New Images: Behind the Scenes at Transmission Gully

Construction of Wellington’s troubled Transmission Gully highway is now more than 85 percent complete and NZTA is confident it will open next September.

The 27 km road has suffered delays, lost costs and is now undergoing a government-ordered overhaul.

It was meant to be open in April 2020, then delayed before Christmas this year, and is now due to open in September 2021.

The project is being built through a public-private partnership, the Wellington Gateway Partnership (WGP), with CPB Contractors and HEB Construction subcontracted to carry out design and construction.

The total cost of the road has risen to $ 1.25 billion after the NZTA rescued contractors twice due to issues such as the Kaikōura earthquake, extreme weather events, and the Covid-19 pandemic.

But the CEO of the Wellington Gateway Partnership, Sergio Mejía, said today that he could see the light at the end of the tunnel and was confident that the road would open next September.

“I am sure we are going to hit the mark, we are fully committed and we are on schedule.”

Mejia said he was proud of the team working on the four-lane highway from Mackays Crossing to Linden.

“Regardless of how difficult things are and have been, the guys keep going and keep working.

There will be some activity at the site over Christmas, but crews will take a break before returning to go “full blast,” Mejía said.

“You will see crews laying the pavement and the road will be largely completed by the middle of next year.”

Andy Thackwray, Senior Project Execution Manager for Waka Kotahi NZTA, acknowledged that Wellington residents have waited a long time for the road to open.

When asked how the transportation agency would rebuild public trust in the project, Thackwray said: “It is a very difficult and complex project to deliver, we are on track to open next year and we will move on.”

Running north to south, the first part of the lineup is where there is the most work to be done.

The largest excavation cuts have been made at this end of the road, where the Wainui Saddle is located.

The cuts here are up to 70 m deep, resulting in the removal of more than 865,000 cubic meters of earth that has been moved.

That amount is almost three times the volume of Wellington’s Sky Stadium.

During the Kaikōura earthquake, a landslide occurred in this area, which turned out to be just one of many setbacks to the construction of Transmission Gully.

The face of the earth, which rises around where the road will finally be, is covered by 22,700 square meters of specialized concrete.

Lots of pipes are on the side of the highway corridor, which is bumpy and difficult to pass.

It is clear that this road was nowhere near being open for Christmas.

Further on from the saddle the hills start to disappear and the site becomes flatter, but that in no way makes construction easier.

The ground here is swampy and wet, so I had to remove a lot of it and replace it with more stable material.

Mountains of gravel have piled up on the side of the road.

The gravel will eventually mix with cement and be layered over the road. Around 780,000 tonnes of crushed rock is needed for the construction of the pavement at Transmission Gully.

It is a truck town ahead at the Waitangirua junction.

Right now, there are 57 dump trucks working on the site to move the pavement material to where it is needed.

Farmland surrounds the alignment and small access roads have been constructed under the main Transmission Gully route to maintain accessibility.

Up to 7 km of local streams have been diverted and 31,000 fish have been caught and transferred by environmentalists to ensure they are not disturbed by construction work.

It is expected that in less than 10 years after the opening of the new highway, the quality of the water and the surrounding environment will be in better condition than before the construction of the highway.

Further down the road is the largest single structure in the project, which is the bridge over Cannons Creek, called Te Ara a Toa.

The bridge has four lanes and is 60 meters above the stream below.

It took six years to build the 230-meter-long bridge, the base of which is insulated to reduce movement when the surrounding land is displaced in an earthquake.

More than 9 million work hours have been completed on the project to date and there are currently 570 people working on the site.

When Transmission Gully opens, approximately 25,000 vehicles are expected to use it each day.