The Herrenknecht TBM excavating the Kowloon Southern Link in Hong Kong is being dismantled for transport back to the launch shaft in preparation for the second drive due to commence in September.

The 7.99m diameter slurry TBM holed through into the reception shaft to complete the 1.17km first bore at the end of June, having had a brief issue a few weeks earlier with compressed air loss and ground settlement in the road overhead.

Following the launch in November, the machine bored under Canton Road until the problem as it turned towards the home leg under Salisbury Road. The TBM has 2,400kW of cutterhead torque and can produce a total thrust of 53kN. The cutterhead weighs 105 tonnes and was the first section lifted out of the reception shaft in the dismantling.

The initial programme was for about six months for the excavation of each drive with the bores due to be completed in January 2008. The setback below Salisbury Road stopped work only briefly, but now the programme for the second drive anticipates completion in March next year, according to the client, Kowloon-Canton Railway Corporation (KCRC).

KCRC blamed the problem of 3 June below Salisbury Road on the loss of compressed air through a zone of unexpectedly weak soil in the generally weathered and fresh granite. A compressed air intervention was underway in the early hours of that Sunday morning when monitoring equipment alerted tunnellers of a suspected ground disturbance. KCRC confirmed it has submitted a report on the investigation into the problem to the government.

Being built under a US$258M contract by a the Link 200 JV that includes Leighton Contractors (Asia), Balfour Beatty, Kumagai and John Holland, the twin tube tunnel project is being built to link the East and West metro lines. Construction of the entire US$1.06bn main link project is due for completion in 2009.

The metros are not the only link-ups underway in Hong Kong as KCRC is currently joining with the Mass Transit Railway Corporation (MTRC).


The TBM breaks through on the first 1.17km long drive of the Kowloon Southern Link The TBM breaks through Aerial view of the site