THE TUNNELS The 3.45km twin-tunnel underground rail link includes tunnels up to 32 metres below city centre streets.
Cut and Cover Tunnel Driven Tunnel Existing Western Line
SKY TOWER
Karangahape Road Vincent Street Mayoral Drive
Connection with Western Line
Symonds Street
Central Motorway Junction
Pitt Street
70m
AOTEA CENTRE
BRITOMART STATION
Albert Street
3600m 0m
1000m
Re-developed
Britomart Station CONNECTS TO EXISTING RAIL NETWORK
Becomes a through station, enabling more trains to run more often.
Platform 11m below ground
3
MINUTES
2000m
New
Aotea Station
Expected to be New Zealand’s busiest train station, with entrances on Wellesley and Victoria Streets.
Platform 15m below ground
The twin-tunnel underground rail link will unlock our public transport network and transform the way we travel around the city. The alignment of the underground tunnels generally follows the road network to minimise the amount of private property affected by the project. Due to the gradient of the landscape between Britomart and the western line at Mt Eden and the limited climbing capacity of the electric trains, the twin tunnels will vary in depth. At each end of the tunnels (Albert Street and Mt Eden) it will be shallow enough to construct the tunnels using the ‘cut and cover’ method. Cut and cover tunnels are built by excavating from the surface and installing retaining walls to retain the soil and stop water from entering the site. Tunnels are then constructed inside the trench and the completed structures backfilled. The CRL tunnels at the northern end of Albert Street (between Customs and Wyndham Street) have been constructed by Connectus (a McConnell Dowell – Downer joint venture) using this cut and cover method. Connectus will finish back-filling the trench in 2019 and reinstating this section of Albert Street in 2020, delivering an enhanced
3
MINUTES
New
Karangahape Station Entrances on Mercury Lane and Beresford Square
Platform up to 32m below ground
Digging under the central city has provided an opportunity for City Rail Link to contribute to cultural sustainability by conserving the built heritage of the historic Chief Post Office building and literally digging into the area’s colonial past. During the reclamation of Auckland’s waterfront in the mid-1800s, household rubbish and building debris were thrown in to the fill. When CRL started excavating around and under the Chief Post Office, many historical artefacts were recovered, from torpedo-shaped glass bottles and earthenware pots to iron
implements and shoes. Some of the items are considered rare finds in New Zealand. The heritage items have been documented by the project’s archaeologist and CRL will be looking at ways to display some of them in the new stations. The CRL project has also dug up some original Auckland infrastructure, including wooden Queen Street wharf piles from the 1850s, brick stormwater pipes from the 1860s, tram tracks from 1902 and wooden building foundations from 1909.
3200m
3
MINUTES
Re-developed
Mt Eden Station
New station building and platforms catering for the existing Western line and the new CRL line.
Platform in an open trench
streetscape with wider footpaths, new street furniture and trees and new stormwater infrastructure. The Link Alliance will employ the same cut and cover method as it undertakes its Aotea Station and tunnel works further up Albert Street between Wyndham Street and the lower end of Mayoral Drive. However, from Mayoral Drive to Mt Eden, the CRL twin tunnels will be constructed using a seven-metrediameter tunnel boring machine (TBM), about half the size of the TBM used to create Auckland’s Waterview Tunnel. When the CRL tunnels reach Mt Eden, they will appear at the surface as ‘dive’ structures, similar to the rail trench at New Lynn Station. The tunnel portal will be located just south of the Flower/Nikau Street intersection. Set-up and operation of a TBM requires a large worksite, both to house the pre-cast sections that line the tunnel and to retrieve the excavated material as the TBM travels forward. As there are limited spaces in the city centre to establish such a large work site, the Link Alliance’s TBM operation will be at the Mt Eden Station worksite.
Digging up Auckland’s past At Mt Eden, Jeffie, the mini tunnelboring machine encountered remnants of what is thought to be a 30,000-40,000-year-old whau tree – a light-weight wood used by Māori to create floats on nets. It was found 15 metres underground, under a layer of basalt rock, indicating that it had been knocked over at the edge of a basalt flow and smothered by the lava rather than catching on fire. If you’re interested to see and learn more about the artefacts we’ve found, be sure to visit the Archaeology section of CRL’s website.
*Scale is accentuated
CONNECTS TO EXISTING RAIL NETWORK