Protecting the Lewis Pass highway from river erosion, work timed to avoid nesting season

2 MinutesBy NZ Trucking magazineJuly 18, 2018

In preparation for a $2 million realignment of the South Island‘s Lewis Pass highway (SH7), NZ Transport Agency crews will be clearing a stand of trees this week. The road construction work will take place over the 2018/19 summer roadwork season.

The Department of Conservation (DOC) is working closely with NZTA to minimise the number of beech trees which need to be removed and to protect the wildlife habitat by ensuring the tree felling is well ahead of bird nesting season in September.

The New Zealand native falcon/karearea nests in the trees in September so no tree felling can occur once the birds are nesting.

This photo, taken with a drone, shows how the river is already eating into the side of the highway and the border of beech trees lining the river.

State Highway 7 is a key freight and tourist route between the West Coast and Canterbury, Nelson/ Tasman and Canterbury and Picton and Christchurch. It also runs through the Lewis Pass Scenic Reserve and national parks. In the event of SH1 via Kaikoura being closed, the Lewis Pass is the only road link between Picton and the rest of the South Island.

DOC North Canterbury District Office operations manager Kingsley Timpson said the department was working closely with NZTA on the project to ensure the natural values of the important Lewis Pass Scenic Reserve were protected during the realignment of State Highway 7.

NZTA senior network manager Andrew Crofts said the realignment was necessary as the Lewis River was cutting into the highway at Sylvia Flat, near the Boyle River, and would eventually undermine it, threatening the route.

“We need to realign 300 to 400 metres of road to ensure it is safely away from the river,” he said.

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

Drivers may experience short five-minute delays through this area this week around the crews.