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Road Design

Cover of Bicycle Safety at Roundabouts
Bicycle Safety at Roundabouts
  • Publication no: AP-R542-17
  • ISBN: 978-1-925451-66-5
  • Published: 1 May 2017

This report investigates how the geometric design components of a roundabout may contribute to bicycle crashes.

An Australian and New Zealand crash analysis found that most of the crashes occurred at urban local road roundabouts, in 50 km/h speed limit zones. The crashes predominantly occurred on the circulating lane near the entry for an approach road and were right-adjacent type crashes.

The study included an in-depth investigation of 17 roundabouts across Queensland, New South Wales and Victoria. A geometric analysis identified that the entry geometry of the roundabouts investigated would permit relatively high entry speeds, in excess of the target speed of less than 30 km/h. This target speed was adopted for analysis purposes, however, further investigation to determine an appropriate speed to prevent or minimise fatal and serious injury outcomes for crashes involving motor vehicle and cyclists is needed.

The motor vehicle speeds on the entry and circulating lanes were estimated using the ARNDT crash prediction model, however the model was developed on rural roads and so the application of this model to urban local roads requires verification. For the purposes of this investigation, the ARNDT model was used to assess geometric alignments to achieve lower approach speeds and it was found that a roundabout with a radial-type of alignment, used in countries in Europe, achieved approach and circulating speeds of less than 30 km/h.

Sight distances were examined and it was found that the available sight distance to vehicles approaching from the right did not meet the design requirements. There is some research which indicates that restricting the sight distance on the approach to a roundabout reduces the approach speeds of vehicles, however, this requires further investigation to develop design criteria.

The report recommends further investigation into motor vehicle/cyclist crash outcomes and the effect of restricting sight distance on the approaches to a roundabout, and the development of design guidance for urban local road roundabouts.

