Longer stretches of soft ground have enabled the second drive of the Kowloon Southern Link tunnel, in Hong Kong, to be completed faster by the 7.99m diameter Herrenknecht slurry TBM and hole through in early March.
The challenge of the second, 1.17km long drive saw it weave below streets, then over and beside the first tunnel, further complicated at times by being only one diameter or less below the surface.
Further challenges on the second drive included crossing above two metro tunnels with approximately 1.7m clearance, and 2m below a box culvert that is connected to the harbour. Also, there was only 6.4m of cover beneath a major road intersection.
The TBM was re-launched for the second drive in late September last year. It had holed through on the first drive in late June after being launched in November 2006.
Originally, it was anticipated that the twin tunnels would be completed by January this year and in the third quarter last year, prior to the launch of the second drive, the client said that the final breakthrough was then expected to be this month, which has been achieved.
The first drive had its own challenges, in particular a brief setback when there was compressed air loss and some ground settlement below Salisbury Road on, fortunately, the quiet early hours in the weekend. The TBM had been stationary for a compressed air intervention.
The drives have been completed by contractor Link200 JV, members of which are Leighton Contractors (Asia), Balfour Beatty, Kumagai and John Holland. Link200 JV’s US$258M contract is one part of the US$1.06bn project to hook-up the East and West metro lines.
Client for the project is now Mass Transit Railway Corp (MTRC), which took on the project as part of its takeover of Kowloon Canton Railway Corp (KCRC) last year.
The 7.99m diameter Herrenknecht Mixshield breaks through in Hong Kong
