Tunnelling through a maze of existing tunnels and cables.Some of the special techniques (PDF) used include top-down construction (PDF, 648kb), and building a continuous bored pile wall (PDF, 475kb), a secant pile wall, and diaphragm (PDF, 371kb) and sheet pile walls (PDF, 372kb) (internal) (PDF, 243kb). In the Mountbatten area, hard ground made it extra difficult to extract some 500 reinforced concrete and steel foundation structures (called piles) that had been placed as supportive structures, and explosives had to be used to break through the rock. Special techniques were used to tunnel in these areas as well as under the Kallang Basin. Varying soil conditions, which posed safety and structural issues at both Promenade and Nicoll Highway MRT stations.The story of the CCL’s long journey is marked by hard work, tenacity and innovation to overcome numerous challenges, such as: Construction began in 2002, and the line came into operation in phases from 2009.
