A 2.6 kilometre link between Lyttelton and the Summit Road will take over two years to complete.

Work should begin later this year on the Evans Pass section of Sumner Road, at a cost of up to $60 million.

The Christchurch City Council will foot one-fifth of the bill, and the NTZA will make up the rest.

Council Facilities and Infrastructure director David Adamson says the work is essential.

"I think the whole of the South Island should be reasonably happy because it adds a level of resilience to the roading network."