Wellington Scoop

Ngaio Gorge Road reopens after another slip closes it for six hours

The Ngaio Gorge Road is to reopen for traffic and pedestrians at 4pm, after being closed since mid-morning by a small slip. Here’s how today’s news developed.

News from NZ Police at 10.40am
There is a new slip on Ngaio Gorge Road, near the location of the recent major slip. The road is closed in both directions until further notice.

News from MetLink at 10.30am
The Ngaio Gorge Road is closed again due to another slip. Buses 43, 44, 45 and 746 are back on diversion routes.

News from Justin Lester at 12.30
The new slip on Ngaio Gorge is small, but rocks are falling so we have abseilers investigating closer.

News from WCC at 1.50
It was a small slip but rocks are still coming down. Abseilers are checking slope/removing loose material.

News from WCC at 2.30
We hope to get the road open later this afternoon but no guarantees at this stage.

Photo: WCC

News from WCC – August 15
Two lanes are now open on the Ngaio Gorge Road during peak hours, with speed restrictions in place. Any further work required will be carried out under Stop / Go and or using temporary traffic lights.

All restrictions on the Old Porirua Road have been lifted.

News from WCC – August 14
One lane of the Ngaio Gorge road was reopened from late this afternoon. There is a stop-go system operating to allow access from both directions, and speed restrictions are in place.

The section of road restricted to 30kph is wide enough for cyclists and vehicles but needs to be treated as a shared zone as there is no dedicated cycle way. There is a dedicated footpath for pedestrians along the re-alignment section separated with delineators.

There is still a lot of work to be done on the area, so please be patient in the meantime.

MetLink advises that bus routes 43,44 & 45 are now back to their normal route.

Earlier News from WCC
Wellington’s Ngaio Gorge Road will, all going well, be reopened to traffic in time for this afternoon’s evening rush hour.

Photo: WCC

Work continued this weekend to complete a temporary realignment of the uphill lane and also to secure a line of shipping containers to protect the roadway from any further rockfalls.

The gorge, an important link between Wellington’s CBD and the western suburbs, has been closed to traffic since a large landslide blocked the road on the weekend of 29-30 July.

The site will have a restricted speed limit of 30kmh in both directions. During off-peak periods the road just above the slip site will continue to be one-way only (controlled by temporary traffic lights) while work continues on the construction of a retaining wall (this work is not related to the landslide).

Earlier News from WCC
The Ngaio Gorge landslide has now been cleared and we are aiming to reopen the road on Monday afternoon, after installing the container wall. We are aiming to have at least a temporary one way system in place with a restricted speed limit of 30kph in both directions.

The cordon at the bottom of the work area has been moved up the road, restoring unimpeded access to all the businesses in the lower part of the area

Photo: WCC

Four shipping containers were delivered to the site yesterday, and these will be filled with concrete blocks and placed as a rockfall protection barrier as work continues.

Most of the preparation works for a temporary road adjacent to Trelissick Park is also complete with some minor cleaning and paving works planned over the weekend.

Photo: WCC

News from WCC – August 9
As of this afternoon, 98 per cent of the Ngaio Gorge slip material has been removed, with a few truck loads being stockpiled on site to use on various areas of forward work.

Anchor drilling will start tomorrow morning, with containers and ballast blocks delivered from tomorrow afternoon.

As part of the road realignment, a vegetation crew will start clearing the garden area and overhanging trees, and any leveling required will also take place.

The road closure on the lower end of the hill will be moved closer to the site from 6am tomorrow, allowing the businesses in the area to have unobstructed access. The bottom of Old Porirua Road will still be manned to prevent uphill traffic.

Earlier News from WCC
Another 1100 odd cubic meters of material was carted away from the Ngaio Gorge slip yesterday, with the remainder on its way today, so lunch time should see the end of the stream of heavy trucks and hopefully the reopening of the section of Ngaio Gorge Road between Old Porirua Rd and the last business.

It might be a bit tight turning around at the end so please take your time and be patient.

The next stage involves drilling some holes into the base of the slip to anchor the planned container wall. This work might take a couple of days depending on how hard the rock is. We will then install a pile of shipping containers to protect the public from further rubble that may come off the tip face.

While all that’s going on, we will also begin preparing a temporary road through the lay-by near Trelissick Park to allow space for us to place the container wall in the downhill lane, and leave room for traffic to flow in both directions during peak hours.

Work also continues on the removal of some loose rock from the face of the bank on the next bend down from the main slip, which should be completed in the next few days.

Following that we will remove a couple of smaller slips from further up the road to ensure things are as safe as possible when we finally get the road open to all traffic.

The work on the retaining wall that was happening before the slip is likely to continue into November, and there will be traffic signals in place to guide you around that site during off-peak hours.

News from WCC – August 8
We have removed somewhere in the order of 4500 cubic metres of material from the Ngaio Gorge slip so far, with an estimated 1200 to go. There is a possibility that the road might be reopened early next week.

We have started to bring some concrete blocks to the site to use as a safety barrier while the lower slip area is being cleared by the abseilers. These are expected to be used for the temporary works around the main slip when scaling of the lower area is complete.

