ABSTRACT
This paper describes the design and operation of sinking techniques for concrete caissons under compressed air to form access shafts to the sewer tunnels of Contract 4 of the Greater Cairo Wastewater Project. The contractor’s rationale for the control of risk, and the benefits obtained by the development of shaft access equipment to improve both safety and productivity are described. The contractor’s experience with the technique is outlined and some details of the safety record achieved in compressed air working are given. The paper is presented from the viewpoint of design consultants appointed by the contractor, Lilley-Misr Group, to develop and detail their conceptual proposals for the construction techniques adopted.
