A large slip on Ngaio Gorge Road in Wellington is expected to keep the busy route closed for much of the week.

The crumbling of yet another Wellington hillside over the weekend is expected to cause a headache for commuters heading into the city from Khandallah and Ngaio.

The slip that came down across the Ngaio Gorge Rd in the small hours of Saturday morning had become "massively bigger" by Sunday, Wellington City Council spokesman Richard MacLean said.

KEVIN STENT Abseilors and engineers are assessing the scene of the slip.

Looks a whole lot worse this morning... pic.twitter.com/e5EYuxyYVT — Simon Coggins (@simoncoggins) July 29, 2017

About 50 truckloads of rocks and rubble had come down onto the road, which MacLean said would not be likely to reopen until later in the week.

Engineers were at the scene on Sunday and abseilers were at the top of the slip to see if anything more was likely to fall.

KEVIN STENT Engineers are assessing the slip to work out if more rubble could collapse.

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"Pretty much a large section of this bluff has come down overnight, it's not a good situation," MacLean said.

Plans to bring in a 20-tonne digger to "climb up the rubble and try and remove the unstable material on the slip-face," on Sunday were later scrapped.

KEVIN STENT/STUFF The road is expected to stay closed until later this week.

Instead, "sophisticated monitoring machines" would be left on the slip overnight to see if it was still moving.

The rubble blocking the road would not be cleared until the debris that looked like it could come down had been cleared away.

MacLean said motorists could use other roads like the Ngauranga Gorge, Onslow Rd, and Churchill Drive via Wadestown.

KEVIN STENT/STUFF Ngaio Gorge road in Wellington is completely blocked off after a slip that began early on Saturday morning became much worse on Saturday night.

The Old Porirua Rd had been closed due to congestion and safety problems, but would stay open to residents.

Pedestrians could still use the Trelissick Park track to get past the landslide.

There would be no buses between Kaiwharawhara Rd and Khandallah Village, Metlink's website said. Anyone hoping to bus into town could catch a bus on Hutt Rd, or at Khandallah Village.

A slip below St Gerard's monastery on Mt Victoria had come down earlier in the week, MacLean said. The council had closed a pathway leading from the monastery down to Oriental Bay as a precaution, but the building was not in any danger.

Two houses that were evacuated late last week after the land slid away beneath them remained empty over the weekend.

A house in Evans Bay remained in a precarious position after the land beneath it fell away on Friday, and homeowners would have to get engineers in to assess the area, and make a call as to whether the house was safe or not, MacLean said.

The damage done by a slip that saw a home evacuated on Devon St in Aro Valley on Thursday night included broken sewer mains.

"There's going to have to be some repairs done, I can't imagine they'll be going in over the next few days."

Earlier on Sunday, another slip was causing traffic headaches for commuters taking State Highway 2 between Wairarapa and Wellington.

The slip was blocking the southbound lane of the Rimutaka Hill Rd, as well as part of the northbound lanes.

Police saidlarge rocks and dirt had come down, and cars were swerving to avoid it, risking driving into oncoming traffic.

The New Zealand Transport Agency said the slip had been cleared.