A look inside the Manawatū Gorge, which closed after slips fell in April 2017.

The Manawatū Gorge was once the main link between Hawke's Bay and Manawatū, but now it is littered with rocks across both lanes. Reporter Miri Schroeter and visual journalist Grant Matthew got an exclusive view of the Manawatū Gorge with the NZ Transport Agency.

The rumble of vehicles weaving around the hillside has been replaced with an eerie quiet, save for the sound of birds, perhaps intent on reclaiming the highway as their own.

It is clear nobody else wants it.

1 of 5 GRANT MATTHEW/STUFF NZ Transport Agency regional transport system manager Ross I'Anson stands at one of the latest large slips on the closed highway. 2 of 5 GRANT MATTHEW/STUFF Tyre marks show where vandals accessed the road after it had been closed off to public use. 3 of 5 GRANT MATTHEW/STUFF NZ Transport Agency regional transport system manager Ross I'Anson unlocks one of the many gates preventing the public from using the Manawatū Gorge. 4 of 5 GRANT MATTHEW/STUFF An arial view of one of the largest slips on State Highway 3 through the Manawatū Gorge. 5 of 5 GRANT MATTHEW/STUFF Rocks and slips cover the closed Manawatū Gorge road.

Gravel has broken free from netting. Rocks the size of car tyres sit on the road like paper weights, stubborn reminders that the Manawatū Gorge is not safe for motorists.

Skid marks and trash betray the activities of those who would disregard the warning signs.

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GRANT MATTHEW/STUFF Aerial view of one of the new larger slips on the highway.

The gorge route was closed on April 24 after several slips blocked the road. Initially, work was under way to clear the slips but more loose material threatened the safety of workers, so the maligned section of State Highway 3 was closed indefinitely in July.

Since then, more rocks have come crumbling down and slips cover the stretch of road.

NZ Transport Agency regional transport system manager Ross I'Anson​ said small rocks often crumbled on to the road when it was still open but they were swiftly crushed to dust by cars.

GRANT MATTHEW/STUFF Rocks and slips litter the Manawatū Gorge road, which was deemed too unsafe for public use.

Now gravel reaches over the median strip and nets and metal barriers have been ripped apart.

Towards the Ashhurst end of the gorge, at Kerry's Wall, the road is buried under a tower of rocks, so access further into the gorge is impossible. A bridge was also taken out by loose material.

The eastern side of Kerry's Wall started peeling off, I'Anson said.

GRANT MATTHEW/STUFF Rocks the size of tyres block State Highway 3 through the Manawatū Gorge.

"As the hillside's moving it's been pushing the face of the wall off. We are getting more material down all the time. It's only small amounts at the moment but it has added up to quite a bit of material on the road."

The agency expects up to 630,000 cubic metres of material could drop near Kerry's Wall, which would be 170 times larger than both slips in April.

But it was hoped to come down in four stages, which would lessen the risk of blocking the Manawatū River, I'Anson said.

On the Woodville end, the gorge is blocked off by road cones, followed by a thick metal barrier and a barbed wire fence.

Security was beefed up after people broke through a barrier to use the road as a drag-racing strip, leaving behind a spaghetti sprawl of tyre marks.

Now, the road is only used by the transport agency and contractors every one-to-two weeks to clear the gutters when they become blocked by rock fall.

While plans are under way to find a location for a new highway, there are no plans for the "high-risk" gorge.

I'Anson said the transport agency needed to discuss a long-term solution with partners such as councils and the Department of Conservation.

"The public may think it's a great thing to have open but then they've got to rely on someone to maintain it. Someone to keep them safe.

"There would have to be a decision made between that group to determine what's going to happen."

A decision on an alternative route to the Manawatū Gorge is expected by mid-December.

There are four options being considered: An upgrade to the Saddle Rd, a new road north of the road; a new road south of it; and a new road south of the gorge towards the Pahiatua Track.