Papers drawn from the quarterly Civil Engineering journal of ICE Proceedings Editor Simon Fullalove, tel: +44 20 7665 2448 fax: +44 20 7538 9620 email: simon. fullalove@ice. org. uk Secretary Agnes Alvite, tel: +44 20 7665 2242 email: agnes. alvite@ice. org. uk Production manager Zoe Holland Civil Engineering Panel Honorary Editor Mike Thorn, Wallingford Research Consultancy, UK Daniel Anstice, Maunsell, UK Andrew Baldwin, Loughborough University of Technology, UK Suzanna Caccavone, Binnie Black & Veatch, UK Cathal Langan, Allot & Lomax, UK Kenny O'Hara, Scott Wilson Scotland, UK.
Jeremy Lumbers, Tynemarch Systems Engineering Sara Parkin, Forum for the Future, UK Mike Salter WSP Development John Perry, University of Birmingham, UK Alastair Scott, BG Exploration & Production Mike Winney, New Civil Engineer, Emap Construct, UK All ICE Proceedings papers published since 1837 are indexed by the ICE Library on the ICE website at www. ice. org. uk. Copies can be posted or faxed to members for a fee. Summaries of papers from 1998 are freely available on the website and subscribers can download full versions.
copyright The authors and the Institution of Civil Engineers, 2002.
All rights, including translation, reserved. Except for fair copying, 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, recording or otherwise, without the prior written per ion of the Author and the publisher. Requests should be directed to the Publisher, Journals, Thomas Telford Ltd.
Papers or other contributions and the statements made or opinions expressed therein are published on the understanding that the author of the contribution is solely responsible for the 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 ICE Council or ICE Committees.
Illustrations by Anthea and Ben Carter Design and layout by Kneath Associates, Swansea