Auckland Transport expects to start digging up one of the central city's main streets next year to build the City Rail Link.
The downtown rail tunnel's final hurdle fell yesterday when the Environment Court dismissed the last appeal against it.
Early works for the $2.5 billion train route are expected to start in November.
Auckland Transport said work on the tunnel along Albert Street would start next May.
Chief executive David Warburton told Morning Report tens to hundreds of millions of dollars have been spent buying property for the project.
The 3.6 km underground railway line will run from Britomart, through the CBD, to Mount Eden Station.
Six appeals were lodged in relation to the land designation.
Five were settled, and the sixth was dismissed by the court yesterday.
Auckland Transport said it was a big step forward for the project, which was first suggested almost 100 years ago.