The TGP is a four-lane, 27-kilometre motorway that will run from Mackays Crossing at Paekākāriki to Linden. Originally comprising part of the Wellington Northern Corridor of the Roads of National Significance (RONS) programme, the TG motorway will act as a catalyst for economic growth in the Wellington region by bypassing the existing coastal route and thereby increasing road safety and improving network reliability with high levels of seismic resilience.
Key benefits of the TGP include:
• Providing an alternate and resilient transport corridor to and from Wellington;
• Reduce travel time, variability and congestion for motorists on State Highway 1 and the existing coastal route, and improve safety within communities like Porirua by significantly reducing through traffic;
• Significantly reduce the number of fatal and serious injury crashes, and provide a more reliable and safer journey for all transport users; and
• Facilitate economic development within the region and nationally.
TG is the first motorway in New Zealand to be delivered on behalf of the New Zealand Government under a PPP using the availability PPP model (but was the third availability PPP project at that time in New Zealand). In July 2014, Waka Kotahi signed a PPP contract with the Wellington Gateway Partnership (WGP) (a private consortium of construction contractors, operations and maintenance providers, and financiers) to design, construct, finance, and then operate and maintain the new motorway for 25 years following the construction period.
Under an availability PPP, whole-of-life services are purchased under a single contract with annual service payments made by Waka Kotahi to WGP based on availability and performance of the TG motorway. These annual service payments only commence once the TG motorway is certified as ready for operational use. During the 25-year services period, WGP is required to maintain the TG road to defined performance standards and, at the end of the services period, hand back the asset to Waka Kotahi in a certified, fit-for-purpose condition.
TG is a highly complex project, with difficult and steep terrain requiring large-scale earthworks during construction of the project, together with significant seismic and geotechnical risk factors. The scope of project works includes:
• The design, finance and construction of a 27-kilometre long expressway-standard motorway just north of Wellington, with a 25-year operations and maintenance contract;
• The design and delivery of 25 bridges and culverts (the largest of these structures, the Cannons Creek Bridge, will stretch 230 metres in length and sit 60 metres above the valley floor), four interchanges and two connecting link roads, and the movement of 10.2 million cubic metres of earth during construction of the project; and.
• More than 534 hectares of ecological mitigation areas and 27-kilometre of stream remediation, restoring native landscapes and mitigating the sedimentation effects of the project on waterways.
The TG motorway is scheduled to be open for traffic in September 2021.