The journey from Christchurch to Picton is expected to take an hour more than usual this week

NZTA is warning motorists to factor delays up to an hour when travelling the 335-kilometre route while road works take place.

Areas in Kaikoura and Marlborough will have delays, as rock scaling and a line relay is completed across State Highway 1.

Journey manager Tresca Forrester says the work is done before Easter - and avoids any of the summer months.

She says they have a short window between October and March to complete any work - with rock scaling done at the end of this month to prepare the highways before winter.