Evaluation in urban and industrial environments: the Docklands Light Railway, Lewisham Extension, London

Abstract

Objectives This case history describes the use of information obtained from the initial desk-based engineering geological and geotechnical studies carried out as part of the design of civil engineering works for the Lewisham Extension of the Docklands Light Railway (DLR) which was constructed in a heavily developed urban environment. The desk study aimed to make best use of available information in order to evaluate the terrain, limit the need for further ground investigation and provide geological and geotechnical information to the design teams as quickly as possible. A desk study is an integral part of terrain and site evaluation and, wherever possible, should be carried out in conjunction with a reconnaissance survey (or walk-over) of the site. Together they are likely to be of greatest value and most cost-effective when carried out early in the investigations for a proposed development. They can provide the project team with an early indication of the conditions at the site, such information being essential for master planning and concept design. As the project is advanced the desk study findings become the basis for the planning and interpretation of the subsequent more expensive and lengthy stage of physical investigation by (for example) boreholes and trial pits. Conceptually, it should be self-evident that it is cheaper to obtain and evaluate information that already exists than to obtain new investigation data. But this is not the only reason for carrying out desk studies. Their ability to recover information that cannot be obtained by other means is also very