The major slip near Kaikoura that has blocked State Highway 1 and the Christchurch to Picton railway line will not reopen until Thursday at the earliest.
The closure is delaying trucks trying to deliver supplies to Canterbury.
Up to 20,000 cubic metres of earth and rocks fell onto the road at Peketa, about 15km from the town, on Friday evening.
Canterbury regional civil defence controller Jon Mitchell says the landslide is affecting the supply of goods to Christchurch and is just one more thing for staff managing the aftermath of the earthquake to cope with.
Mr Mitchell says the slip effectively means there's now an emergency over three quarters of the Canterbury region.
Freight company TNL runs about 60 trucks between Cook Strait and Christchurch on a weekday, and says the number of trucks on the road have risen sharply since the earthquake.
Weekend supervisor Amad Prasad says drivers who've reached their legal limit of hours worked are having to be rescued from delayed trucks.
The TranzCoastal passenger train service has been suspended. KiwiRail says a bus replacement cannot be provided, as the alternative route for coaches would almost double the journey time and miss out most stops along the route.
A detour is available for cars on Route 70, the inland Kaikoura route, which the Transport Agency says will add about 90 minutes to driving times.
Heavy vehicles must use State Highway 63 (Wairau Valley) and State Highway 7 (Lewis Pass), which will add an extra two-and-a-half hours to the journey.
Trucks are able to carry away only six-cubic-metres in each load and it will be Thursday at the earliest before the road is re-opened.
The Transport Agency's North Canterbury area manager, Barry Stratton, says the site will need continued monitoring and more work to make it stable.
He says he's anticipating the issue will last for some time.
Mr Stratton says the fallen material is very dry, and should be wet if rain caused the slip.
Supplies run short in Kaikoura
The Kaikoura Business Association says some supermarket supplies are dwindling and are in danger of running out as efforts continue to clear the landslip.
The business association's chair and local motelier, Stephan Rattray, says the town is at near capacity because of people seeking respite from Christchurch.
He says businesses need the road open.
Mr Rattray says even bottled water disappeared off the shelves in two days late last week and Kaikoura is unable to get supplies from the North Island, so the Christchurch link is vital.
A KiwiRail spokesperson, Ruth Larsen, says it doesn't send freight directly to Kaikoura by rail, normally using trucks from Blenheim.
She says because trucks are taking priority freight to Christchurch that's likely to be affecting supplying towns such as Kaikoura.