3.4.3 Spill Management
      • 3.4.4 Typical Steps for Pollution Control and Treatment
      • 3.4.5 At-source vs Catchment-based Treatment for Roads
      • 3.4.6 Debris Control
    • 3.5 Water Sensitive Design
      • 3.5.1 Urban Stormwater Management Principles
      • 3.5.2 Water Sensitive Urban/Road Design
      • 3.5.3 What is Best Practice?
      • 3.5.4 Performance Objectives
      • 3.5.5 MUSIC Model
      • 3.5.6 Key Design References
      • 3.5.7 Selecting Treatment Elements
      • 3.5.8 Bio-retention Systems
      • 3.5.9 Wetlands
      • 3.5.10 Treatment Train
      • 3.5.11 Maintenance and Disposal
    • 3.6 Erosion and Sediment
      • 3.6.1 General
      • 3.6.2 Scour
      • 3.6.3 Erosion Estimates
      • 3.6.4 Erosion and Scour Protection Measures
      • 3.6.5 Rock Protection
      • 3.6.6 Gabions
      • 3.6.7 Rock Mattresses
      • 3.6.8 Geotextiles
      • 3.6.9 Ground Cover
      • 3.6.10 Energy Dissipators
      • 3.6.11 Minimum Energy Loss Structures
      • 3.6.12 Sediment Transport
      • 3.6.13 Managing Sediment within Culverts
      • 3.6.14 Installation of Control Measures
      • 3.6.15 Maintenance of Control Measures
      • 3.6.16 Removal of Temporary Control Measures
    • 3.7 Blockage
      • 3.7.1 Procedure
    • 3.8 Miscellaneous
      • 3.8.1 Backwater
      • 3.8.2 Tidal Waters
      • 3.8.3 Storm Surge
      • 3.8.4 Downstream Tributary
      • 3.8.5 Tail Water Levels
      • 3.8.6 Acid Sulphate Soils
      • 3.8.7 Roadside Stops
      • 3.8.8 Water Harvesting
      • 3.8.9 Drainage Shadow
  • 4. Drainage Considerations
    • 4.1 General Considerations
      • 4.1.1 Australian Rainfall and Run-off (ARR)
    • 4.2 Road User Considerations
    • 4.3 Design Considerations
      • 4.3.1 Identifying Design Considerations
    • 4.4 Selection of Recurrence Interval and Flood Immunity
    • 4.5 Defining Immunity
      • 4.5.1 Flood Immunity
      • 4.5.2 Trafficability
      • 4.5.3 Time of Submergence/Closure
    • 4.6 Freeboard
      • 4.6.1 Kerbed Drainage
      • 4.6.2 Underground Piped Networks
      • 4.6.3 Drainage Basins
      • 4.6.4 Vertical Controls – Flood and Groundwater Levels
      • 4.6.5 Open Channel Design
      • 4.6.6 Culvert Design
    • 4.7 Other Considerations
      • 4.7.1 Drainage Construction Materials
      • 4.7.2 Recycled Materials
      • 4.7.3 Road Assets
      • 4.7.4 Groundwater
      • 4.7.5 Self-cleaning Sections
    • 4.8 Extreme Events
      • 4.8.1 Extreme Event Data Collection and Site Assessment
      • 4.8.2 Planning and Design
      • 4.8.3 Impacts of Extreme Events on Erodible Soil Environments
      • 4.8.4 Very Rare and Extreme Events
      • 4.8.5 Earthquake-prone Areas
    • 4.9 Waterway Structures
      • 4.9.1 Factors Affecting Selection of Waterway Structure
      • 4.9.2 Bridges – General
      • 4.9.3 Drainage of Bridge Decks
      • 4.9.4 Bridge Location and Waterway Alignment
      • 4.9.5 Bridge Geometry
  • 5. Operations and Maintenance
    • 5.1 Maintenance Access and Location
    • 5.2 Operation
      • 5.2.1 Period of Inspection
      • 5.2.2 Performance
    • 5.3 Maintenance
      • 5.3.1 Maintenance Process
      • 5.3.2 Types of Maintenance
    • 5.4 Drainage Failures
      • 5.4.1 Causes of Failure
      • 5.4.2 Types of Failure
      • 5.4.3 Environmental Impacts of Failures
      • 5.4.4 Identifying Failures
      • 5.4.5 Reporting of Failures
    • 5.5 Remediation
      • 5.5.1 Introduction
      • 5.5.2 Remediation Options
      • 5.5.3 Evaluation
  • 6. Hydrology
    • 6.1 Introduction
    • 6.2 Terminology
    • 6.3 Catchment Hydrology
      • 6.3.1 Introduction
      • 6.3.2 Catchment Properties
    • 6.4 Probability and Risk
      • 6.4.1 Introduction
      • 6.4.2 Probability and Risk Concepts for Road Design
      • 6.4.3 Probability Versus Risk Based Design
      • 6.4.4 Flood Immunity for Roads
