Kia ora and welcome to the Winter 2018 update from the Transmission Gully team.

Great summer season puts motorway construction over halfway mark

Heavy machinery

Heavy machinery taking a break on a section of the alignment near Whitby.

The Transmission Gully motorway project team has made the most of ideal construction conditions over this past summer season to progress the new 27 kilometre motorway. At the end of May, which is when the summer earthworks season officially ended, the project was well over the halfway mark for construction.

Boyd Knights, Construction Project Director says bulk earthworks has progressed well across the entire route over summer, with the weather and commitment of the entire project team playing a big part in this.

“With two years of physical works left to go, we’re in a great position moving into the next phases of works for the new motorway,” says Boyd.

Wellington Gateway Partnership CEO Sergio Mejia is extremely pleased with the progress achieved over the summer season.

“We are on schedule to complete what will be one of New Zealand’s safest, most resilient – not to mention most keenly anticipated motorways, in 2020,” says Sergio.

Key milestones achieved to date include:

Key milestones - May 2018

At its peak this summer the project had a workforce of over 950 people, and since works began on the project, more than four million work-hours have been completed.

Check out the video below showing some of the highlights of construction works happening across the route.

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MPs view project progress

A group of Wellington MPs recently visited the Transmission Gully project to view progress. The site visit, hosted by Wellington Gateway Partnership, was a great opportunity to show the scale of works and the positive impact the new motorway will have on resilience for the Wellington region when completed in 2020.

MPs site visit - May 2018

MPs onsite at the Project’s largest structure – the Cannons Creek bridge. From left, Paul Eagle – MP for Rongotai, Sergio Mejia – Wellington Gateway Partnership CEO, Greg O’Connor – MP for Ōhāriu, Kris Faafoi – MP for Mana and Adrian Rurawhe – MP for Te Tai Hauāuru.

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Construction update

Great progress continues to be made across the project. Over 3.5 million cubic metres of earth has been moved this season, with construction on the new motorway’s major interchanges in full swing. Four of the project’s 27 structures are now complete, and permanent diversion works for the Te Puka and Horokiri streams is progressing well.

Paekākāriki and Mackays Crossing

At the northern end of the project, drainage works for the new section of the Coast Road are now complete, and works are underway beside the road to add top soil to the batter beside the Mackays wetland. Silt fences are an important last in a line of environmental controls used on the project, and help prevent silt from construction runoff that enters streams and waterways.

North of Bridge 2, which is the bridge that will provide access under the new motorway for some Paekākāriki residents, works to replace liquefaction prone material with more stable material is now complete and construction of the headwalls for a large culvert is underway.

Batter stabilisation and topsoil works

Batter stabilisation and topsoil works underway beside a section of Coast Road with silt fencing in place to silt from construction runoff travelling into streams and waterways.

Bridge 2

Liquefaction treatment works complete beside Bridge 2 at Paekākāriki.

Wainui Saddle area

Through the Wainui Saddle area, soil nailing, and stabilisation of crestal cuts and slopes continues. Bulk earthworks in this area are being scaled back for the winter works programme.

Soil nailing works

Soil nailing works underway to stabilise a crestal cut.

Cut benching

‘Cut benching’ refers to the different steps or benches that are cut into the hillside.

Earthworks for two further sections of Te Puka Stream are now underway. Teams are also working on a further three sections of the new Horokiri stream bed.

Horokiri stream bed

Rock placement underway on a further section of Horokiri stream bed.

The first two concrete deck pours are now complete for Bridge 6, which crosses over Horokiri Stream, near Battle Hill Farm Forest Park. A huge amount of reinforcing steel is required for the bridges, which is part of the seismic design and built in resilience for the new motorway.

Base slab reinforcing and the first concrete pour is also complete for Bridge 11 near Paekākāriki Hill Road. As is the case with every concrete structure on the Transmission Gully project, the steel reinforcing work is complex and takes time to tie together; like very tricky and cumbersome macramé!

