Commuters down Christchurch's Halswell Road are in for the long hall when it comes to road works

Sixty-million dollars worth of construction on State Highway 75 between Dunbars and Curletts Road is due to start tomorrow , and is expected to take two-and-a-half years.

NZTA's South Island Regional Manager System Design Richard Osborne says they're aware it's a significant amount of time.

He says they'll be doing their best to minimise the impact, by keeping traffic going in both lanes, for most of the time.

The upgrades aim to improve bus reliability, and includes shared pedestrian and cycle ways.