Now the heavy lifting begins
You have been down Albert Street in the City Centre recently you might have seen this:

Source: Auckland Council
From Auckland Council:
City Rail Link: It’s almost tunnel time
The top 1.5m of road surface is being removed on the eastern side of the road between Wyndham and Swanson Streets before installing the second half of the temporary steel work required to support the walls of the trench in which the future CRL tunnels will be constructed.
In a few weeks, a temporary deck will be constructed over the top of these steel struts, which will allow working room over the top of the trench for excavators and haulage trucks.
A lane of traffic will be maintained in each direction throughout these works.
On the remainder of Albert Street between Swanson and Customs Street, work continues to tie together and brace the 20m-deep piles installed to support the trench walls.
Excavation has also started on the third part of a traffic deck at the Customs/Albert Street intersection. When the deck is finished, it will form a ‘bridge’ over the entire intersection, letting traffic flow while CRL tunnels are constructed beneath.
……
The City Rail Link is due to be open in 2023.

Source: http://transportblog.co.nz/wp-content/uploads/2017/01/Post-CRL-rail-network-map.jpg