Another day and a half and we can start some remedial works which will at this stage include a bit of road realignment and building a container wall.

We are also removing a small amount of debris from the hillside about 30m down the hill so we don’t need to go back again. This will be done by abseilers at the same time as the current work is completed and is unlikely to cause any additional delay.

Photo WCC

News from WCC – August 7
Carting of material from the Ngaio Gorge slip continued over the weekend with 3500 cubic meters taken away over the couple of days.

We are about a third of the way through the pile at the moment and this phase of the operation will continue to mid–late this week, with some safety related works to follow including realignment of the road away from the slip and installation of a barrier system to catch any further rocks or material that may be dislodged by the forces of nature.

As our primary responsibility is safety, we have installed some monitoring points in and around the slip face so we have some idea of what is happening in the vicinity. We will be monitoring these on a daily basis and implementing any needed solutions if things change.

Old Porirua Road remains one way down for safety reasons. Residents, pedestrians and cyclists continue to have access with general traffic still excluded for now. We appreciate that it can be a bit of a trip around for residents but believe that the measures in place should ensure that there are no serious incidents on this narrow windy road in the short term.

News from WCC – August 4
We started carting material out of the Ngaio Gorge early this afternoon with the operation going full blast into next week. From tomorrow morning we expect to have 10–12 truck and trailer units operating from dawn to dusk with a similar number of 10 yard trucks.

Material will be carted to various sites around the region and all going well we are expecting that part of the operation to be completed towards the middle part of next week.

Work will then commence on a temporary re-alignment of the road and installation of appropriate safety measures to minimise the risk of falling debris to passing traffic when the road is finally reopened.

Earlier News from WCC
There was a significant slip (rough estimate of 100 tonnes) in the Ngaio Gorge yesterday afternoon, but the safety plans worked as expected, and there was no risk involved. The digger that was working in the area had forewarning from the monitors in place, and was out of range 12 minutes before any materials fell.

We’re working closely with the Geotech crew, monitoring systems are in place, and we are now reassessing the plan so we can move material from a new angle.

The landslide removal is progressing as planned today, with removal of material likely to start this afternoon.

Old Porirua Road is open from the downhill route to residents in cars, cyclists. Pedestrians are permitted to walk either way, but to do so with caution..

News from WCC – August 3
Good progress on clearing the Ngaio Gorge landslide is being made with the long reach excavator and depending on progress between now and the end of the day we may be able to start carting material out by mid-morning Friday.

At this stage we are planning to cart all weekend and hope to have that part of the operation completed sometime on Wednesday. There will be a need to install some protection for traffic which should be installed over the following couple of days after spoil removal.

Trelissick Park is open to the public for awalkway thoroughfare from upper Ngaio Gorge Road to Kaiwharawhara Road.

Photo: Justin Lester

News from WCC – August 2
A lot of material was removed from the top right side of the Ngaio Gorge slip overnight. This work was carried out while sluicing took place, as separation of the work site was deemed safe. An access ramp to a large work platform from the uphill-left side of the slip is in action with some very solid bedrock uncovered.

All going well, it is possible that material can be removed starting Friday.

Please note: Old Porirua Road is accessible from the downhill route to residents (checking in with Traffic Management Team) and cyclists only. Businesses are open as usual within the cordon.

News from WCC – August 1
Work continued today to clear the slip in Ngaio Gorge Rd with sluicing of loose material from the upper parts of the slip zone. A helicopter was utilised to drop water on to the slip.

A large excavator was used to put in a track from where further areas of unstable mainly rocky material was being dislodged and this work will continue tomorrow.

This afternoon the geotechnical experts and abseil specialists were checking the area above the slip to determine if further work will be necessary in this area. Monitoring of the slope using special survey equipment was also implemented.

The experts will convene tomorrow morning and if it is deemed safe the excavator will continue to bring down the unstable slip face. When this work is completed the contractor will commence removal of the slip debris, which we think will be later in the week.

As a result of Ngaio Gorge Rd being completely closed to traffic, increased traffic volumes are most noticeable at the Onslow Road/Hutt Road and Tinakori Road/Park Street traffic signals as these are the main alternative routes from Khandallah to the city.

News from MetLink
Due to the slip on Ngaio Gorge Road, all buses to and from Khandallah Village are affected until further notice. Diversions are in place. We are now anticipating these diversions being in place into next week. Please note that bus arrival predictions for these changes will not be reflected in Real Time Information (RTI). Unfortunately our Metlink contact centre staff will also not have that information available to them – we ask for your patience as the buses will also most likely be running late because of the extra traffic congestion. You can however check RTI to see if your usual bus stop is open or closed. You may also wish to catch a train – but please note that buses are replacing trains due to scheduled maintenance after the morning peak.

GeoNet: 1300 cubic meters of rock and debris

News from WCC – July 31
Ngaio Gorge is expected to be closed until at least the end of the week because of the weekend landslides. No more debris came down overnight, and preparation has started for slope stability and material removal works.

