Since she began her underground travels from Owairaka to Waterview last November, Alice - named after the classic Alice in Wonderland story - had averaged about 4m per day excavating spoil and installing the tunnel's concrete lining.
"At those rates, the machine is well on schedule to complete the first tunnel in late September."
On her arrival at Waterview, Alice will be turned around over the following three months and re-launched on her southbound journey early next year, building the second (northbound) tunnel.
Construction of the two tunnels would be completed at the end of 2015, when they would be fitted out with the services needed to operate them, Mr Mutton said. These included ventilation fans, communication systems and fire protection.
Sixteen cross passages - one every 150m - connecting the twin tunnels would also be built.
The entire project, which included the motorway connections either end of the tunnels, was due to be opened in early 2017.
By the numbers:
-Alice is the world's tenth largest tunnel boring machine.
-She is now 32.5m below the surface.
-600 tunnel lining rings, each weighing 100 tonnes and comprising 10 pre-cast reinforced concrete segments have been installed.
-Alice has removed 197,000cu m of spoil.
-She has consumed $90,000 in power charges and $55,000 for water.
