Sizing up the challenge

This paper describes three tunnels that have broken records in Norway, Turkey and China. The first is the #32M 7,765m long hard rock single bore Eiksundconnection road tunnel under the Vartdalsfjord in Norway. The deepest part of the tunnel will be nearly 300m below the fjord surface and the tunnel will reach the deepest ever sub-sea mark. The tunnel has a maximum gradient of 10%. Details are given of the drill and blast operations, the inclusion of polypropylene fibres in the sprayed concrete lining to minimise explosive spalling, and vehicle evacuation plans. The Chongming South Channel Tunnel is part of the 25km Shanghai-Chongming Expressway in China. The tunnel will be the largest ever bored tunnel. Tenders have been invited for the tunnel boring machines, which will work in soft estuarine silt. The twin bores will be crosslinked at regular intervals for evacuation. At 60m below sea level, the undersea section of the Marmaray rail tunnel across the Bosphorus in Turkey will be the deepest water in which an immersed tube tunnel will ever have been assembled. The immersed tube section is connected to conventional bored tunnels on land at each end. The challenges associated with constructing the tunnel are outlined.