ABSTRACT
Singapore’s 30km-long all-underground Thomson Line (TSL) involves the operation of approximately thirty Tunnel Boring Machines (TBMs) to complete the twin tunnels and the construction of twenty-two underground stations, including five interchange stations. This involves challenges such as tunnelling in urbanized areas and poor geological conditions such as reclaimed land. Bored tunnels of 5.8m internal diameter are aligned in side-by-side or stacked configuration to accommodate these constraints. In addition to challenges posed by densely-urbanised landscape, the project runs through a number of interfaces, which necessitates tunnelling in close proximity to existing railway lines and stations, such as interface at Outram Park and Robinson Road. Another challenging construction contracts, T226, includes the construction of a portion of Marina Bay Station, a TBM launch shaft, two working shafts to facilitate the underpinning of live operational rail tunnels and station, mining of a pedestrian link directly underneath with clearance of 1.0m, as well as mined mainline tunnels.
