Description: A review has been made of the available information on the design and construction of large diameter thin-wall pipes to provide definitive guidance on the technical and economic merits of this form of construction. The information in this report is presented under four main areas. First, a critical review of the design methods in current use is made, with an explanation of the basis of application of the proposed method. Second, a description of the pipe materials available is given, together with the techniques employed for jointing and protection. The third topic is a guide to the procedures necessary to obtain backfill which meets design requirements. Finally an estimate is made of the relevant costs of different materials and the construction operations required in a completed pipeline. A section is also included on possible future research and development.