Tunnelling to the top
And the spotlight should be shining bright on Brisbane; after all, the world's largest hard-rock double shield tunnel boring machine (TBM) has just landed on their doorstep.
After an eight-week journey, the star of the North-South Bypass tunnel arrived at the Port of Brisbane in late September, set to start work in December – three months ahead of schedule.
Following its early manufacture at Herrenknecht's factory in Schwanau, there was a six-week dismantling process before the 3800-tonne TBM could be loaded on to trucks to transport it to a barge at Kehl.
From there, a four-day trip along the Rhine River to the Rotterdam Port where it was finally loaded on to a freight ship headed for Australia.
The route to Australia from Germany was via the Gulf of Mexico, through the Panama Canal and across the Pacific, finally landing at the Port of Brisbane.
Skelton Tomkinson (the freight forwarding division of Skelton Group responsible for the TBM delivery) was faced with a further logistical challenge as it rushed to source a specialised vessel from the United States that was capable of both the heavy lift and increased knots the project required to meet early delivery deadlines.
"This project has been all about meeting strict deadlines from the beginning," Brad Skelton, managing director of the Skelton Group said.
"The RiverCity Consortium promised a tunnel built faster than anyone else and Skelton's played an integral role in ensuring all the heavy equipment and TBMs were here as expediently as possible.
"Most people wouldn't believe the planning that needs to go into such projects. But we've had our team on the ground in Germany while the TBM was being built to oversee the dismantling, loading and European land-sea component of the journey.
"Since then, we've been focussed on securing the various permits and certifications, coordinating the Skelton Trucking fleet for the haulage and working with the LBBJV (Leighton Contractors and Baulderstone Hornibrook Bilfinger Berger Joint Venture) project team to organise the delivery and assemblage of the TBM."
Skelton said the company will be responsible for unloading the TBM and transporting it across the Gateway Motorway to its final destination at Bowen Hills, where it will be reassembled onsite.
Skelton explained the plan to transport the TBM across the Gateway Bridge has also proved challenging with research into the bridge design to ensure it can manage the load.
"The Gateway Bridge is designed as an HLP620 which means it can carry 20 tonnes of line over 20 lines," he said.
"The largest Skelton Trucking load for the Brisbane tunnel project will be 17.5 tonnes of line over 14 lines – well within the Main Roads requirements."
Skelton said the project logistics team at Skelton Group also called for the entire Inner City Bypass to be independently surveyed by structural engineers to guarantee soundness.
Meanwhile, the Skelton Trucking trailers were inspected by an automotive engineer to certify the hydraulics could evenly spread the weight across the 25m of trailer.
The geometrics of the trailers have also been certified by mechanical engineers in accordance with the route the TBM will travel, thus making sure nothing is too wide or high on the road.
Skelton Group was also responsible for bringing in six of the seven road headers for the tunnel as part of the logistics management contract which it holds for all RiverCity projects through to 2010.
The road headers started excavation in February 2007, two months ahead of schedule.
In total some 3.5 million tonnes of rock is expected to be removed to make way for Brisbane's first major road tunnel comprising twin tunnels, 4.1km and 4.3km in length.
Most of the work will be left to two Herrenknecht hard-rock double-shield TBMs, with seven roadheaders being used for the remaining works, comprising two Mitsui S300s, four Paurat T3.20Q and one Voest-Alpine AM150.
The manufacture of the second TBM is three months ahead of schedule, with plans for this machine to start excavation in March 2008.
RiverCity Motorway chief executive officer Flan Cleary said Herrenknecht double-shield technology was chosen because fault zones are likely to be encountered in the medium to hard rock conditions - which include tuff, arenite and quartz-phyllite formations.
"By selecting double-shield machines we are able to excavate rock and place the concrete tunnel lining at the same time," he said.
Cleary said the plan is for each machine to start on the north side of the Brisbane River at Bowen Hills and travel south, finishing at Woolloongabba.
"The task ahead of them is enormous when you consider that we will be excavating enough rock to fill the Brisbane Cricket Ground nine times over," he said.
"With a 12.4-metre diameter cutting head, equivalent to a four-storey building, and a body that is 250 metres long, these machines truly are tunnelling juggernauts."
The works will take a team of 21 people per shift to operate each TBM 24 hours a day, six days a week, inside purpose-built acoustic sheds, with expected advancements of up to 20m per day. Contract completion for the tunnel is due in October 2010.
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