Auckland’s City Rail Link (CRL) has started excavating the 14m deep trench that will contain the project’s twin rail tunnels under Britomart Station and Lower Queen Street.
The excavation follows two years of careful preparation work to protect Britomart Station’s historic Chief Post Office (CPO) building and support the ground before the trenching and tunnel construction can begin.
CRL contractor Downer-Soletanche Bachy Joint Venture (DSBJV) will start by removing a 5m layer of ground from Lower Queen Street. This will lower the ground level sufficiently to allow excavators to start digging under the CPO building from Lower Queen Street.
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A single 25m wide trench will be excavated in Lower Queen Street and two 10m wide trenches under the CPO (the two future CRL platforms will be located on the far sides of the station).
DBSJV is also completing the weight transfer of the 106-year-old Category 1-listed heritage building onto a series of underpinning frames, which will protect it from damage while CRL infrastructure is built underneath.
CRL tunnel box construction is expected to start at this location at the end of this year, once the trench excavation reaches the required 14m depth, and be finished in mid-2019. After this time, the trench will be backfilled, Lower Queen Street reinstated and the CPO rebuilt with basement and ground floor levels.
City Rail Link Limited’s Chief Executive Officer, Sean Sweeney, says: “The start of trench excavation on Lower Queen Street marks a significant point in the construction process. It takes us a step closer to building the CRL rail tunnels at Britomart Station and connecting them with the tunnels being built within the Commercial Bay development.”
CRL is the largest infrastructure project ever to be undertaken in New Zealand. The 3.45km double-track underground rail line will run from Britomart Station, through Auckland’s CBD via new stations at Albert Street and Karangahape Road and connect with the existing Western Line at a redeveloped Mt Eden Station.
Jointly funded by the Government and Auckland Council, the CRL is on track to be completed in 2024.