Central NZ weather and traffic problems make for travel bedlam

It was a mangled mess blocking a busy highway - a haulage truck smashed into Marlborough's Wye Bridge, the impact sending its engine over the edge and into the river below.

The driver was left trapped inside the squashed cab. Somehow he escaped with just moderate injuries.

But the crash on the one-way bridge south of Blenheim caused major disruption for travellers, closing State Highway 63, which has been the main access route between Picton and Christchurch since the Kaikoura earthquake.

Eventually, officials were able to open a ford beside the bridge for motorists to get through.

The truck has been removed but the New Zealand Transport Agency says the bridge has suffered "significant" damage and could be closed for some time.

Making problems worse was that the crash cut a main fibre-optic cable, which knocked out internet to thousands of homes and leaving many businesses at the top of the South Island without EFTPOS.

Further north in Wellington, Interisland ferries sat idle at the terminal with all services cancelled.

They're due to resume later on Sunday, after monster waves in the Cook Strait.

"We've seen six-metre waves down on the wave-rider down on the South Coast, and occasionally getting up to nine to 11 metres," resident William Nepe says.

To put that in perspective, the average single-storey house is only four-and-a-half metres high.

"This is not something you see day to day. This is quite a significant southerly event," he says.

Although not everyone was keen to stay on shore, with a number of surfers braving the weather.

There was some relief for travellers in the central North Island, with the Desert Road reopened on Sunday afternoon after being blocked by snow.

Motorists are being warned to check the latest conditions before driving.

Newshub.