AGRD04B Guide to road design part 4 Transport engineering PDF

Preview

Summary

AGRD04B Guide to road design part 4 Transport engineering, AGRD04B Guide to road design part 4 Transport engineering, AGRD04B Guide to road design part 4 Transport engineering...

Description

For Educational Purposes Only - RMIT University Library, Bundoora West Campus

For Educational Purposes Only - RMIT University Library, Bundoora West Campus

Guide to Road Design Part 4B: Roundabouts

Sydney 2015

For Educational Purposes Only - RMIT University Library, Bundoora West Campus Guide to Road Design Part 4B: Roundabouts Third edition project manager: Mike Whitehead Third edition prepared by: Peter Aumann

Publisher Austroads Ltd. Level 9, 287 Elizabeth Street Sydney NSW 2000 Australia

Third edition published December 2015

Phone: +61 2 8265 3300

Second edition published January 2011, First edition published August 2009

[email protected] www.austroads.com.au

This third edition 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. ISBN 978-1-925294-84-2 Austroads Project No. TP1718 Austroads Publication No. AGRD04B-15

Pages 84

© Austroads Ltd 2015 This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without the prior written permission of Austroads.

About Austroads Austroads’ purpose is to: • promote improved Australian and New Zealand transport outcomes • provide expert technical input to national policy development on road and road transport issues • promote improved practice and capability by road agencies. • promote consistency in road and road agency operations. Austroads membership comprises: • Roads and Maritime Services New South Wales • Roads Corporation Victoria • Department of Transport and Main Roads Queensland • Main Roads Western Australia • Department of Planning, Transport and Infrastructure South Australia • Department of State Growth Tasmania • Department of Transport Northern Territory • Territory and Municipal Services Directorate, Australian Capital Territory • Commonwealth Department of Infrastructure and Regional Development • Australian Local Government Association • New Zealand Transport Agency. The success of Austroads is derived from the collaboration of member organisations and others in the road industry. It aims to be the Australasian leader in providing high quality information, advice and fostering research in the road transport sector.

Abstract 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 4B also provides information on pedestrian and cyclist treatment at roundabouts and related topics such as pavement markings, signs and landscaping. However, designers should refer to other relevant parts of the Guide to Road Design and to the Guide to Traffic Management Part 6: Intersections, Interchanges and Crossings (Austroads 2013a) that cover traffic management and road use aspects of roundabouts and criteria for the appropriate selection and design of intersections. It will be necessary for designers to refer to other parts of the Guide to Road Design for guidance on general criteria and information that are common to all at-grade intersections, in particular: Part 4: Intersections and Crossings – General (Austroads 2009a) and Part 4A: Unsignalised and Signalised Intersections (Austroads 2010a). Keywords Design principles, design procedure, sight distance, geometric design, central island, entry geometry, circulating carriageway, superelevation, gradient, central island radius, pedestrians, cyclists, bicycle lanes, bicycle paths, shared paths, landscaping. This Guide is produced by Austroads as a general guide. Its application is discretionary. Road authorities may vary their practice according to local circumstances and policies. Austroads believes this publication to be correct at the time of printing and does not accept responsibility for any consequences arising from the use of information herein. Readers should rely on their own skill and judgement to apply information to particular issues.

For Educational Purposes Only - RMIT University Library, Bundoora West Campus Acknowledgements The authors acknowledge the role and contribution of the Austroads Road Design Task Force in providing guidance and information during the preparation of this Guide. The panel comprised the following members: Mr Peter Ellis

Roads and Maritime Services New South Wales

Mr Richard Fanning

Roads Corporation Victoria

Mr Mike Whitehead

Department of Transport and Main Roads, Queensland (Project Manager)

Mr Albert Wong

Main Roads Western Australia

Mr Noel O’Callaghan

Department of Planning, Transport and Infrastructure South Australia

Mr William Moodie

Department of Transport Northern Territory

Mr Ben McHugh

Territory and Municipal Services Directorate, Australian Capital Territory

Mr Tony Napoli

Australian Local Government Association

Mr James Hughes

NZ Transport Agency

Mr Tom Brock

Consult Australia

Ms Gemma Kernich

Australian Bicycle Council

Mr Michael Tziotis

ARRB Group Ltd.

It is also acknowledged that this third edition has been updated from previous editions prepared by Gary Veith and Owen Arndt.

For Educational Purposes Only - RMIT University Library, Bundoora West Campus Guide to Road Design Part 4B: Roundabouts

Contents 1. 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9

Introduction............................................................................................................................................. 1 Purpose .................................................................................................................................................... 1 Scope of this Part ..................................................................................................................................... 1 Road Safety .............................................................................................................................................. 2 Road Design Objectives ........................................................................................................................... 3 Traffic Management at Roundabouts ....................................................................................................... 3 Safety Performance of Roundabouts .......................................................................................................3 Traffic Capacity of Roundabouts .............................................................................................................. 5 Signalisation of Roundabouts................................................................................................................... 5 Roundabouts in High speed Rural Areas ................................................................................................. 6

2. 2.1 2.2 2.3

Design Principles and Procedure ......................................................................................................... 7 Terminology .............................................................................................................................................. 7 Design Principles ...................................................................................................................................... 8 Design Procedure ..................................................................................................................................... 8

