First Herrenknecht TBM breaks through in Brisbane
10 August 2021One of two Herrenknecht TBMs mining the Cross River Rail tunnels in Brisbane, Australia has holed through into an underground cavern beneath Roma Street to complete a section of tunnel running below the Brisbane River and the CBD.
Since its launch from the Wooloongabba site in February 2021, TBM Else has worked 24/7, tunnelling a total of 2,580m through hard rock at an average rate of 20-30m/day, mining around 105,000m3 of spoil in the process. The second TBM ‘Merle’ is expected to arrive at Roma Street in the coming weeks.
At 7.2m in diameter, both machines will bore 3.8km of the total 5.9km of twin tunnels that will stretch from Wooloongabba to the project’s northern portal at Normanby where Else is expected to break through at the end of 2021. TBM Merle is expected to follow shortly after. Other stretches of tunnel (from Wooloongabba to Boggo Road) and station caverns are being excavated by two roadheaders which have so far mined around 650m each.
Both TBMs are noteworthy given they were refurbished and retrofitted at Herrenknecht’s Northside facility with back-up gantries that were repurposed from the Sydney Metro project. The cutterheads are armed with 39 cutting discs exerting a pressure of 32t each, and the machines have been lining the tunnels with 270mm x 1.7m precast concrete segments. At the deepest point, the tunnels will lie 58m below the surface at Kangaroo Point and 42m below the Brisbane River.
The 10.2km-long Cross River Rail line will have four new underground stations at Boggo Road, Albert Street, Roma Street and Woolloongabba. It is seen as having been a key factor in Brisbane securing the 2032 Olympic and Paralympic Games.
