In April 2017, severe weather caused major slips on State Highway 3 (SH3) through the Manawatū Gorge. This is a major route connecting the Manawatū, Tararua District, Hawke’s Bay and northern Wairarapa.
Credit: Waka Kotahi NZ Transport Agency
The road was closed, and traffic was diverted via local roads which are not of State Highway standard, increasing accident risk and travel times. A safe, resilient and efficient replacement road was required.
Waka Kotahi - the Waka Kotahi NZ Transport Agency’ proposed a new 11.5km route connecting with State Highway 57 south of Ashhurst and SH3 west of Woodville.
The proposed route presented several challenges: it travelled through high-value and sensitive ecological areas, an operating wind farm, and crossed multiple seismic faults.
Minimising impacts on ecology, windfarm operations and maintenance and managing landowner and stakeholder expectations were essential to this project. Together with our Alliance partners Fulton Hogan, HEB Construction and Aurecon, we proposed a route that was partially outside the original Notice of Requirement designation to minimise impact on the ecology of the area, while also avoiding the decommissioning of any wind turbines. Our team’s design incorporates improvements to make the road more resilient during earthquakes and slips, provides ecological enhancements and develops new community facilities.
The new road will have a traffic lane and a crawler lane in each direction over most of the route, separated by a median strip and new bridge crossing the Manawatū River. It includes separated walking and cycling facilities.
Currently our team is working with iwi partners Rangitāne o Manawatū, Rangitāne o Tamaki Nui-a-Rua, Ngāti Kahungunu and Ngāti Raukawa to refine the road’s design.
WSP is providing roading, structural and geotechnical design, drainage design, hydrological modelling, planning and consenting, road lighting and electrical expertise.
WSP global expertise will be used for specialised disciplines such as special structures and wind modelling.