An Overview of Major Engineering Challenges for Developing Transportation Infrastructure in Northern Canada

The transportation corridor proposed to support the development of northern Canada travels extensively through areas of permafrost. The main concern for sustainably developing infrastructure in permafrost terrain arises from melting the ground ice contained in the frozen soils, which can yield to ground subsidence and other geohazards. Permafrost degradation may be triggered by natural processes or anthropogenic activities; it is compounded with climate change, and its impacts on infrastructure are widespread in the Arctic. Advancing our understanding of permafrost dynamics is critical to minimize impacts from geohazards on infrastructure and detrimental consequences on the surrounding natural environment. Permafrost dynamics involve the interactions between factors from the climate,ground surface and subsurface, and in some instances with anthropogenic activities (e.g., infrastructure). Assemblage of these components forms a permafrost geosystem where interactions and feedback are key to the state of permafrost; this aligns with Aristotle’s concept that “the whole is greater than the sum of its parts.” To comprehend permafrost dynamics and interactions with infrastructure, we must characterize the system components and monitor changes. Using comprehensive and interdisciplinary approaches is important because critical linkages may fall at the intersection of disciplines. Infrastructure construction in the North is challenging in many ways. Construction and material sites are remote, harsh weather conditions are frequent and construction methods and infrastructure maintenance in permafrost-affected soils can be difficult and costly. The most common approach is to build and maintain. This strategy involves allowing permafrost degradation to occur and preserving serviceability by intensive maintenance. It generally results in a reduced level of service, comfort, safety and shorter life cycles. Stabilization techniques are required when loss or low level of service are not acceptable. In the context of climate change and widespread permafrost degradation, mitigation techniques are also becoming important for infrastructure that was previously developed according to the build-and-maintain strategy. The different mitigation methods used to limit permafrost degradation along infrastructure can be classified into four main categories: Limitation of ground heat intake in summer; Enhancement of heat extraction from the ground in winter; Reinforcement of the infrastructure embankment and ground stability improvement; and Water management to reduce thermal erosion. There is no generic solution to control permafrost degradation along infrastructure, and rather, the selection of mitigation methods is based on site-specific conditions and is part of the infrastructure management strategy. Maintaining adequate structural and functional conditions of infrastructure, which implies proper investments, is at the heart of solutions for sustainable northern development. All governments, designers, contractors and operators must recognize the need for proper infrastructure management and embrace the role it plays in ensuring the predictability and safety of our public infrastructure. Our understanding of permafrost science and engineering has largely progressed in the last decades, yet important knowledge gaps remain and these need to be addressed for sustainably developing infrastructure in northern Canada. The following were identified as important remaining challenges: intensify efforts to develop knowledge, expertise and reference documents using an interdisciplinary and collaborative approach; foster communication between stakeholders, scientists, engineers and planners and involve First Nations; develop new, affordable and effective technology for permafrost characterizations and monitoring; improve infrastructure design and develop new adaptation technologies; and develop management tools for infrastructure and risk management adapted to northern conditions.

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