State Highway 1 over the Brynderwyn Hills is expected to reopen at the end of June, Waka Kotahi says, following a delay caused by an active slip.
The major road connecting Auckland with Northland was forced to close for critical road restoration works following Cyclone Gabrielle last year. It was due to reopen on May 13 but this was pushed back due to two significant slips on April 26 and April 30, the New Zealand Transport Agency’s manager of infrastructure delivery, Mark Kinvig, said.
“We know how difficult the highway closure is on local businesses and communities,” he said.
“Our priority has been to undertake geotechnical and safety assessments to determine the best option for stabilising the hillside and getting State Highway 1 Brynderwyn Hills open as quickly as possible.”
Reopening is conditional on ground stability
Kinvig said plans were in place to reopen the road at the end of June but “if there is a significant amount of unexpected rain, or further instability is found, that could delay the reopening timing”.
“However we are committed to completing these vital recovery works as quickly as possible to ensure a safe and reliable SH1 Brynderwyn Hills for the short to medium term,” he said.
Excavation has already started, with operators working from a platform at the top of the ridge to remove soil, reducing the likelihood of further slips.
Up to 55,000 cubic metres of earth will be excavated to stabilise the site where the two slips occurred at Kauri Tree Corner.
“Our team is working seven days a week, where weather allows, to get the road open,” Kinvig said.
“We are maximising the number of trucks, diggers and workers on site to ensure the soil removal is a continuous operation, utilising daylight hours, to get it clear.”
The remaining planned works — including drainage and pavement works — were on track and being worked on in tandem.
Kinvig said contingency plans were in place for poor weather, while ground conditions were being actively monitored by staff and GPS sensors.
There was a risk of further slips until the stabilisation work was completed.
Three official detour routes – SH12/SH14; Paparoa Oakleigh Rd; and Cove Rd – were being monitored while the closure was in place.
“We thank everyone for their patience and remind people to drive safely when using the three detour routes to access Northland.”
‘Not a surprise’
In a statement, National Road Carriers Association CEO Justin Tighe-Umbers said said the delayed reopening of SH1 Brynderwyns due to the recent slips was “not a surprise”.
Tighe-Umbers said the diversion routes used by road transport operators add between 60 to 140 kilometres to journeys – and the increased costs were being passed on to customers.
“This delay is another reminder of the urgency needed to replace this vulnerable section of State Highway 1,” he said.