The first of the two 12.34m diameter double shield gripper TBMs that will be driving the twin tunnels of the Brisbane North-South bypass was set to be launched this month.
Excavation on the project continues to run ahead of the original programme, which was given a boost by early site access enabling rapid shaft sinking. The original schedule for completion of the toll link was October 2010 and it is estimated that the new transport link could open in late 2009.
Part of the 4.8km long drive for each Herrenknecht machine passes under the Brisbane River and there is also possibly a fault to face. The programme lead provides contingency should there be difficulties with the crossing.
The first TBM is driving the northbound tube and will take about a year to complete the bore, the second machine is scheduled to launch early in 2008 having just recently arrived in Australia after being shipped from Germany.
Concessionaire RiverCity Motorway is building the 6.8km long twin tube toll link. Geology consists principally of tuff (80MPa-150MPa) and cover of 6m-30m.
The contractor is LBB JV, which includes Leighton Contractors, Baulderstone Hornibrook and Bilfinger Berger. The TBM-driven, segmentally lined tunnels were designed by Bilfinger. Principal design for the scheme is by a JV of Maunsell and Parsons Brinckerhoff.
Construction on the project began in August 2006 and early this year the first roadheaders began to carve out a total of 3km of access tunnels. The roadheaders have about another year of work to do. At least seven roadheaders will be used on the project.
