The Shatin to Central Link (SCL) extends the Hong Kong metro lines "Ma On Shan Line" and "East Rail Line" and connects the "West Rail Line". These strategic east-west (EWC) and north-south (NSC) corridors fill gaps in the overall Hong Kong metro network. For the further development of the port city, in the densely built-up urban center there is no way around mechanized tunnelling. A Herrenknecht Mixshield and a Variable Density TBM bored around 7 kilometer of tunnels for the EWC. The NSC project included construction of a new metro station in the vibrant metropolis near the Hong Kong Convention and Exhibition Center. Three additional Herrenknecht Mixshields dug the associated four tunnel passages totaling a good 2 kilometer in length.
East West Corridor
The two EWC tubes driven with mechanized tunnelling start parallel at the Causeway Bay Typhoon Shelter and dock one above the other at the new Exhibition Station. For this first tunnel section, a Mixshield dug its way through the underground of Hong Kong. The second section leads from the Convention Avenue / Fenwick Pier Street construction site to Admiralty Station. A Variable Density TBM was used for this very sensitive drive near the coastline through mixed geologies with overburdens of partly only about 6 meters. The innovative machine concept combines the advantages of EPB and Mixshield technology and allows a flexible response to geological and hydrogeological changes along the alignment.
North South Corridor
For the NSC, a Mixshield built two 1,700 meter long tunnels through granite between the Ma Chai Hang Ventilation Building and Diamond Hill. In Wong Tai Sin district, the alignment passes under tall buildings. Two more Mixshields were also used. In heterogeneous soils they excavated the 1,600 meter long twin tubes between To Kwa Wan and Ho Man Tin Station.
The site crews successfully crossed under all areas without affecting the existing buildings. In November 2017, with the final breakthrough of the last TBM on the EWC, all tunnelling for the Shatin to Central Link was completed.