Near Fort Providence, NWT
Client – Government of Northwest Territories
Ruskin Construction Ltd. was contracted by the GNWT to construct a 1,045m long cable-stayed bridge spanning the Mackenzie River, near Fort Providence, NWT.
The Foundations Phase of the Deh Cho Bridge Project included the construction of two 500m temporary access trestles to access the eight subsurface cofferdam constructed footings. The trestles had to be installed and removed each season to allow for the spring ice flows, and the footings had to be pre-drilled to allow for the installation of a sheet pile cofferdams. Once the cofferdams had been installed, the excavation was completed to final depth. An average of 600m3 of tremie concrete was placed in each footing before the balance of the pier construction could begin. The work had to be executed throughout the year, including the winter season, with adjustments made to access during the spring freshet ice flow. Each pier was constructed from the work trestles, including double crane lifts to erect the delta frames for each pier. Ruskin produced over 10,000m3 of concrete on-site for the foundation of the Deh Cho Bridge.
The Superstructure Phase included the launching of 55 steel truss girders and the placement of 280 precast deck panels. This superstructure consists of approximately 3,775 tonnes of steel and 2,850 m3 of precast concrete. The main span is supported by a cable stay system that required a highly engineered work plan for adjustment and tensioning during installation due to the thermal effects of the steel superstructure. The short “frost free” season for weather sensitive work is less than 100 days. During this season, the grout installation, concrete infills and pavement required well laid out construction plans to ensure an efficient execution.
Although the Deh Cho Bridge project presented many logistical, weather and construction engineering challenges, the project was delivered with a first-in-class safety record, high quality, and within the expectations of the owner in terms of schedule. With 100 dedicated and skilled workers on the project, Ruskin has successfully built the first structure over the largest river in Canada.