One of the challenges of working in artic regions is the short time window within which ice road operations are viable. Being able to extend the spring operation of ice roads one to two weeks is of great benefit to our clients.
In order to extend ice road operability, the ice road surface and the structural integrity of the ice must be preserved. A similar set of procedures can be employed for most sites, but are applied at slightly different times depending on the geographic location (i.e. temperature variability) and ice type (sea ice versus fresh water ice).
In addition to these procedures, ice road temperature profiles (an indication of ice strength) and borehole jack strength measurements are key parameters to be monitored and compared to accepted safety standards. Site engineers must constantly monitor ice temperature and borehole strengths for extended spring season operation to apply load reductions as the season progresses.
In this discussion, we examine the following topics for prolonged operations of ice roads:
- Maintaining an insulating layer and a surface-reflective high albedo on the ice road surface
- Preserving the ice road snow banks and ice road width
- Sustaining ice road access ramps from lake or sea ice to shore.
Maintaining an Insulating Layer and High Albedo on the Ice Road.
Preserving cold ice temperatures and the travel surface of an ice road are critical for prolonged safe use of an ice road. Using snow as a natural insulator involves grading and blowing snow on the ice road as the spring season progresses. Snow windrows that accumulate along the ice road through the winter are often employed for this purpose. By maintaining an insulating layer with high albedo, the road surface reflects an increased amount of radiation, reducing the heat absorbed. Insulating rig or environmental mats can also be used as a shield.
Dirt and debris should be removed from the road on a daily basis to discourage the development of localized melting zones. Limiting the use of the ice road to night time will also preserve the road surface.
Ice Road Width & Snow Banks
The construction and maintenance of an ice road at a proper width is also an important consideration. The ice road should not be widened as the season progresses for safety concerns due to weakened and thinner ice under the snowbanks at the margin of the ice road.
High snow banks at the road edge should be avoided as they cause high stresses and consequently result in excessive deflection of the ice sheet. This becomes asafety issue especially with spring season operation where the deflection pushes the ice road surface below water level and flooding occurs.
Maintaining safe access ramps to the ice road from the shore is critical for continued operation. We recommend the following:
- Construction of ramps in a north to east facing direction to avoid late day direct sunlight
- A thick snow and ice layer should be placed on the ramps over the winter season to ensure that bare ground does not become exposed as the spring season progresses
- Rig or environmental mats should be placed on the ground surface under the snow layer at the critical shoreline point to ensure that this transition zone does not become exposed to sunlight in the case of excessive snow melt.
In conclusion, it is emphasized that site engineering on a case-by-case bases with monitoring of co nditions is key to a safe and successful extended spring season ice road operation. Performing engineering monitoring on site prior to any indication of melting or ice road deterioration is important for evaluating and understanding how weather patterns and forecasts will impact site condition as the spring season progresses.
We have successfully applied the aforementioned procedures to extend ice road operations for numerous ice road engineering projects in Northern Canada and Alaska for resource extraction projects.
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