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
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.