Manual on the Use of Timber in Coastal and River Engineering

Manual on the use of timber in coastal and river engineering Matt Crossman Jonathan Simm Published by Thomas Telford Publishing, Thomas Telford Ltd, 1 Heron Quay, London E14 4JD. URL: http://www.thomastelford.com Distributors for Thomas Telford books are USA: ASCE Press, 1801 Alexander Bell Drive, Reston, VA 20191-4400, USA Japan: Maruzen Co. Ltd, Book Department, 3–10 Nihonbashi 2-chome, Chuo-ku, Tokyo 103 Australia: DA Books and Journals, 648 Whitehorse Road, Mitcham 3132, Victoria First published 2004 Cover photograph Pile extensions (courtesy Arun District Council) A catalogue record for this book is available from the British Library ISBN: 0 7277 3283 8 © Queen’s Printer and Controller of Her Majesty’s Stationery Office and HR Wallingford Ltd, 2004. This work is not subject to the terms of the Class Licence for the reproduction of Crown copyright material. All rights, including translation, reserved. Except as permitted by the Copyright, Designs and Patents Act 1988, no part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying or otherwise, without the prior written permission of the Publishing Director, Thomas Telford Publishing, Thomas Telford Ltd, 1 Heron Quay, London E14 4JD. This book is published on the understanding that the authors are solely responsible for the statements made and opinions expressed in it and that its publication does not necessarily imply that such statements and/or opinions are or reflect the views or opinions of the publishers. While every effort has been made to ensure that the statements made and the opinions expressed in this publication provide a safe and accurate guide, no liability or responsibility can be accepted in this respect by the authors or publishers. Typeset by HR Wallingford Ltd Printed and bound in Great Britain by MPG Books, Bodmin, Cornwall This report also constitutes the joint Defra/Environment Agency Flood & Coastal Erosion Risk Management Research & Development Programme Publication W5A – 069. Preface This document is intended to provide information and guidance on the use of timber in coastal, maritime and river engineering projects. Timber has traditionally been used for the construction of a wide variety of engineering structures in or near water including groynes, jetties, lock gates and river bank protection. The fact that it is still used for many of these applications, despite advances in alternative materials is, at least partially, a reflection of the generally accepted characteristics that make timber an attractive choice of construction material. These are: x renewable resource x high strength to weight ratio x high tolerance of impact and short duration loads x good resistance to abrasion x ease of construction, on site repairs and recycling x attractive appearance x natural durability (to a greater or lesser extent). However, there are also a number of potential drawbacks including: x inherent flaws and variability in properties associated with all natural materials x limited availability of the very large section sizes, long lengths or high durability required for some engineering purposes x species of timber native to the UK are only moderately resistant to the marine environment and are susceptible to biological hazards x most species used in engineering applications are only renewable over a relatively long timescale, making it difficult to demonstrate sustainability, and few sources of tropical hardwoods are currently certified. As a renewable resource, timber has the potential to be an environmentally responsible choice of material, particularly if recycled or obtained from sustainably managed forests. Although it is the only renewable construction material, negative publicity surrounding logging, particularly of tropical forests, has resulted in some reluctance from engineers to exploit the practical, environmental and aesthetic advantages of timber and there is an increasing reliance on alternative materials. Timber also needs different design and construction techniques from those used for materials such as concrete and steel. There has been some concern that the knowledge of experienced engineers is being lost as they retire and the skills required to use timber efficiently and effectively are not being passed on to younger engineers. This manual addresses these issues by providing an introduction to the use and properties of timber, a framework for responsible selection and procurement of timber materials (including recycled timber), and a discussion of design and construction issues. Different types of timber structures are documented, and management and maintenance practices are described. iii MANUAL ON THE USE OF TIMBER IN COASTAL AND RIVER ENGINEERING The manual is intended for