SH4 Raetihi to Wanganui reinstatement one step closer

3 MinutesBy NZ Trucking magazineMay 7, 2020

A new permanent road to connect Raetihi and Wanganui is a step closer, following a decision on the option to replace the section of State Highway 4 damaged in the October 2019 slip.

The NZ Transport Agency has selected the option after a rigorous assessment process that considered a range of different routes.

The chosen option to replace the damaged section of SH4 will cross a stabilised section of the Te Oreore slip and follow a similar path to the temporary road.

“We know how vital this road is to locals, travellers and freight, and it was important that we get this decision right,” regional transport systems manager Ross I‘Anson says.

“The road is in a difficult environment so any option would need to strengthen the highway‘s resilience so it can better withstand the challenges of the unique topography and severe weather events.”

I‘Anson says the assessment process considered a number of factors, including network resilience, resilience in the case of a major event like the October 2019 slip, cultural heritage, impact on property owners, how easy it would be to build, and the ability to protect the existing landscape, plants and animals.

“Through this process, we have selected the permanent route. A key aspect of this option is the improvements to ground stability that will be achieved by lowering the groundwater levels. By removing water, we expect that State Highway 4 will be more resilient against future slips.

“We would like to thank Atihau-Whanganui Incorporation and Ngati Rangi for their generosity and support throughout the process of building the temporary road and looking at options away from the existing road. We look forward to continuing to work alongside them as we move to the next phase,” I‘Anson says.

Further work on detailed design, resource consents and property discussions are underway. Work will begin soon to remove water using wells and pumps in the landslip area to improve ground stability. This is part of the preparation for construction, which is expected to start in the summer of 2021.

Meanwhile, work on resilience and remedial projects along SH4 is beginning to resume with strict health and safety protocols in line with alert level 3.