Officials said the main benefits of the project were turning Britomart from a dead end station to a through station, provide three more stations in the heart of the city (at Albert St, Karangahape Rd and Mt Eden) and enable a much higher frequency across the rail network.
Chief executive Stephen Town said the Government was committed to the link, but there was a small rub around the issue of timing when it comes to funding its share.
The council, he said, did not have bankable funding agreement with the Government at this point, but there would be no adverse impact on the budget in the first three years of the 10-year budget.
"Our prudent advice to you is we are in pretty safe territory," he said.
Mr Town said work was ready to go in 2016 on 'enabling works' as part of the redevelopment of the Downtown Shopping Centre.