practising engineers and may also be a useful reference for students, procurement specialists and managers wishing to understand more about the use of timber in coastal and river environments. iv Acknowledgements This manual has been prepared as the primary deliverable from an HR Wallingford research project carried out under the Department of Trade and Industry ‘Partners in Innovation’ scheme. (N.B. The Contract was started under the Department of the Environment, Transport and the Regions, and transferred to the Department of Trade and Industry during financial year 2001/2). The objective of the research was to collate existing knowledge, experience and research in order to develop best practice guidance on the use of timber in coastal and river engineering. The manual was prepared by HR Wallingford and published on behalf of the Department of Trade and Industry and the Environment Agency. The views and information presented are those of HR Wallingford and whilst they reflect the consensus of the Steering Group, they are not necessarily those of the funding organisations. The project was managed by Matt Crossman under the guidance of Jonathan Simm of HR Wallingford. The manual was edited by Matt Crossman and Jonathan Simm from text prepared by John Williams, Simon Howard, John Roach, Rod Nelson, Jeremy Purseglove, Brian Holland, Udo Perdok and David Harlow. Additional editorial support was provided by Clive Orbell- Durrant and Celia Yardley. Further information on some of the issues explored within this manual is provided on the associated website at: www.timbermanual.org Project funders Cash funding for the project was provided by the following organisations: x Department of Trade and Industry (Partners in Innovation programme) x Environment Agency x HR Wallingford x TRADA Technology x British Waterways x SCOPAC. In kind contributions In kind contributions, including data, staff time and other resources committed to the project were provided by the following organisations: x Aitken & Howard Ltd x The Institution of Civil Engineers x Arun District Council x John Martin Construction x Babtie Group x Mackley Construction x Bournemouth Borough Council x Mott MacDonald x British Waterways x Mowlem x Dean and Dyball x Posford Haskoning x Ecosylva x SCOPAC x Environment Agency x Shoreham Port v MANUAL ON THE USE OF TIMBER IN COASTAL AND RIVER ENGINEERING x GR Wiltshire & Co. x TRADA Technology x HR Wallingford x WS Atkins Steering Group The research was guided by a steering group comprising the following members: John Andrews Posford Haskoning Peter Anidjar-Romain WS Atkins Rob Bentinck Mowlem Marine David Bligh British Waterways Andrew Bradbury SCOPAC Mark Buttle GR Wiltshire & Co. Tony Camilleri Mackley Construction Richard Copas Environment Agency Matt Crossman HR Wallingford David Harlow Bournemouth Borough Council Mike Hodgson John Martin Construction Brian Holland Arun District Council Simon Howard Posford Haskoning Paul Kemp Aitken & Howard Ltd John Laker Dean & Dyball Construction Rod Nelson Ecosylva Clive Orbell-Durrant Independent Consultant Tony Parker Posford Haskoning Jeremy Purseglove Mott MacDonald John Roach Babtie Group Jonathan Simm (Chairman) HR Wallingford Tony Vaughan Shoreham Port Authority Brian Waters Institution of Civil Engineers John Williams TRADA Technology Assistance was also received from: Martin Luker Environment Agency Stephen McFarland Canterbury City Council Stephen Cook New Forest District Council Maaike van der Kroon HAS Den Bosch Udo Perdok TU-Delft Henk Jan Verhagen TU-Delft Wim Bak Rijkswaterstaat HR Wallingford are grateful to the funders, the Steering Group and all those who have contributed time and information to the project. Particular thanks are due to Udo Perdok who made a substantial contribution to the success of the project whilst at Wallingford as part of his MSc at Delft University of Technology. We would also like to thank Maaike van der Kroon for her input to the environmental issues, Bev Reader for her organisational and administrative assistance and those involved in the finalisation of the document, including vi ACKNOWLEDGEMENTS Clive Orbett-Durrent, Celia Kirby, Mike Wallis and the staff of HR Wallingford’s Report Production Unit. HR Wallingford carries out advanced research, consultancy and software development relating to civil engineering hydraulics and the water environment. Established in 1947 as a Government research centre, it is now an independent not-for-profit company employing over 200 engineers, scientists, mathematicians and support staff. HR Wallingford is concerned with all aspects of water management and engineering in catchments, rivers, estuaries, coasts and offshore. It carries out predictive physical

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