Vulnerability to Climate Change Assessment for a Highway Constructed on Permafrost

The 93 km section of Highway 3 located between Behchoko (Rae-Edzo) and Yellowknife is located in an area with warm and discontinuous permafrost and variable ground ice contents. The highway was originally constructed as a gravel road in 1968. Between 1999 and 2006, the alignment for this section of highway was straightened and reconstructed, and the road surface chip-sealed. To date, this section of highway has experienced significant sagging in soil-covered areas and requires considerable maintenance efforts to keep the road in a comfortable and safe driving condition. Embankment deformations have been attributed to the degradation of the ice-rich permafrost foundation. The Public Infrastructure Engineering Vulnerability Committee (PIEVC), a national committee established by Engineers Canada, has developed a standardized protocol to assess the vulnerability of Canada's public infrastructure to climate change. The protocol continues to be tested on a variety of public infrastructures and in 2010, this section of highway was evaluated as a case study. More than 1100 highway infrastructure element - climate event combinations were assessed. Out of these combinations, five were identified as high risk. The assessment identified those sections of the highway built on ice-rich permafrost as being at greatest risk, based on its low capacity to withstand the projected or anticipated climate-change related loads. Overall, the road embankment stability was found to be insensitive to climate change such that only functionality losses are expected, not sudden losses in capacity. Climate change will likely increase maintenance and repair efforts needed to maintain safe driving conditions.