Higgins Construction Nelson

CATEGORY 2: Projects with a value between $1 million and $10 million

Correcting a very dangerous part of SH1

The Dashwood Overbridge Realignment project transformed a dangerous section of State Highway 1 in the Marlborough region north of Seddon. The New Zealand Transport Agency awarded this important rail bridge realignment project to Higgins. The old Dashwood Overbridge, built in 1932, had been the site of a number of crashes over recent years. The layout of the road on either side of the bridge, tight curves and difficult approach to the overbridge, had caused problems for all vehicles, particularly trucks. The remedial work involved 16 months of construction work; two kilometres of CATEGORY realignment; removing several tight curves 2 FINALIST on either side of a road/rail bridge; construction of a new wider, and seismically resilient, road/rail bridge; and an improved approach to the bridge. The significance for this project was constructing the tunnel and approaches while the main trunk line was still operating. Also challenging were requirements around seasonal working and causing minimal disruption/ impact to road users, local residents and the environment. This project involved about 16 months of construction work and extensive investigations, planning, design, and consultation. Some 10,000 truck loads moved 148,700 cubic metres of earth during the works.

The biggest project challenge was constructing the 54-metre long Armco Overbridge while the main trunk line was still operating. The second challenge to the project was demolishing the existing (85 year old bridge) as Higgins had a limited 30-hour window where the line was closed.

“This project is a wonderful achievement for the region and one that Higgins is very proud to have constructed,” says the company.

The project was completed in April 2015 safely and on time, causing minimal disruption to road users, trains and local stakeholders, and ahead of schedule and under budget.

The client’s base estimate for the contract was $6,200,850, but it was completed for $5,970,014.

“All this was achieved by building on our previous experience of working on similar major national projects and utilising the extensive understanding of local conditions from staff at our Nelson branch.” l