Boring starts on Shenzhen Underground, China

Two of the three NFM tunnel boring machines (TBM) being used to construct Line 3 of the Shenzhen Underground, in Shenzhen, Guangdong Province, China have begun excavation work.

The first TBM, which started work on 14 November, will carry out the 2.54 km of twin-tube tunnel between Hong Ling and Lao Jie stations. The second machine began service on 19 November and will bore 2.4 km of tunnel between Cui Zhu and Tian Bei stations.

The third machine should put its first loop into place in December 2008 before starting to bore 1.1 km between Tian Bei and Shui Bei.

The three 6.28 m diameter TBMs, which have been supplied by NFM Technologies, are earth pressure balance models designed to cope with the difficulties of unstable and water-logged ground conditions.

Shenzhen plans to expand its Underground system from the two lines currently in service to five lines between now and 2011. NFM Technologies will be providing a total of 12 6.28 m diameter earth pressure machines.

In addiction to the three TBMs for Line 3, one machine is currently being assembled on site for use on the extension of Line 2. Eight other machines, currently being factory assembled, should be delivered during 2009.