Auckland calls for rail link proposals 04 Oct 2018

TunnelTalk Reporting

Proposals have been called from two shortlisted tenderers for construction of the Contract 3 stations and tunnels for the City Rail Link project in Auckland. The two groups competing for the competitive alliance procurement contract are:

  • Downer New Zealand, Vinci Construction, Soletanche Bachy, with engineers AECOM, Tonkin & Taylor, WSP Opus
  • CPB Contractors, UGL (NZ), and engineers Beca, McMillen Jacobs and Jacobs New Zealand

Fig 1. Route of the new underground railway line
Fig 1. Route of the new underground railway line
Procurement contracts for the project
Procurement contracts for the project

The request for proposals phase, started in early September, is programmed to be completed by February 2019 with a contract award by the end of March 2019. A portion of the bid costs for any unsuccessful shortlisted bidder will be paid in return for any intellectual property rights and effort expended.  

Contract 3 of the new underground rail line for the city comprises about 3.4km of 7m diameter twin bored running tunnels to link two underground stations at Aotea and Karangahape with a grade separated junction within mined caverns to connect with two cut-and-cover tunnels to form a connection with the existing North Auckland rail line at the existing Mt Eden Station (Fig 1). Aotea station will be constructed in a 300m long cut-and-cover box to about 15m deep and the Karangahape Station will be a mined station at about 32m deep comprising two platform caverns and a concourse cavern leading to escalators and lifts to the surface (Fig 2).

Fig 2. Topography of the new line
Fig 2. Topography of the new line
Design of mined caverns for Karangahape Station
Design of mined caverns for Karangahape Station

Construction work on the underground rail project started in 2016 with award of the first two and most challenging contracts located at the city centre end of the line where the existing Britomart station must be converted from its current terminus configuration to a through station. When complete the new line will create a loop link from the current Britomart terminus station to the North Auckland rail line at Mt Eden Station (Fig 3). Providing through-trail rail access into the heart of the city will significantly increase passenger access to the city and change fundamentally public rail transport into and around Auckland.

Under advanced works contracts Britomart Station has been completely trans-configured from a five-platform terminus station to a two-terminus platforms plus two through-train platforms station. Under Contract 1, awarded to the Downer NZ / Soletanche Bachy JV in 2016, two cut-and-cover rail tunnels are being constructed directly under Auckland’s iconic and historic Chief Post Office building which was built and opened in 1912 and today houses the Britmart Transport Centre and station ticket hall and concourse. Alternative access has been provided while the Post Office building is closed temporarily to allow for major construction works in its basements. To start work, the Category 1 listed heritage building has had to be underpinned. Working over the past two years, this underpinning process has been completed and the building has now been load transferred onto the temporary foundations, with the steel underpinning frame now taking the weight of the eastern façade.

Fig 3. New line will create a through link from the current terminus station at Britomart in the city centre to the North Auckland rail line at Mt Eden Station
Fig 3. New line will create a through link from the current terminus station at Britomart in the city centre to the North Auckland rail line at Mt Eden Station

Work has continued with excavation of a 14m deep trench that will contain the project’s twin rail tunnels under Britomart Station and Lower Queen Street to provide access to start excavating the two running tunnels under the Post Office building from Lower Queen Street. Box excavation is scheduled to be finished by mid-2019, after which time the trench will be backfilled, Lower Queen Street reinstated and the Post Office building rebuilt with basement and ground floor levels.

Meanwhile, the Connectus JV of McConnell Dowell and Downer, has been advancing a length of tunnel of open cut work along Albert Street. This work will connect eventually to open cut tunnels being built under the neighbouring Commercial Bay development and on to Britomart Station and at the opposite end to the TBM running tunnel alignment at Aotea Station. Fletcher Construction is working on the cut and cover alignment for the rail link through the Precinct area of downtown and the Commercial Bay development.

Funded jointly by the New Zealand Government and the Auckland City Council, the 3.45km twin-track underground City Rail Link is the largest infrastructure project ever undertaken in New Zealand and is on track to be completed in 2024.

           

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