Tibbitt to Contwoyto Winter Road, Northwest Territories and Nunavut
The Tibbitt to Contwoyto Winter Road is a heavy-haul ice road that provides the only land-based access to the resource rich area in the central part of the Canadian North. Tetra Tech has provided ice engineering and related services to support the road’s continued operation.
In operation since 1983, it extends more than 500 kilometers, traveling through boreal forest and across Arctic tundra to serve the needs of operating and developing mines in the Northwest Territories and Nunavut. More than 80 percent of the road is constructed on lake ice. Increased traffic volume and size of vehicles, combined with an uncertain season each year due to climate change, requires a risk management program that ensures operational decisions regarding allowable truck loads are based on sound engineering principles.
Tetra Tech’s ice engineering and geophysical team has provided integrated services, including:
- Analyzing ice-carrying capacity to calculate ice thickness for safely carrying heavy loads
- Collecting ice thickness and shallow bathymetry data using ground penetrating radar (GPR) to review the road’s conditions and identify potential problems
- Profiling through-ice bathymetry using GPR, which identifies shoals to anticipate problem areas for heavy traffic, and collecting water volume data to comply with water withdrawal regulations, which has provided the road operator significant logistical cost savings
- Measuring in situ ice strength to verify that built flood ice is comparable to natural lake ice
To enhance the effectiveness of these services, Tetra Tech introduced the following innovations:
- Modified standard GPR ice profilers using customized hardware and software for increased efficiency
- Developed a real-time ice profiling system to measure ice thickness and water bathymetry
- Developed a GIS database system containing all recent road field data to enable more effective planning
Tetra Tech has also conducted ecological land classification investigations as an integral part of a comprehensive investigation to assemble environmental and engineering baseline information for the winter road. This information was used to support the renewal of the license of occupation provided by the Canadian federal government.
The uncertainty of seasonal length due to climate change has prompted the development of overland options for part of the alignment. In 2008, Tetra Tech conducted environmental and engineering field programs, routing analysis and preliminary designs for a 160-kilometer seasonal overland route at the south end of the winter road.