Engineering Stable Roads on Permafrost: The Role of Geocells in Northern Canada
Permafrost presents significant challenges to engineers, contractors and town planners building and maintaining infrastructure in Northern Canada.
With global warming increasingly driving thaw of permafrost, road instability in areas like Yukon, Northwest Territories and Nunavut has become common.
The situation has necessitated that new solutions be found and implemented.
Geocell technology for northern road construction has proven to be one such mitigation measure, with Neoloy Tough-Cells solutions, supplied by PRS Geo Technologies, taking the fight to permafrost.
Why Roads Built on Permafrost Fail in Northern Canada
Permafrost refers to soil, rock or sediment that stays frozen for at least two consecutive years.
In Canada it underlies about half the total landmass, with most occurring in the country’s north where roads are especially vulnerable.
Thawing permafrost causes ice-rich soils to lose volume and leads to uneven ground and structural deformation.
Seasonal freeze–thaw cycles are particularly notorious for reducing the strength of granular road layers, particularly in instances where poor drainage accelerates thaw and erosion.
Repairing northern infrastructure that has been impacted by permafrost thaw is extremely costly once failure occurs.
Over a three-year period, permafrost-related damage to the Iqaluit airport landing strips and facilities required $300 million in repairs.
Engineering Objectives When Designing Roads on Thaw-Sensitive Ground
While Northern Canada’s permafrost thaw cannot always be prevented, the onus falls on infrastructure professionals to manage deformation and extend the service life of roads.
According to the Transportation Association of Canada, traditional planning, design, construction and maintenance practices do not always suit permafrost conditions.
Climate change is also adding uncertainty to performance prediction.
There are three specific objectives when designing roads in this region: reduce stress transferred to thaw-weakened soils; limit rutting and deformation under traffic loads; and control water and drainage to slow further degradation.
It is often the case that thermal measures used with structural solutions yield far better results than when used alone.
How Geocells Improve Road Performance on Permafrost
Geocells, which take the form of a three-dimensional honeycomb-like confinement system that stabilizes soil by filling interconnected cells with aggregate, sand or soil, are coming to prominence in Northern Canada for a variety of reasons.
Because the structure confines aggregate, lateral movement is reduced and loads can be distributed more evenly over weak subgrades.
When the subgrade softens, geocell solutions for thawing permafrost help the road structure retain its shape and load-bearing capacity.
The system is particularly effective for the region’s gravel and low-volume roads.
Why Are Neoloy® Tough-Cells the Right Solution for Permafrost Road Applications
Neoloy Tough-Cells represent the latest proven advancements in geocell technology, with many years of experience, and are particularly relevant within the geocell Canada context.
These rigid cells are made from a unique Novel Polymeric Alloy (NPA) and are specifically engineered for long-term structural reinforcement and performance under heavy freight and industrial traffic, with the strongest stabilization under heavy loads.
Neoloy is known for its lowest deformation behavior and its ability to maintain confinement in the most efficient way over extended service lives.
Neoloy Tough-Cells allow engineers to create a mechanically stabilised base layer capable of performing reliably on thaw-sensitive soils such as those found in the region.
They display significantly improved base stiffness even with subgrade strength varying seasonally.
Furthermore, due to their unique confinement mechanism and Neoloy-specific design methodologies, they reduce reliance on thick imported aggregate layers in remote regions, thereby reducing material requirements, transportation demands, and overall construction costs.
Practical Application of Geocells on Northern Canadian Roads
Installation of Neoloy Tough-Cells on various projects aligns with the Canadian government’s efforts to address permafrost thaw and the effects of climate change on the region’s transport infrastructure.
Neoloy Tough-Cells have been successfully used to reinforce remote community access roads, mining and industrial haul roads and seasonal supply routes identified during these programmes.
The structure of these roads typically includes prepared subgrade, a Neoloy Tough-Cells confinement layer, granular infill, and gravel or asphalt wearing course.
Along with implementation of the cells, road projects also often require effective drainage design due to icings impairing water emissions. In such cases sinkholes are not uncommon.
In these challenging conditions, Neoloy Tough-Cells help mitigate the risks associated with poor drainage, icings, and localized instability by maintaining confinement, distributing loads effectively, and preserving road performance over time.
Using Geocells to Build More Resilient Permafrost Roads
With climate change accelerating there is no reason to believe that permafrost thaw will decrease in the foreseeable future.
What is clear is that responses need to be more targeted. In terms of geocell soil stabilisation for cold regions, Neoloy Tough-Cells solutions, are ideal thanks to their ability to extend road life and reduce maintenance demands.