Bridge 6

Bridge 6 showing the first deck pour complete and reinforcing works complete ahead of the second pour.

Steel reinforcing work

The complex steel reinforcing work adds strength to the structures as part of the seismic design for the new motorway.

State Highway 58 (SH58)

At Lanes Flat, Pauatahanui, work is well underway on the bridges that make up the State Highway 58 Interchange, as well as ongoing bulk earthworks through this area.  Construction of the new section of road, which will become the new route for State Highway 58, is progressing well and is now visible beside our Lanes Flat site office in Pauatahanui. To complete the interchange, towards the end of this year, traffic will be switched from the existing State Highway 58 road onto this new section of road.

SH58 Interchange bridges

Image showing works underway on the four bridges that make up the SH58 Interchange.

Bridge 15

Construction team working on a reinforced earth wall for Bridge 15 over Pauatahanui Stream.

Whitby and Belmont Regional Park

Through this area, teams are focussed on preparing for reduced earthworks over winter, by covering many areas with a special layer of capping material to protect the pre-pavement road level and ensure it is fully stabilised in wet weather. Some small scale earthworks, such as culverts, stream diversion works, and erosion and sediment controls, will continue through the winter months.  Bulk earthworks will be scaled back because drier weather is needed for this type of activity in the clayey and silty material that is present through this area.

James Cook Interchange

Works underway at the site of the James Cook Interchange, located near Whitby.

Bulk earthworks

Looking south over bulk earthworks underway towards Belmont Regional Park.

Cannons Creek bridge

Cannons Creek gully works

View from the Northern side of the Cannons Creek gully of works underway at the bridge’s launching yard.

Good progress continues with the sections of steel girders for the first launch phase being tied together. A special launching nose is set to arrive in the middle of the year. It will be connected to the completed sections of the girders, ready to guide this section of bridge over the gully later in the year.

Concrete pouring for the two pier foundations is also well underway, with seven of 11 pours complete for Pier 1, and six of eight pours complete for Pier 2.

The steel reinforcing for these piers is impressive, with some innovative thinking needed to build and install the cages in a very confined area at the base of the bridge.

Cannons Creek bridge’s steel girders

View of the Cannons Creek bridge’s huge steel girders being tied together onsite.

Pier 1

View looking over Pier 1’s foundation showing the concrete in place and the huge steel reinforcing in the centre.

Pier 2

Looking across to Pier 2 with concrete pours for the foundation nearly complete.

State Highway 1 – Linden, Tawa

At the southern end of the project, construction of the bridges through this area is progressing well, and road users can now see the changes as they drive through the area.

On Kenepuru Drive, the entrance to the North City Tenpin bowling alley has been changed so that our construction teams can prepare for construction of the connection between the bridge and the roundabout. North City 10 Pin are still open for business and would love to see you.

What’s coming up

With daylight hours fading and winter fast approaching, we’re getting ready to move into our winter works programme for the project, to be ready for the next bulk earthworks season that will start in October 2018.

Our focus from June to September will be on:

  • ongoing planting of native trees and shrubs
  • installing and monitoring environmental controls
  • continuing with complex culvert installations and stream diversions
  • continuing construction works on the project’s remaining structures.

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Mobile visitor centre on the move

Mobile visitor centre

Transmission Gully motorway mural by Porirua graffiti artist, Anthony (Antz) June.

The Transmission Gully motorway mobile visitor centre has now moved to Mana’s Dolly Varden Beach. Located in the carpark next to the Mana overbridge, the visitor centre will be open to the public, Monday to Friday, from 8.00am – 4.30pm.

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Lizards welcomed home


One of the lizards enjoying the sunshine after being released to its new habitat.

Last month, three species of lizard were given two special whakapainga (blessings) by Kaumātua of two iwi, before being released to a pest-protected home in the hills near Paekākāriki, overlooking Kāpiti Island.

