NZTA says the damage at Waioweka Gorge on State Highway 2 - from the weekend's flooding, is extensive

More than 40 people had to be flown to safety on Saturday - after being cut off in their cars.

Crews are working from both ends of the route, with no safe way through the central section.

NZTA Controller Rob Service says with more bad weather expected tomorrow - crews may need to be withdrawn.

He says motorists should delay travel where possible - or allow significant extra time to use detours on State Highways 35 and five.