The 2,200-t TBM, named Alice and launched at the end of November 2013, will build twin 2.4 km-long tunnels, both 13.1m-diameter, to connect Auckland’s Southwestern (SH20) and Northwestern (SH16) motorways as part of the city’s Western Ring Route. Each tunnel will carry three lanes of motorway traffic. Alice is driving 25-40 m below the surface. The TBM is due to complete construction at the end of 2015 and the tunnels open to traffic in early 2017.

The TBM stops boring every 2 m to construct the concrete tunnel lining. Each completed ring is grouted into place. Alice then continues her tunnelling, using the newly positioned ring from which to push off.

At 04.03.2014 the TBM advance was 432 m with 210 rings installed. When the TBM reaches the 500m, it will take a break of approximately three weeks, so that a special gantry can be assembled inside the completed section of tunnel. A white 95 m-long, 400 t gantry, as big as Alice, will soon head underground to place the services culvert that will run under the motorway through the Waterview tunnels and carry the mechanical and electrical services needed to operate the tunnel. It’s the first time in TBM history that tunnelling and culvert placement have been separated. Click here for a video and nz/16 for tunnelbuilder archive. Visit http://www.nzta.govt.nz. 11/14.