Main work on the $2.5 billion City Rail Link is due to start in May next year, beginning with a new entrance for commuters at the rear of the Britomart train station.
The largest rail project in New Zealand, eclipsing the $1.4 billion Waterview motorway connection, has been on the planning and political books since 2009.
Mayor Len Brown picked up the former Auckland Regional Council project as his number-one priority for the new Super City, although the Government is dragging its feet and will not start funding its $1 billion share of the cost until 2020.
Senior council staff have told the Herald that main works on "cut and cover" tunnels from Britomart through the redevelopment of the Downtown Shopping Centre and up Albert St to Wyndham St are programmed to begin next May.