Road design

Cover of Guide to Road Design Part 4B: Roundabouts
Guide to Road Design Part 4B: Roundabouts
  • Publication no: AGRD04B-15
  • ISBN: 978-1-925294-84-2
  • Published: 8 December 2015
  • Edition: 3

The Guide to Road Design Part 4B: Roundabouts provides road designers and other practitioners with guidance on the geometric design of roundabouts. It covers design principles and procedures, and guidelines for all the key elements, thus enabling practitioners to develop safe and efficient layouts.

Part 4Balso provides information on pedestrian and cyclist treatment at roundabouts and related topics such as pavement markings, signs and landscaping.

Designers should also refer to:

  • Guide to Road Design Part 4: Intersections and Crossings – General
  • Guide to Road Design Part 4A: Unsignalised and Signalised Intersections
  • Guide to Traffic Management Part 6: Intersections, Interchanges and Crossings

Edition 3.0 of the Guide contains technical changes and minor editorial changes to Sections 1.3, 1.6, 1.9, 4.3, 4.4, 4.5, 4.7, 4.9, 5.3, 6.3, and 7 and the addition of information relating to the extended design domain for vehicle entry path radii. Updates have been made throughout this edition to include new and updated reference material and cross-references added to other Guides, including:

  • Section 1 Introduction: updates to road safety including Safe System; additional information relating to motorcycles; and Section 1.9 deleted and replaced with information on roundabouts in high-speed areas.
  • Section 4 Geometric Design: additional information on entry, circulating and exit lanes; additional information on the central island radius and amendment to Table 4.1; amended information on approach treatments; amended Table 4.2 – Maximum entry path radii; additional information on exit curves; additional information of the separation of the roundabout legs.
  • Section 5 Pedestrian and Cyclist Treatments: information on bicycles at roundabouts amended, including deletion of commentary and figures relating to bicycle lanes within roundabouts.
  • Section 6 Pavement Markings and Signing: amended information on the use of spiral linemarking.
  • Section 7 Roadway Lighting at Roundabouts: deleted.
  • Appendix E Extended Design Domain for Entry Path Radii: new