The Central-Wanchai Bypass is a new immersed tunnel design which will be laid on top of existing MTR Tsuen Wan Line (TWL). The design combines five separate box structures of the original design into one single structure, 120 metres long, 47 wide and 10 high. The structure is supported on two rows of bored piles along each side of the TWL tunnel. The design permits the tunnel installation to be carried out in one phase and substantially reduces the impact on marine traffic in the Victoria Harbour and the risk of damage to the TWL. The structure which using Everdure Caltite System concrete will be precast in a dry dock in China close to Hong Kong waters from where it will be towed to the site and ballasted with seawater to sink it onto the bored pile supports. In order to minimize the impact on the existing MTR Tsuen Wan Line immersed tube tunnel, the section of the CWB across the MTR Tsuen Wan Line would be constructed in form of a piled deck structure spanned over the MTR Tunnel.