Tuen Mun Chek Lap Kok Tunnel

The three mile-long Tuen Mun-Chek Lap Kok Link twin-tube tunnel will link the New Territories in the north to the artificial island of Hong Kong-Zhuhai-Macao Bridge Hong Kong Port, providing faster access to the international airport. The world’s largest slurry tunnel boring machine (with a diameter of 57.8 feet) was used to drive an initial 1968-feet-long section before being converted for the section of tunnel that narrows from three lanes to two. Once the shield and cutter head of the first TBM had been changed, two 46-feet diameter machines advanced within a high-pressure environment, excavating 2.6 miles of subsea tunnels. With excavating areas reaching up to 164 feet below sea level, maintenance operations were carried out in hyperbaric conditions, by teams of specialized divers living at the surface in pressurized habitats.