The infrastructure planners and contractors make huge efforts to keep pace with the city state's population and economic growth. The large-scale metro project "Circle Line" has a length of 33.3 kilometers. Shaped like a circle and with a total of 26 stations, the Circle Line runs once around downtown Singapore and connects all other metro lines.
Tunnel boring machines by Herrenknecht were used along eleven sections: nine EPB Shields and two Mixshields. The EPB Shields' working principles proved of value in Singapore's underground, characterized by a low permeability. The two Mixshields were employed on the three-kilometer-long section between One-North and Farrer Road. The last EPB Shield successfully completed its drive for the Circle Line in March 2009. In October 2011 the new line was put into operation.
