A congested section of highway beside Christchurch Airport will expand to four lanes and feature a distinctive new overbridge.
State Highway 1 between Avonhead Road and Harewood Road, which is currently two lanes, will double in width and include a 2.5 metre wide cycle lane.
A new overbridge will replace the intersection at Russley Road and Memorial Ave and a large piece of curved architecture arcing above it will be constructed to represent the Southern Alps.
Transport Agency southern regional director Jim Harland says the upgrade has become even more important since the February 2011 earthquake.
He says construction should be completed in about four years.