Most of the preparation works for the City Rail Link (CRL) has been completed and project momentum is shifting to the heavy infrastructure programme. 2021 will see the Dame Whina Cooper TBM’s maiden voyage deep beneath Auckland’s feet and the brand-new underground railway stations materialise.
Mt Eden Station
At the City Rail Link Mt Eden Station construction site the initial 51m of tunnel, from which the Dame Whina Cooper TBM will be launched in April, is making progress. The tunnel has been stabilised for reducing the risk of collapse whilst excavating. A Stabilizing pressure balanced grout mix has been used in the open cracks, joints, fissures or cavities.
The Dame Whina Cooper TBM will start excavating from the Mt Eden tunnel portal in April and it will spend the rest of the year digging the first of two 1.6km rail tunnels. Its route is almost due north from Mt Eden, diving under Spaghetti Junction viaduct then on to Karangahape Station, before arriving at Aotea Station in central Auckland in December.
After completing the first of its two journeys the TBM will be pulled out of the ground at Aotea and relaunched from Mt Eden on its second drive around March 2022. These tunnels will connect up with the cut-and-cover tunnels already created by contracts 1 and 2 under the Chief Post Office Building and up Albert Street.
Contract 1 completion – Britomart
After 5 years in 2021 the technically challenging C1 contract, involving tunnels construction underneath the century-old heritage Chief Post Office (CPO) building, will be completed.
It has been excavated Lower Queen Street, transferred the building's load from its old foundations to temporary underpinning beams, dug beneath the CPO, constructed the new tunnels, and carefully transferred the load back on to the final foundations. The CPO building will resume its role as home to Britomart Station on its reopening in April.
Karangahape Station Mining
Work’s well underway excavating the cavern for the Karangahape Station that will be 32 m deep when finished, the New Zealand’s deepest railway station.
The Link Alliance team - building the station - are using the roadheaders to grind their way through the rock and carve out two platforms. The roadheaders are named after two strong and influential women, New Zealand pioneering aviator Jean Batten and our world champion athlete Dame Valerie Adams.
Karangahape’s platforms are 203 m length, run roughly north-south under the Karangahape Road ridge between Mercury Lane and Beresford Square. The arrival of the TBM is projected to be in September. Thanks to a noise enclosure built over the access shaft in Mercury Lane, the crews can work 24 hours a day. Conditions underground are maintained with fresh air continually pumped into the tunnel.
The TBM will not be involved in mining at the station but will instead use the power of its hydraulic jacks to “push” its way through the pre-dug station before resuming boring to Aotea.
For further information please click here and nz/15 for the tunnelbuilder archive, and also click this link https://www.cityraillink.co.nz/. 06/21.
