Transmission Gully builder will not achieve pre-Christmas opening


Waka Kotahi NZ Transport Agency says Wellington Gateway Partnership (WGP) and CPB HEB Joint Venture, the builder contracted to deliver the Transmission Gully project, have run out of time to complete all of the tasks necessary for the road to open in time for Christmas.

“We have been pushing very hard for the Transmission Gully motorway to open to the public as soon as possible and we made our expectations clear to WGP and CPB HEB that we wanted this to be before Christmas. With many outstanding issues yet to be addressed, tests to be met and consent tasks to complete, there is a lack of sufficient assurance that road opening pre-Christmas is achievable,” says Waka Kotahi Board Chair Sir Brian Roche.

“We are extremely disappointed that the road will not be open before the Christmas holidays. Like everyone else, we are frustrated by the delays and lack of certainty about when the road will be able to open and while we can’t yet say when it will be, we can be certain that it won’t be this year. It may in fact be some time before all the safety and quality assurance tests required in the contract are met,” Sir Brian says.

Waka Kotahi General Manager Transport Services Brett Gliddon says achieving a pre-Christmas opening has been dependent on the road’s builder, CPB HEB, meeting the contractually agreed requirements to ensure the road is safe for motorists and completed to a high standard. An Independent Reviewer was appointed by both Public Private Partnership (PPP) parties, Waka Kotahi and WGP, to check the tests have been met.

Under the terms of the PPP contract, road opening is decided by WGP and advice that the Independent Reviewer is satisfied that all safety and quality assurance tests have been met. Building a road that meets these tests is the responsibility of WGP and its subcontractor CPB HEB.

“Based on the information we have, and advice from the Independent Reviewer, we do not have sufficient assurance that all the tasks still needing to be finished to ensure the road is safe and reliable on an enduring basis, can be completed between now and Christmas,” Mr Gliddon says.

Out of 100 safety and quality assurance tests that need to be met before the road can safely and legally open, as at 10 December 2021 41 final test submissions have been received from CPB HEB, of which 34 have been accepted by the Independent Reviewer as meeting the required specifications.

Of the 45 consent tasks that need to be complete in order for the road to open – as at 3 December 2021, 17 have been completed, 26 are underway and have been progressed to varying degrees and two are not yet started. Some of these are well advanced and will be completed soon, however a fully functioning stormwater system, capable of treating road run-off water to the required standard must be operational for road opening.

“Waka Kotahi has been working with WGP and CPB HEB to determine how best to address some of the outstanding issues in order to get the road open to the public as quickly as possible while ensuring the enduring safety and quality of the road is not compromised,” Mr Gliddon says.

“An update will be provided once those discussions have concluded, and we have a clear way forward.”

The road was due to open by 27 September 2021, following an agreement for additional time and compensation due to delays caused by the Covid-19 lockdown in 2020. There was already significant risk that WGP and CPB HEB were not going to meet this date prior to the August 2021 lockdown.

Construction work has been progressing since the site was reopened after the August 2021 lockdown. Waka Kotahi is currently in commercial discussions to determine how much of the delay is due to the most recent lockdown and other Covid-19 restrictions, and the financial implications of this.

As the PPP contractor for Transmission Gully, WGP has subcontracted CPB HEB to undertake the motorway’s design and construction. Once the road is open the PPP contract will move into the service phase. Ventia will operate and maintain the motorway for 25 years, after which it will be handed over to Waka Kotahi at an agreed standard.

PPP agreements are a different model to what has been used for all previous roading projects in New Zealand.

“Transmission Gully is New Zealand’s first transport infrastructure project being delivered under a PPP. The terms of the contract are very strict, both for the build phase and the operation and maintenance of the road. This is how we ensure we are getting what we are paying for in terms of quality, safety and performance over the period of the contract. At the end of the 25-year operating period, the road passes to Waka Kotahi,” Mr Gliddon says.

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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