Northern Link plan of attack
Northern Link plan of attack Sep 2010
Shani Wallis, TunnelTalk
The contract is yet to be signed, but Transcity is celebrating its selection last week as the consortium to design, build, operate and maintain Brisbane's new Northern Link highway tunnel.
Giovanni Giacomin, tunnelling director for consortium partner Ghella, told TunnelTalk that the consortium, with partners Acciona of Spain and local construction company BMD, had worked hard on the bid and were delighted at the result. "Seven groups prequalified, three were shortlisted and of the two bids submitted, ours is selected." He added that the tunnel is much the same in design as the Clem7 highway tunnel under the Brisbane River and that the steel structures of the two 12.4m diameter Herrenknecht TBMs used for that project will be used again on the Northern Link.
Pic 1

Take two for Clem7 TBMs

"The Northern Link tunnels are in the same geological formations as the Clem7 tunnels and it was obvious that the successful method under the river could be repeated on Northern Link," said Giacomin. "The Airport Link project, north of the city, is in a different formation and its TBMs are EPB machines." The Clem7 machines are double-shield TBMs with lateral grippers in the gripper shield to allow for simultaneous excavation and segment ring building.
"The predicted ground conditions are quite good," said Giacomin, who has worked on several major TBM tunnelling projects around the world before taking on the role as Director of Tunnelling for the privately owned contractor Ghella. "There is good site investigation information provided by the client and additional studies were conducted by the client and by us to gather more data."
TBM tunnelling is the principal excavation method and there are areas of drill+blast and roadheader excavation for equipment chambers, cross passages and on and off ramps. The consortium is to build its own segment fabrication yard for the TBM drives.
Lead engineers to the design-build consortium are GHD, URS, Cardno and RPS. Engineers with the second bid from Northern Direct JV of Bouygues, Laing O'Rourke and Transfield, were Arup, Mott MacDonald, Butler Partners and Douglas Partners. An honorarium of some $5 million is payable to the unsuccessful tenderer to purchase the intellectual property of the bid. This is "to ensure that we have the ability to take good ideas from unsuccessful bidders and apply them to the winning bid to make it an even better project," according to Brisbane City Mayor Campbell Newman, political champion of the four tunnel projects that will form an inner city ring road around Brisbane's CBD.
Like the Clem7, Airport Link, and Go-Between Bridge projects in the TransApex ring road programme, the Northern Link is a toll highway. However, unlike the others, the Brisbane City Council as the owner is arranging the financing and is taking the toll traffic risk. The Council has secured approval from the Queensland Government to borrow the necessary funds for the project and the Australian Federal Government has committed $500 million contribution. But given experience to date there is concern about the validity of the financing model, with a fear that property taxes will have to rise to cover any financial deficit.
Pic 1

TransApex tollway projects

As the first TransApex project to open in March this year, private operating company RiverCity Motorway has had to reduce the Clem7 toll dramatically. Traffic dropped from nearly 59,000/day when the tunnel opened free of charge, to about 21,000 when a toll of $4.28 each way was imposed a month later. The toll is now at $2 each way and traffic has increased to about 33,000/day but that is still far from the calculated 60,000 needed a day to keep construction loan interest payments paid and operating costs in the black.
The Go Between Bridge, built by the Bouygues-led consortium and opened in mid-year, has also nearly halved its toll from $2.70 to $1.50 to build traffic from about 9,000 per day at opening. Under the lower toll, traffic had increased to more than 11,500 per day in September towards a target of 12,800 per day by October.
TransApex tollway projects
Traffic forecasts for the Airport Link and its toll structure are also under scrutiny. For the Northern Link, the Council estimates about 24,000 vehicles per day when it opens in 2014, rising to about 48,800 per day by 2026. The Northern Link will open with a toll of $3 each way, rising to $4.61 the following year and by inflation per year thereafter.
Construction on the Aust$1.5-1.7 billion Northern Link project is expected to begin before the end of this year and be completed and in operation in 2014.
Brisbane awards Northern Link highway - TunnelTalk, September 2010

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