Source: New Zealand Transport Agency
Waka Kotahi NZ Transport Agency says the completion of a huge amount of work on the Transmission Gully motorway over summer has brought the road to a stage where Waka Kotahi is confident that it is safe for public use, and it has instructed the contractor to open the road to traffic before the end of this month.
To support the road opening sooner than would otherwise be possible Waka Kotahi has agreed to defer a number of quality assurance tests that are required under the contract, allowing them to be finished after the road is open. Waka Kotahi says none of the deferred tests will compromise public safety, as they relate to ensuring the long-term quality of the road.
Waka Kotahi Board Chair Sir Brian Roche says the decision to formally instruct WGP to open the road to traffic by the end of March reflects the pragmatic and considered approach Waka Kotahi has taken in its negotiations with the contracted parties.
“Waka Kotahi has been committed to finding a pragmatic solution that ensures we are doing everything we can to open a safe motorway, while meeting the public expectations for it to be open for use as soon as possible and to ensure we safeguard good use of public money,” Mr Roche says.
Waka Kotahi General Manager Transport Services Brett Gliddon says complex negotiations are continuing with the parties we’ve contracted to build, manage and maintain the road.
“However, we are confident the motorway is now in a fit state to open, which is why we have issued this instruction, while we continue with negotiations,” says Mr Gliddon.
“We have not been prepared to compromise on the road’s safety, however all of the critical safety assurance tests have now been completed to a standard that gives us confidence the road will be a safe, reliable route for motorists between Wellington and the rest of the North Island.
“The road was not ready in December when we had wanted to open it ahead of the busy holiday season, which was extremely disappointing. However, we acknowledge the builder has worked extremely hard over summer, and while there are still a number of quality assurance tests in the original contract that have not been finished and there is paperwork that still needs to be completed, we don’t believe they are critical factors that should prevent traffic from being able to use the road.
“Now that we have deferred these quality assurance requirements, we believe there is nothing substantial that can’t be finished by the end of March, which would prevent the road from opening. We have told Wellington Gateway Partnership (WGP) that we expect the road to be opened as soon as possible and that responsibility now sits with them.”
Under the Public Private Partnership (PPP) the contractor, WGP is responsible for determining when the road can be opened. Subsequent to the COVID-19 outbreak in August 2021, Waka Kotahi, WGP, CPB HEB and Ventia have been negotiating an early access arrangement, which would allow motorists to use the road before all of the Road Opening Completion requirements set out in the contract have been met. As agreement has not been able to be reached, Waka Kotahi has now formally directed WGP as the contractor to allow the public to use the road before the end of March 2022.
Several key requirements will need to be met for the road to be opened by the end of March, including a final pre-opening safety inspection.
Waka Kotahi is working hard with all the parties including Greater Wellington Regional Council and territorial authorities so that the remaining resource consent tasks are resolved prior to road opening.
Mr Gliddon says while pavement and road surface tests are among the quality assurance tests which have not been met, expert advice is that the road is safe for use and there are benefits to allowing the road surface to be trafficked to bed it in before winter. CPB HEB will continue to address any road surface issues over the next year as the chipseal continues to bed in.
As with any motorway opening, Waka Kotahi will not be announcing a specific opening time for the road, in order to prevent any queuing which could cause safety and congestion issues.
“When people drive Transmission Gully we know they’ll enjoy the stunning views through the Wainui Saddle and appreciate the scale of the complex engineering required to build this road through some of the most challenging terrain in New Zealand. Most importantly, it is a safer and more resilient route than the coastal route people are currently using.”
As the PPP contractor for Transmission Gully, WGP has subcontracted CPB HEB to undertake the motorway’s design and construction, and Ventia to operate and maintain the motorway for 25 years, after which it will be handed over to Waka Kotahi at an agreed standard.
Building Transmission Gully – key facts:
- Transmission Gully is one of the largest transport infrastructure projects in New Zealand.
- 27 kilometres of motorway, with four new interchanges, have been built through geologically and geotechnically challenging and steep terrain with constrained and difficult access, requiring construction of 25 major structures (bridges and large culverts).
- All structures have been built to withstand a 1 in 2500-year earthquake. The largest structure, Te Ara a Toa is 230 metres long and 60 metres high.
- Cuts of up to 70 metres were made through the Wainui Saddle, which also has the Ohariu fault line running through it. Pouāwhā Wainui Saddle has been lowered to a final crest height of 253 metres above sea level.
- More than 11 million cubic metres of earth has been moved, the largest volume of earthworks ever undertaken on a roading project in New Zealand. With well over half of the catchment draining into the ecologically significant Porirua harbour, the earthworks required extensive environmental controls including more than 100 sediment retention ponds.
- The road runs through valleys criss-crossed with streams. As part of the project, around seven kilometres of streams have had to be diverted, and approximately 27 kilometres of streams are being restored, with planting along the banks to provide shade, reduce water temperatures, and improve the natural habitat for stream life.
- The Transmission Gully project includes one of the largest native planting programmes undertaken in New Zealand as part of a construction contract, with more than 550 hectares of ecological mitigation areas being either retired from grazing or revegetated.
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