A helicopter was expected to arrive in the gorge to begin sluicing at the landslide site about 4.30pm today. The sluicing aims to bring down loose rock so a 20-tonne excavator can operate safely on the site. The stability of the landslide will be reassessed tomorrow morning.

Old Porirua Road, above the slip, is now closed to all through traffic. Residents along the road are still allowed access (downhill only) as are cyclists.

· Motorists are asked to take care and keep speeds down on alternative routes that have become busy due to the closure of Ngaio Gorge Road. This includes Onslow Road and Wadestown Road – where there have been complaints that vehicles are travelling too fast through the shopping area.

Photo: WCC

News from WCC – July 30
The Ngaio Gorge Road, one of the main routes between central Wellington and the western suburbs, will be closed for several days while workers attempt to stabilise and clear a large landslip.

The landslide has grown significantly overnight since the first material came down off a steep bluff and closed the road early on Saturday morning. The road is now completely covered by large boulders and rubble.

Motorists are urged to use other routes like the Ngauranga Gorge, Onslow Road and Churchill Drive via Wadestown.

The nearby very narrow Old Porirua Road has been temporarily closed to through traffic due to congestion and safety problems. It will still be opened to residents.

Geotechnical experts and abseilers have been examining the landslip site this morning – and there were plans to bring a 20-tonne digger onto the site this afternoon. The machine was to be used to bring unstable material off the slip face before work starts to clear the roadway. However these plans have been abandoned after more boulders and rubble fell on to the road at midday.

Engineers and Wellington City Council staff agree the situation today is too dangerous. They will monitor the slip today and reconvene tomorrow morning to consider their options in terms of stabilising the site and clearing the debris.

News from WCC – July 29
The Ngaio Gorge is likely to be closed for several days following a big landslip this morning. The road – one of the main routes between central Wellington and the western suburbs – will be closed for at least the rest of the weekend and possibly early next week following the large landslip.

Two very closely adjoining landslips have sent large boulders onto the road from a bluff above. Contractors started removing the rubble this morning but were pulled back because a lot of rock still coming down this afternoon.

Consultant engineers, the Wellington City Council and the Police are not prepared to open the road again until it’s safe. At the moment the engineers are trying to figure out how they’ll remove the large amount of material that’s still above the road – it might involve a helicopter and monsoon bucket but that decision has yet to be made.

Probably about five or six truckloads of material has come down – mainly big boulders.

The nearby very narrow Old Porirua Road has been temporarily turned one-way (downhill) following aggro between motorists this morning who’ve been trying to use it as an alternative route. Motorists are urged to use other routes like the Ngauranga Gorge, Onslow Road and Churchill Drive via Wadestown.

Earlier news from WCC
The Ngaio Gorge in Wellington – linking the central city with the Ngaio and Khandallah area – was closed to through traffic this morning by a large slip.

The road was likely to be closed until at least mid-morning while engineers and contractors examine the landslide.

News from WCC – July 28
There’ve been delays for citybound traffic on Evans Bay Parade this morning while a sizeable slip was cleared from the roadway near Point Jerningham.

There’s also a large slip on the corner of Branscombe Rd and Ironside Rd in Johnsonville. Expect delays in the area.

And at 7am Ngaio Gorge was down to one lane with a large slip blocking the citybound lane.

Devon Street in the Aro Valley remains closed to through traffic following a large slip overnight.

RNZ: Slips cause evacuation of two houses

News from NZ Police – July 27
A section of Devon Street in Aro Valley, Wellington, has been cordoned off this evening after a slip has come down. One house has been evacuated as a precaution.

The road will be closed overnight between the Devon St/Essex St intersection, and the intersection of Landcross St and Fairlie Terrace.

This also includes pedestrian access to Victoria University via a walkway which runs off Devon Street.

Contractors are attending this evening and will further assess the site tomorrow.

People are asked to avoid the area if possible.

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  1. Ken W, 10. August 2017, 8:26

    Using the alternate temporary road through the park should have been done from day one at the Ngaio slip. Most of the 100 tonnes of the material visible in the photo was ‘man made’ as contractors loosened the clay following the small slip, thus creating a landslide. Then they put it on to the road and took photos while preparing to put needed anchors into the hill.

  2. Diane Calvert, 11. August 2017, 10:39

    It will take 6-8 months to get the Ngaio Gorge Road fully operational [via twitter]

  3. Cr Calvi-Freeman, 13. August 2017, 12:22

    Thanks to Deven Singh and his team of council engineers, and thanks also to all the contractors involved including geotech engineers, helicopter pilots and traffic control operatives etc. Also to the WCC communications team for such great updates on line.

    The gorge reopening will take place as quickly as possible consistent with public safety. Reopening earlier via the alternative alignment (as suggested by Ken W) would have placed road users in danger of massive falling rocks. Having been to the site I can attest to the fact that single greywacke boulders the size of refrigerators and weighing several tonnes came down without warning. The right shaped boulders can roll considerable distances and could easily take a car off the road.

  4. Ken W, 13. August 2017, 14:26

    As the majority of the slip was “man made” and the alternative road could have been used by lining it with containers and was not, well ….a job well done all the WCC spinners and hangers-on.