Planning for the Inuvik to Tuktoyaktuk Highway required years of research, study and analysis. Each section of the road had to be studied for its unique features, both above and below the surface. The Department of Transportation commissioned several studies, including:
- Watercourse Tracking and Crossing Recommendations Table (Jan 2012) (goes over and assesses each water crossing and recommends to build culvert/bridge etc, assess fish habitat)
- Inuvik to Tuktoyaktuk Highway - Baseline Data Acquisition Program Terrain Evaluation (aerial evaluation)
- Terrain Analysis – Pingo study map
- Inuvik Airport Geophysics Investigation: Final Report (permafrost)
- Inuvik – Tuktoyaktuk Highway 2013-2014 Geotechnical Investigations Program
- Surficial Geology and Terriain Constraints – Inuvik to Tuktoyaktuk Highway
The ITH project area spans two distinct ecoregions: the Mackenzie Delta and the Tuktoyaktuk Coastal Plain. The Mackenzie Delta Ecoregion is part of the Taiga Plain Ecozone and consists of the southern two-thirds portion of the Mackenzie River Delta. Terrain in this area is characterized by a complex network of small lakes and interconnected channels. North and east of the Mackenzie Delta is the Tuktoyaktuk Coastal Plain. This ecozone includes the active portion of the Mackenzie River delta as well as uplands areas.
More specifically, the terrain along the ITH project area consist of rolling to gently undulating landscape characterized by glacial and post glacial deposits. These materials are deposited by streams and gravity related processes and are found along water courses and moderate to steep slopes. Very poorly-drained peat-covered areas are very common throughout the terrain, particularly in low-lying areas and nearby small bodies of water.
Detailed terrain and surficial material characterization and mapping in the project area was undertaken by KAVIK-STANTEC in 2012.The region is underlain by continuous permafrost with sediments often containing excess ice in the form of ice veins, lenses, wedges, and massive ice (Rampton 1988). Permafrost creates distinctive landforms throughout the area, such as polygonal networks and the area’s famous pingos. The active layer (the portion that thaws seasonally) varies in depth greatly, depending on the type of terrain and conditions such as water drainage, terrain details, etc. Work from Tarnocai et al. (2004) in the Inuvik –Tuktoyaktuk area indicates that active layer range anywhere from 30 cm to over 150 cm.
One of the most unique and special features of the northern Northwest Territories is its permafrost. Not altering or damaging the permafrost was one of the project partners’ primary concerns in developing the plan for the Inuvik to Tuktoyaktuk Highway.
Normally, road building requires a technique called “cut and fill.” These traditional construction methods cut into protective layers of surface vegetation and organics, with the possible results of a thawing in the permafrost below. To protect the permafrost along the proposed Highway alignment, “cut and fill” techniques will not be used for this project.
To protect the permafrost our design will use only fills – the ground will not be cut into. Instead, to reinforce the road, geotextile fabric will be placed between the existing ground and the construction materials along the entire highway. Geotextiles are special, permeable fabrics that are used to reinforce and strengthen roads.