Road design
 Publication no: AGRD04A17
 ISBN: 9781925451733
 Published: 7 June 2017
 Edition: 3
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Guide to Road Design Part 4A: Unsignalised and Signalised Intersections provides road designers and other practitioners with guidance on the detailed geometric design of all atgrade intersections (excluding roundabouts).
This Part contains information for the design of signalised and unsignalised intersections. Guidance is provided on intersection sight distances, including approach sight distance, safe intersection sight distance, and minimum gap sight distance. Left and right turn treatments are outlined including the incorporation of auxiliary lanes at intersections and the use and size of traffic islands.
Edition 3.0 contains minor editorial and technical changes throughout the Guide, and substantial parts of Sections 1.4, 3.2, 4.34.14, 5.1, 5.2, 6.1, 7.17.5, 8, 9 and 10 have been transferred to Guide to Road Design Part 4: Intersections and Crossings – General.
Updates have been made throughout this edition to include new and updated reference material and crossâ€‘references to other Guides. Most figures have been redrawn to provide a consistent appearance. The major updates include:
 Section 1: Introduction: Updates to road safety, including the Safe System principles.
 Section 3: Sight Distance: Incorporates additional information relating to safe intersection sight distance and additional description in tables to assist in interpretation.
 Section 5: Auxiliary Lanes: Section 5.2 (new number), has information included from the commentaries on turning radii and vehicle speeds, and Table 5.4 contains additional information on acceleration lane lengths.
 Section 6: Traffic Islands and Medians: Information from Appendix D has been included in Section 6.2.







 Appendix A 2.1 Application of EDD for Sight Distance at Intersections
 Appendix A 2.2 Base and Check Cases
 Appendix A 2.3 EDD Approach Sight Distance (ASD)
 Appendix A 2.4 Observation Times for EDD Safe Intersection Sight Distance
 Appendix A 2.5 EDD Safe Intersection Sight Distance (SISD)
 Appendix A 2.6 Sight Distance at Constrained Urban Intersections

 Appendix A 5.1 Intent of EDD Turn Treatments
 Appendix A 5.2 Use of EDD Turn Treatments
 Appendix A 5.3 General Considerations
 Appendix A 5.4 Minimum EDD Channelised Rightturn Treatment for Twolane Twoway Roadways without Medians
 Appendix A 5.5 Minimum EDD Channelised Rightturn Treatment for Roadways with Medians
 Appendix A 5.6 Minimum EDD Auxiliary Leftturn Treatment


Tables

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