Brisbane City Council is inviting international tunnelling contractors to register to bid by April 29 for a 35 year concession to finance, design, build, operate, maintain and repair the US$771M, 5km North-South bypass tunnel.

The tunnel is the first phase of the TransApex tunnel network planned for the city by Lord Mayor Campbell Newman. The city council is hoping to prepare a shortlist of groups ready for bids to be invited by August.

Firms from Australia, China and Europe, including companies in Germany, France and Spain, have already indicated their interest following a meeting with council officials. Council officials expect the successful group to excavate the tunnel using tunnel boring machines, roadheaders and drill and blast techniques. Officials are confident the TBMs can excavate at rates up to 90m a week through hard rock at depths of up to 60m.

Three tunnel portals will be built at Bowen Hills, Kangaroo Point and Woolloongabba to facilitate tunnelling. Work involves building twin 12m diameter parallel tunnels, including a section under the Brisbane River, together with the installation of ventilation, fire protection and electronic tolling systems.

About 150 trucks a day will be used to remove about 2.45M m3 of muck generated by the project. Most of the material has been earmarked for the redevelopment of Brisbane airport and a second Gateway bridge.

The Queensland state government has agreed to provide an US$347M loan, although this is conditional on an agreement on tunnel tolls. Separately, the Brisbane cabinet has approved US$3.9M in funding for a US$19.3M prefeasbility study to extend the North-South tunnel by a further 5km from Bowen Hills to Brisbane Hills. The tunnel extension could open in 2012. Officials hope the Queensland government will provide most of the cash for the study, which will focus on tunnel alignments and traffic projections.