Seven months after Cyclone Gabrielle, Auckland Transport, KiwiRail and Downer have completed work on the major slip that closed Tahekeroa Road and fell on the main trunk railway north of Helensville.
The area surrounding the slip is vital to the community; it connects rural residents and farm operations with State Highway 16 and is a key strategic freight route between Auckland and Northland.
Auckland Transport Flood Recovery Manager Murray Burt says the repair is a major milestone for flood recovery in Auckland, and involved a strong collaborative effort between AT, KiwiRail and Downer Construction to complete.
“The 390-metre slip repair was a tricky and complex piece of work, involving more than eight contractors and subcontractors working in difficult conditions over the winter months to get the job done. An initial bund was built to provide protection for contractors who then rebuilt 120 metres of rail line and constructed a permanent bund to protect against future weather events.”
Contractors removed around 35,000 cubic metres of earth from the slip, 95 per cent of which was re-used on the site to construct the new earth structures and reshape the ground surface. This has saved the project several million dollars in tip fees, cartage, and the cost for imported fill. It also saved the surrounding road from excessive and ongoing damage, minimised traffic in the area and reduced the build time by about 10 weeks.
“We’re proud of the work we have done together and what has been accomplished,” says KiwiRail Project Manager, Richard Hattaway.
“The new road is raised four metres, with large culverts that run underneath into a basin area, and another set of culverts under the rail line. Not only will this enable water to flow quickly away from the site, if there is another slip the raised road will act as a barrier and the basin will be able to capture slip material before it reaches the rail line.”
Downer Construction Manager Ben Parsonage says his team is proud to have contributed to this amazing feat of engineering.
“Our team worked tiresomely through a very wet winter to ensure Tahekeroa Road and the critical rail link was reinstated as quickly as possible. We understand how vital this corridor is to the local community and the significance of the freight link between Tāmaki Makaurau and Te Tai Tokerau. We are proud to have played our part.”
Some works have been completed on private land and AT, KiwiRail and Downer would like to acknowledge and thank the owners –who generously granted access and goodwill to support the project teams.
Tahekeroa Road is now open to traffic, however KiwiRail's North Auckland Line (NAL) rail corridor remains closed until work is completed on other significant damage sites between Helensville and Whangarei.