The copper skinks, common geckos and brown skinks, were gathered from a section of the route of the Transmission Gully motorway before construction began in 2015 and have been housed at Ngā Manu Nature Reserve near Waikanae since their capture.  Now that the way is clear for their return, the lizards have been released back to newly created habitats, located outside of the active construction site.

Project staff and partners worked over two days, to firstly measure, weigh and tag the lizards, and then transport them to an area of special ‘predator-free’ rock piles, designed by PhD student Zoey Lennon. Zoey says the rock piles provide an ideal home for the lizards.

“As part of my thesis work, I designed specially sized boulder fields, that allow the lizards to access their new habitat, but ensure predators such as rats and mice, can’t get in,” says Zoey.

The newly created habitats the lizards were released to are located outside of the Transmission Gully motorway project's active construction site. The area was cleared of predators before the lizards were released in April. Pest control in the area continues.

To find out more about the lizard release, check out our interview series with the wider team.

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Innovative technology will increase safety for workers on site

The Transmission Gully project is leading the way in safety for workers on site through the use of innovative technology that is designed to prevent collisions between machinery and ground staff on construction sites.

Wellington Gateway Partnership CEO Sergio Mejia says innovative technology being trialled on the Transmission Gully project will add another layer of protection for workers on the job.

“The formation of a public-private partnership to deliver the Transmission Gully motorway is a hallmark of the many positive benefits that have been made available to us,” says Sergio.

The new motorway site has provided an opportunity for the Hunter Safety Lab and project teams to work together to do some field testing of the Infrared Retro-reflector Identification System (IRIS) Detect product, which is aimed at keeping workers safe.

IRIS Detect is a type of pedestrian detection technology designed to prevent collisions between machinery and ground staff on construction sites. Sensors detect the reflective strip found on high-visibility safety vests, meaning everyone on site, including visitors and subcontractors, are detectable by default.

IRIS Detect sensors

IRIS Detect sensors mounted on the back of machinery detect ground staff and send an alert to the operator.

Hunter Safety Lab Founder, David Grove, says IRIS Detect has some unique benefits over traditional pedestrian detection systems.

“IRIS Detect recognises the reflector strips within high-vis vests, meaning that the system conforms to the user, or in this case, anyone who is wearing a high-vis vest. The most significant advantage of this technology over most other industrial pedestrian detection systems is that it doesn’t require ground staff to carry an electronic tag or change their behaviour in any way,” says David.

Construction Project Director, Boyd Knights, explains that as the Transmission Gully motorway is a very busy construction site with over 600 people and over 200 items of machinery at work, IRIS Detect will help to further improve site safety.

“The potential for interaction between people and machinery is ever present. If we can add another layer of protection in managing our critical hazards, in a practical way, then we should explore those options,” says Boyd.

Sensors mounted on machinery continuously emit pulses of non-visible light into blind spots around the machine. The driver receives an audio-visual alert when someone is detected in the blind spot.

IRIS Detect sensors

Field trials were carried out at the Transmission Gully motorway site on an articulated mobile crane. These cranes are often used in areas where there are staff on foot in the immediate area, and the machine is often reversing as part of its normal activities.

“Due to the success of the trials to date, we’re now considering the use of this technology on two of our small ‘Telehandlers’ which are pieces of equipment often used in laydown areas for loading and unloading trucks, and where a significant amount of reversing is involved.

“As part of our current Health and Safety practices, all workers are removed from machinery operating zones to eliminate interaction, however this technology would give another layer of protection to help the operator by notifying them of workers on foot who may have unintentionally wandered into the operating area or into one of their blind spots,” says Boyd.

“It’s important that we promote and support this sort of technology. We’re always looking at ways to improve what we do, and if, as an industry, we don’t support development of innovation, we are the poorer for it,” says Sergio.

Check out Hunter Safety Lab’s video showing a controlled field trial of the IRIS Detect technology onsite and also outside of the Transmission Gully motorway project's active construction site.