Mr Crosby said council ownership of Turret Rd and 15th Ave would allow more control of when the two roads would be widened. Capital works projects on council-owned roads were funded 50/50 by the council and the agency.
The last published cost estimate for the Turret Rd end of the Hairini Link project was $53 million, although Mr Crosby did not place much reliance on this 2009 ballpark figure.
He stressed the council and the agency were discussing concepts. Options included the agency taking over Route K and its debt in exchange for the council taking over Turret Rd and 15th Ave.
The first thing the council was looking to achieve was for the agency to take over the full maintenance of Route K. Other options included a deferred programme for the agency to take it over and a partial repayment over a number of years. "It is early days yet."
Mr Crosby said the underpass was a key project and there was a strong commitment to remedy the pinch point at Turret Rd. Construction of the $58 million underpass funnelling Welcome Bay traffic directly into the Hairini causeway was due to start in 2014-15.
Welcome Bay councillor Bill Grainger opposed Turret Rd and 15th Ave going back to the council because of the commitment by the Government to do the project - even if it meant the Turret Rd end would not happen until the 2020s. "I don't want to see it as part of a trade-off."
He said the pressure would come on almost immediately for the council to widen Turret Rd and 15th Ave once the underpass opened. In the long term, a deal could go against the council.
Cr Grainger said the council had put its head in a noose by building Route K and now it was trying to get out of it. If the council took over the two roads, he could not see it being able to afford the widening for a long time.
"That is why I want to put pressure back on the Government to honour the promise it made."