Britomart developer Cooper and Company wants the works to be carried out during Auckland Transport's extensive City Rail Link reinforcing works under the CPO, due to start soon.
Chris Darby, Auckland Development Committee deputy chairman, backed the strengthening scheme and praised Cooper and Company's work at Britomart.
"It does make some sense that the council should at least look at doing the strengthening works which could be very affordable against the cost of ignoring that in the works we're doing in the enabling stage of the CRL," he said.
"The public stake is the most important thing before the commercial stake," he said, adding that early estimates for the work were closer to $7 million.
"If you don't do it now, it would be a phenomenal cost to go back there. It would be silly of us to ignore the opportunity of doing it now," Mr Darby said.
Cooper and Company said a new Transport Centre concourse hall could then be built, possibly linked to the ex-Central Post Office which now houses the train station hub. This would create more public space and increase Britomart's capacity and operating efficiency.
Transport blogger Patrick Reynolds said: "Looks pretty exciting to me - intensive development on top of a rapid transit station is very good for the city, and that elevated form over a high light-filled atrium looks good. Would want to see more design detail but in principle I am supportive."
Deputy Mayor Penny Hulse said it was too early to say if the Cooper plan would proceed but she also praised the company's Britomart, calling it "simply extraordinary".
The investment and development business, owned by Peter Cooper and run by Matthew Cockram, has its eye on the land between the CPO and Takutai Square, an undeveloped slice behind Britomart's glass box to the east.
Mr Cockram said it was time to rethink use of the council-owned land between Commerce, Galway and Tyler streets.
"It's a bit shabby, the way it presents, the way that site interacts with the railway station and carparking. It's unsafe. It's got beyond its useful life. It was fine when it was built 11 or 12 years ago, but there's a lot more people moving around," Mr Cockram said of the use of the approximately 3600sq m block of council-owned land.
Mr Cockram said a 10-level 12,000sq m office block was planned for the site and that block might be worth about $100 million once it was completed. "We have no resolved design or planned start date for the Central Building at this stage."
Chris Meale, City Rail Link project director, said part of the site had already been strengthened when Britomart was built but he could give no price estimate for the strengthening work. Nor had a decision been taken about who would develop the land behind the CPO.