  • Summary
  • 1. Introduction
    • 1.1. Background
    • 1.2. Objectives
    • 1.3. Methodology
      • 1.3.1. Establishment of a Project Advisory Group
      • 1.3.2. Literature Review
      • 1.3.3. Crash Analysis
      • 1.3.4. Investigation of Selected Roundabouts in Queensland, New South Wales and Victoria
      • 1.3.5. Workshop
      • 1.3.6. Final Report
  • 2. Literature Review
    • 2.1. Types of Roundabouts
    • 2.2. Design Principles
      • 2.2.1. Australia and New Zealand
      • 2.2.2. United Kingdom
      • 2.2.3. Netherlands
      • 2.2.4. Germany
      • 2.2.5. United States of America
      • 2.2.6. Summary
    • 2.3. Current Practices for Cyclists at Roundabouts
      • 2.3.1. Australia and New Zealand
      • 2.3.2. United Kingdom
      • 2.3.3. Netherlands
      • 2.3.4. Denmark
      • 2.3.5. Germany
      • 2.3.6. United States of America
      • 2.3.7. Canada
    • 2.4. Additional Risk Factors
    • 2.5. Summary
  • 3. Geometric Design Practices
    • 3.1. Geometric Components
      • 3.1.1. Design Vehicles
      • 3.1.2. Entry Geometry
      • 3.1.3. Entry Width
      • 3.1.4. Central Island and Circulating Carriageway
      • 3.1.5. Exit Geometry
      • 3.1.6. Sight Distance
      • 3.1.7. Summary
  • 4. Crashes at Roundabouts
    • 4.1. Australia and New Zealand
    • 4.2. Denmark
    • 4.3. Germany
  • 5. Crash Data Analysis
    • 5.1. Crashes by Year, Month, Day and Time
    • 5.2. Crashes by Type and Severity
    • 5.3. Crashes by Light, Surface and Atmospheric Conditions
    • 5.4. Speed Zones
    • 5.5. Crashes by Demographics
    • 5.6. Crashes by Vehicle Type
    • 5.7. Data Limitations
      • 5.7.1. Crash Numbers in Queensland
      • 5.7.2. ‘At Fault’ and Error Statistics – South Australia
      • 5.7.3. Potential Contributing Factors to Crashes – New Zealand
      • 5.7.4. Helmet Conditions – Victoria and Queensland
    • 5.8. Summary and Interpretation of Results
  • 6. Sites with High Crash Numbers
    • 6.1. Roundabout Locations
      • 6.1.1. Victorian Sites
      • 6.1.2. New South Wales Sites
      • 6.1.3. Queensland Sites
    • 6.2. Roundabouts on High Speed Roads
    • 6.3. Summary
    • 6.4. Site Selection
      • 6.4.1. Methodology
      • 6.4.2. Crash Diagrams
      • 6.4.3. Geometric Information
      • 6.4.4. Field Investigations
      • 6.4.5. Traffic Data
    • 6.5. Contributing Factors
      • 6.5.1. Sight Distance
      • 6.5.2. Vehicle Speeds
      • 6.5.3. Lane Widths
    • 6.6. Selection of Countermeasures
  • 7. Geometric Analysis
    • 7.1. Vehicle Speed Assessment
    • 7.2. Detailed Investigations
      • 7.2.1. Eastern Avenue – Tresidder Avenue, Kingsford
      • 7.2.2. Drummond Street – Pigdon Street, Carlton
      • 7.2.3. Barnstaple Road – Ingham Avenue, Five Dock
      • 7.2.4. Heffron Road – Banks Avenue, Pagewood
      • 7.2.5. Monbulk Road – Kallista-Emerald Road, Kallista
      • 7.2.6. Bowen Crescent – Garton Street, Carlton
      • 7.2.7. Union Street – Upton Road, Windsor
      • 7.2.8. Seaworld Drive – Waterways Drive, Main Beach
      • 7.2.9. Anzac Parade – Rainbow Street, Kingsford
      • 7.2.10. Phillip Street – Young Street, Redfern
      • 7.2.11. Old Burleigh Road – Queensland Avenue, Broadbeach
      • 7.2.12. Gilbert Road – Henty Street, Reservoir
      • 7.2.13. Oriel Road – Banksia Street, Heidelberg
      • 7.2.14. Childs Road – Dalton Road, Mill Park
      • 7.2.15. Cotlew Street – Wardoo Street, Ashmore
      • 7.2.16. Whittlesea Road – Arthurs Creek Road, Yan Yean
      • 7.2.17. Helensvale Road – Hope Island Road, Hope Island
  • 8. Possible Treatments
    • 8.1. Single-lane Roundabouts
      • 8.1.1. Approach Alignment
      • 8.1.2. Entry Path Curve Radius
      • 8.1.3. Entry Lane Width
      • 8.1.4. Central Island
      • 8.1.5. Vertical Displacement Treatments
      • 8.1.6. Sight Distance
      • 8.1.7. Geometric Information
    • 8.2. Single-lane Rural Arterial Road Roundabout
    • 8.3. Multilane Roundabouts
      • 8.3.1. C-roundabout
      • 8.3.2. Merge Zones
      • 8.3.3. Off-road Path Connection
    • 8.4. Conclusions
  • 9. Suggested Amendments to Austroads Guides
    • 9.1. Guide to Road Design
      • 9.1.1. Part 4B: Roundabouts
      • 9.1.2. Section 5.3: Cyclists
      • 9.1.3. Part 6A: Pedestrian and Cyclist Paths
    • 9.2. Guide to Traffic Management
      • 9.2.1. Part 6: Intersections Interchanges and Crossings
    • 9.3. Cycling Aspects of Austroads Guides
      • 9.3.1. Section 5.5: Roundabouts
    • 9.4. Other Recommendations
  • References
  • Appendix A Crash Data
  • A.1 Crashes by Year, Month, Day and Time
  • A.2 Crashes by Type and Severity
  • A.3 Crashes by Light, Surface and Atmospheric Conditions
  • A.4 Crashes by Speed Zones
  • A.5 Crashes by Demographics
  • A.6 Crashes by Road User Type
  • A.7 Crashes by Helmet Conditions
  • Appendix B Definitions for Coding Accidents
  • Appendix C Surveyed Roundabout Speeds
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