The DTL tunnels to the station had to be constructed right above the operational East West line (EWL) tunnels. To minimise any upward movement of the EWL tunnels, cement was pumped into the soft soil to strengthen it, while structures such as hydraulic jacks and interlocking pipes were installed above the tunnels. The steel pipes for the DTL tunnels' foundation had to be cautiously positioned to avoid any damage to the EWL tunnels. To address the poor ground conditions at the site during excavation, the diaphragm walls adopted the “Trouser Legs” concept which allowed the walls to reach the harder soil at deeper depths, functioning as both as earth–retaining and foundation elements.
