From Picton to Waipara, about 24km of new chip sealing is planned over several different sites for this summer.
Contractors will also be installing a network of new safety and speed restriction signs along the route, with initial work already under way.
NZTA is also planning on widening the road at several critical points to help ensure that the larger number of cars and trucks using the alternate route can travel safely in both
directions.
"Additional slow vehicle bays are also planned to help faster moving traffic pass safely while slow vehicles pull over, and more safe rest areas for truck drivers are being made available all along the route.
"We're working closely with freight operators and councils to determine the best locations for these additional truck pull-over spots."
Some delays were inevitable while work was carried out, but contractors would do everything possible to minimise disruptions and provide as much notice as possible.
- Greymouth Star