In April 2017, a major landslip from the Tararua ranges cascaded down on State Highway 3 in New Zealand’s lower North Island, cutting off the main link between Manawatū and Hawkes Bay. Safety concerns about further landslips caused the critical strategic trading route through the Manawatū Gorge to be closed indefinitely.
Since then, travellers have had to take alternative routes along Saddle Rd and Pahiatua Track: both steep and windy journeys that are frequently subject to traffic delays and safety concerns.
Providing a safe, resilient and efficient connection to replace the route through the Manawatū Gorge is an urgent priority; not only for the safety and comfort of travellers, but for the prosperity of the region as a whole. State Highway 3 is an important strategic route for freight, and small towns along the closed route have suffered due to lack of visitors.
In mid-2019, Waka Kotahi New Zealand Transport Agency (the Transport Agency) engaged an Alliance comprising itself and Aurecon, Fulton Hogan, HEB Construction Limited and WSP to consent, design and build the 11.5km replacement route, which will take motorists from Woodville to Ashhurst and over the Ruahine range. The rural state highway will provide four lanes of traffic, six bridges and support active transport modes through a shared use path.
Aurecon is providing planning, consenting, engineering design, digital and construction phase services, as well as advisory services. Our resilient and safe design solution, plus our innovative approach to reducing consenting risk were a key factor in securing the contract.
The new road is due for completion by the end of 2024.
We developed a 3D digital model for the entire project, including a fly-through during the tender stage which assisted the Transport Agency and Iwi to understand our thinking and enabled them to see first-hand how the new highway will integrate into its environmental and cultural context. Virtual Reality (VR) has also been an invaluable tool in conversations with both iwi and the Transport Agency.
Within the Alliance, our design and construction teams have made use of VR to help them understand how key design elements will integrate and fit in real life – for example, the complex interaction between bridges, earthworks, drainage and cultural expression design elements.
As part of the Alliance, Aurecon is working in partnership with four different Iwi (Ngāti Raukawa, Rangitāne o Manawatū, Rangitāne o Tamaki nui a Rua and Ngāti Kahungunu ki Tāmaki nui a Rua) to develop the consents and design for the new highway, ensuring the taonga they value are protected, and the area’s unique heritage is celebrated. Importantly, Iwi are partners within the Alliance in governance roles and working in the Alliance to develop the consent conditions for statutory approvals. This partnership approach is the first of its kind in New Zealand.
As project partners, Iwi will be heavily involved during the construction of the new highway as well, through apprenticeships for youth and business opportunities for local Māori SMEs (small to medium enterprises). The Alliance is working with Iwi to create legacy opportunities that support local Māori/Pasifika individuals, families and businesses to grow long after the new road is complete.
Manawatū Gorge is an area of outstanding natural beauty, with a challenging environment and topography. Several sites of ecological and cultural significance are located along the new route, including remnant indigenous old growth forests and ancient native matai trees. Aurecon has worked with WSP to develop a road alignment that treads lightly and blends into the rural landscape and minimises impacts on these sensitive environments.
We extended the length of an eco-bridge and optimised the road alignment to avoid a sensitive gully, eliminating the need to clear any heritage trees and minimising impacts on surrounding stakeholders. Our design reconnects the community to this valuable place with a network of walkways that weave around the restored Raupō wetlands below the eco-bridge.
The Manawatū region is highly seismic with active fault lines crossing the new highway at multiple points. Our deep understanding of the complex geology, seismic design and earthworks design has enabled our team to develop a resilient solution for the new highway and the bridges, and earthworks cut and fill embankments along it.
We used digital technology to help identify how we could make it easier and safer for maintenance crews to access and maintain the new highway in the future. Through our Safety in Design processes, VR allowed us to see from a real-life perspective how people and elements will interact in the live road corridor – helping us select the best locations for things like pullover areas and culvert access for safe maintenance.
The indefinite closure of SH3 through the Manawatū Gorge two and a half years ago has had a significant impact on the local community and economy, so the new route needs to be open as soon as possible.
Aurecon worked with the other Alliance partners to develop a programme that allows flexibility in the consenting and property acquisition process, while allowing a fast start on some early works. We de-risked the time taken for securing statutory approvals by shifting the road alignment to minimise impacts on stakeholders and the environment, and adding design enhancements which create a positive legacy for the community. Importantly, we are developing consent applications in partnership with Iwi, to ensure they are comfortable with the conditions in them.
As well as the creation of a safe, efficient and resilient transport connection, the construction of Te Ahu a Turanga: Manawatū Tararua Highway will provide an important economic boost to the Manawatū region and lower North Island. The Alliance has set targets for the employment of local people and will partner with local training providers to deliver apprenticeship programmes for youth. Iwi and local businesses will gain from the opportunity to work on a project of this scale and complexity.