3. 3.1 3.2

Sight Distance.......................................................................................................................................12 Introduction ............................................................................................................................................. 12 Sight Distance Criteria ............................................................................................................................ 12 3.2.1 Criterion 1 ................................................................................................................................. 12 3.2.2 Criterion 2 ................................................................................................................................. 14 3.2.3 Criterion 3 ................................................................................................................................. 15 3.2.4 Other Visibility Considerations.................................................................................................. 15 Stopping Sight Distance for Trucks ........................................................................................................15

3.3 4. 4.1 4.2 4.3

4.4

4.5

4.6

4.7 4.8 4.9

Geometric Design .................................................................................................................................16 Introduction ............................................................................................................................................. 16 Number of Legs ......................................................................................................................................16 Number of Entry, Circulating and Exit Lanes ......................................................................................... 16 4.3.1 Introduction ............................................................................................................................... 16 4.3.2 Number of Entry Lanes ............................................................................................................. 16 4.3.3 Number of Circulating Lanes .................................................................................................... 17 4.3.4 Number of Exit Lanes ............................................................................................................... 17 4.3.5 Left-turn Slip Lanes .................................................................................................................. 17 4.3.6 Special Use Lanes .................................................................................................................... 17 Central Island ......................................................................................................................................... 18 4.4.1 Central Island Shape ................................................................................................................ 18 4.4.2 Factors Affecting Central Island Size ....................................................................................... 19 4.4.3 Central Island Radius ............................................................................................................... 19 Approach and Entry Geometry ...............................................................................................................21 4.5.1 General ..................................................................................................................................... 21 4.5.2 Approach and Entry Treatments............................................................................................... 22 4.5.3 Maximum Entry Path Radius .................................................................................................... 26 4.5.4 Splitter Islands .......................................................................................................................... 30 Circulating Carriageway ......................................................................................................................... 31 4.6.1 Design Vehicle and Vehicle Swept Paths ................................................................................ 31 4.6.2 Width of Circulating Carriageway ............................................................................................. 31 4.6.3 Encroachment Areas ................................................................................................................ 36 Exit Curves ............................................................................................................................................. 38 Entry and Exit Widths ............................................................................................................................. 38 Separation between Legs ....................................................................................................................... 39

Austroads 2015 | page i

For Educational Purposes Only - RMIT University Library, Bundoora West Campus Guide to Road Design Part 4B: Roundabouts

4.10 Superelevation, Gradient and Drainage .................................................................................................42 4.10.1 Crossfall .................................................................................................................................... 42 4.10.2 Approach Grade ....................................................................................................................... 44 4.10.3 Drainage ................................................................................................................................... 44 4.11 Special Treatments................................................................................................................................. 45 4.11.1 Wide Medians and Streets of Unequal Width........................................................................... 45 4.11.2 Wide Undivided Streets and T-intersections ............................................................................ 46 5. 5.1 5.2

5.3

Pedestrian and Cyclist Treatments .................................................................................................... 47 Introduction ............................................................................................................................................. 47 Pedestrians .............................................................................................................................................47 5.2.1 Safety Analysis of Roundabouts for Pedestrians ..................................................................... 47 5.2.2 Designing Roundabouts for Pedestrians .................................................................................. 47 Cyclists ................................................................................................................................................... 49 5.3.1 Introduction ............................................................................................................................... 49 5.3.2 Safety Analysis of Roundabouts for Cyclists ............................................................................ 49 5.3.3 Designing Roundabouts for Cyclists ........................................................................................ 49 5.3.4 Roads with Shared Traffic ........................................................................................................ 50 5.3.5 Multi-lane Roundabouts............................................................................................................ 51 5.3.6 Bicycle Paths and Shared Paths at Roundabouts.................................................................... 51 5.3.7 Other Considerations ................................................................................................................ 52

6. 6.1 6.2 6.3

Pavement Markings and Signing ........................................................................................................ 53 Introduction ............................................................................................................................................. 53 Single-lane Local Street Roundabout ....................................................................................................54 Multi-lane Arterial Road Roundabout ..................................................................................................... 54

7. 7.1 7.2 7.3 7.4

Landscaping and Street Furniture ...................................................................................................... 56 Introduction ............................................................................................................................................. 56 Arterial Road Roundabouts .................................................................................................................... 56 Local Street Roundabouts ...................................................................................................................... 58 Maintenance ........................................................................................................................................... 59

References ......................................................................................................................................................60 Crash Types ............................................................................................................................. 62 Roundabout Study and Program ........................................................................................... 65 Methods of Improving Roundabout Entries .........................................................................66 Linemarking of Multi-Lane Roundabouts .............................................................................71 Extended Design Domain (EDD) for Entry Path Radii ......................................................... 78

Austroads 2015 | page ii

For Educational Purposes Only - RMIT University Library, Bundoora West Campus Guide to Road Design Part 4B: Roundabouts

Tables Table 2.1: Table 3.1: Table 4.1: Table 4.2: Table 4.3: Table 4.4: Table 6.1:

Design procedure – considerations and cross-references ........................................................ 10 Criterion 2 sight distances ......................................................................................................... 14 Guide for selecting the minimum central island radius for a circular roundabout .....................20 Maximum entry path radii for one and two-lane roundabouts ................................................... 26 Initial selection of single-lane roundabout circulating carriageway widths ...............