SH7 Sylvia Flats west of Hanmer turnoff, realignment away from river to protect highway


Waka Kotahi NZ Transport Agency has begun a major realignment of 700 metres of highway on SH7, west of the Hanmer Springs turnoff. Establishment work on site started this week with earthworks from next week.

“The realignment is needed as the Lewis River is cutting into the highway at Sylvia Flats, near the Boyle River, and eventually will undermine it, threatening the route,” says Colin MacKay, Portfolio Manager for the Transport Agency. “We need to realign this road to ensure it is safely away from the river and ensure this key state highway linking the east and west coasts and Nelson/Marlborough remains resilient and reliable for the future.”

The work will continue throughout summer until May 2020. Road users will have to slow down near the work site while crews, trucks and machinery are on the highway, Monday to Saturday inclusive, 7am to 7pm.

The overall cost of the project is around $3 million. The Transport Agency has been working closely with the Department of Conservation since this project was proposed as the area is part of the public conservation lands and resource consents have been required for all construction activities.

The area of road being realigned is three kilometres past the Boyle River, on the west side of the Hanmer Springs turnoff and Island Hills.

State Highway 7 (SH7) is a key freight and tourist route between the West Coast and Canterbury, Nelson/ Tasman and Canterbury and Picton and Christchurch. It runs through the Lewis Pass National Reserve and public conservation lands. In the event of SH1 via Kaikōura being closed, the Lewis Pass is the only road link between Picton and the rest of the South Island.

In coming months road users on SH7 may notice crews:

  • Shifting felled trees and vegetation. All beech tree removal is being done with guidance from the Department of Conservation and to ensure nesting native birds are not affected. All of the felled trees will be stockpiled, either to be mulched or to be placed over the old road alignment at the completion of the project to re-establish a local habitat and vegetation area.
  • Taking away material from the site for the new realignment. About 70,000 cubic metres of soil and rocks will be removed, more than 8,000 truckloads.
  • Working on earthworks for much of the summer, constructing the new alignment.

Surfacing the new road, if weather permits, this summer/autumn. If the weather is wet, sealing may be completed in the summer of 2020/21.

Sylvia Flat Lewis Pass beech trees falling into Lewis River

Sylvia Flat Lewis Pass beech trees falling into Lewis River – June 2018.

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