The Ahmed Hamdi Tunnel provides a crossing under the Suez Canal for motor vehicles. It was originally constructed as a shield tunnel by the British government in 1983. It is 1.63 km long and has an outside diameter of 11.6 m.

Leakage of salt water through the reinforced concrete lining of the Ahmed Hamdi Tunnel was discovered very soon after construction was completed. The salty water quickly corroded the steel and degraded the concrete, leading to serious deterioration of the tunnel lining.

In 1992 construction commenced on a Japanese government grant aid project to rehabilitate the tunnel. NCC and Nippon Koei formed a joint venture and were engaged by the Japanese government to provide the engineering consulting services for the project. Our joint venture thoroughly investigated the deteriorated tunnel lining, determined the appropriate rehabilitation method, prepared the design, supervised construction, and introduced monitoring and maintenance systems.

The design called for first installing a 2 mm-thick waterproof sheet along the inside of the existing tunnel lining as a barrier to water. A sump pump drainage system was installed in the base of the tunnel to dispose of accumulated water. A secondary reinforced concrete tunnel lining was then constructed inside the original one, with the waterproof sheeting sandwiched in between. The secondary lining was designed to be structurally independent of the existing tunnel segments.