      • 6.4.5 Flood Immunity for Pedestrian, Bicycle and Shared Paths
      • 6.4.6 Example Application of Flood Immunity Considerations
    • 6.5 Data for Drainage Design
      • 6.5.1 Introduction
      • 6.5.2 Categories of Data
      • 6.5.3 Data Management
      • 6.5.4 Rainfall Data
      • 6.5.5 Water Levels
      • 6.5.6 Streamflow Data
      • 6.5.7 Catchment Data
      • 6.5.8 Project Data
      • 6.5.9 Environmental Data
      • 6.5.10 Field Investigations and Site Inspections
      • 6.5.11 Sources of Data in Australia
    • 6.6 Hydrology Methods for Road Drainage and Flood Design
      • 6.6.1 Introduction
      • 6.6.2 Overview of Methods
      • 6.6.3 Description and Application of Recommended Methods
      • 6.6.4 Recommended Methods Comparisons
    • 6.7 Design Inputs
      • 6.7.1 Introduction
      • 6.7.2 ARR Data Hub
      • 6.7.3 Design Rainfall
      • 6.7.4 Areal Reduction Factors
      • 6.7.5 Temporal Patterns
      • 6.7.6 Specialist Analysis
      • 6.7.7 Design Loss
      • 6.7.8 Baseflow
      • 6.7.9 Recommended Methods for Specific Road Design Applications
    • 6.8 Design Software
      • 6.8.1 Introduction
      • 6.8.2 Hydrology
      • 6.8.3 Hydraulics
      • 6.8.4 Design
    • 6.9 Very Rare and Extreme Events
      • 6.9.1 Introduction
      • 6.9.2 Issues for Road Design
      • 6.9.3 Definition of Very Rare and Extreme Events
      • 6.9.4 Analysis Methods
    • 6.10 Specific Design Issues
      • 6.10.1 Flood Impact Criteria
      • 6.10.2 Flooding for Tunnel Portals
    • 6.11 Safety in Design
      • 6.11.1 Introduction
      • 6.11.2 Safety on Flooded Roads
      • 6.11.3 Risk with Drainage Infrastructure
    • 6.12 Joint Probability
      • 6.12.1 Introduction
      • 6.12.2 Joint probability Considerations in Hydrology
      • 6.12.3 Joint probability Considerations in Road Flood Design
      • 6.12.4 Flooding on a Road Link
    • 6.13 Uncertainty
      • 6.13.1 Introduction
      • 6.13.2 Sources of Uncertainty
      • 6.13.3 Examples of Uncertainty in Flood Design
      • 6.13.4 Application of Uncertainty in Road Design
  • References
  • Appendix A Design of an Infiltration Basin
    • A.1 Design of an Infiltration Basin
  • Appendix B Drainage Construction Material Considerations
  • Appendix C Summary of Erosion and Sedimentation Control Techniques
  • Appendix D Rational Method Background and Application
    • D.1 Method for Run-off Calculation
      • D.1.1 Rational Method
      • D.1.2 Applicability of Rational Method
    • D.2 Rural Hydrology
      • D.2.1 Rational Method
      • D.2.2 Time of Concentration
      • D.2.3 Run-off Coefficient
      • D.2.4 Partial Area Effects
      • D.2.5 Progressive Catchments
    • D.3 Urban Hydrology
      • D.3.1 Rational Method
      • D.3.2 Time of Concentration
      • D.3.4 Partial Area Effects
    • D.4 Worked Example (Rural): Rural Run-off
      • D.4.1 Catchment data
      • D.4.2 Solution
    • D.5 Worked Examples (Urban): Urban Run-off
      • D.5.1 Overland Flow Time
      • D.5.2 Use of Rational Method
  • Appendix E Estimation of Coefficient of Run-off – Queensland Application
    • E.1 Rural Hydrology
    • E.2 Urban Hydrology
  • Appendix F Estimation of Discharge from Rural Catchments in Victoria – Use of Area Size Factor
    • F.1 General
    • F.2 Victorian Conditions
    • F.3 Storm Run-off Estimation
    • F.4 Average Recurrence Interval
    • F.5 Definition of Catchment Area
    • F.6 Calculation of Characteristic Time
    • F.7 Average Rainfall Intensity
    • F.8 Design Discharge Factor
  • Appendix G Blockage Form
Related publications
Guide to Road Design Part 5A: Drainage: Road Surface, Networks, Basins and Subsurface
AGRD05A-23
Guide to Road Design Part 5B: Drainage-Open Channels, Culverts and Floodway Crossings
AGRD05B-23
View all related publications
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