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The hole where SH25a once stood now measures around 110 metres across. Photo: WAKA KOTAHI

State Highway 25a fix ‘may take a year’

It will be around nine to 12 months before State Highway 25A is fully re-opened in the Coromandel, Waka Kotahi NZ Transport Agency said. 

Regional Manager of Infrastructure Jo Wilton said a solution was still being worked on.

“There are three main options for reinstating this highway. One – we build a bridge replacing the lost section of road; two – we build a deviation which bypasses the slip site; three – we build a retaining wall and effectively rebuild the road from the ground up,” Ms Wilton said.

“We don’t know which option is most feasible yet. The right solution cannot be established until the geotech work is complete. We know the rebuild must be resilient and as timely as possible. We understand how critical this highway is for Coromandel residents, businesses, and visitors,” Ms Wilton said.

 There has been some further deterioration of the slip site following Cyclone Gabrielle. Some cracks across the road near each edge of the slip have widened, but there has been no further movement at this stage.

“The Hikuai side of the slip is high and possibly unstable. Assessment of the stability of this slope is underway,” Ms Wilton said. 

“The next step is to construct a temporary track, to allow access for a geotech drilling rig up to the site of a potential deviation above the slip area. We also need to form another access track to the base of the slip where a retaining wall could be founded, but the ground is too wet to do this yet. Until we can get a rig in – we can’t get significant testing done.”

Ms Wilton said the tracks would likely be in place in approximately two weeks, subject to weather. 

SH25A was closed on January 27, following the formation of deep cracks in the road after Ex-Cyclone Hale. The cracked section of the road at the summit slipped away during the Auckland Anniversary storm event.