Modeling risks of functional degradation in the road network of Russian northern cities due to predictable climatic changes

Abstract

Predictable climate warming naturally leads to excessive thawing of permafrost soils and damage to the road network built on them. Using methods of mathematical modeling, we quantitatively estimated the additional risk associated with an increase in the mean annual air temperature by up to 2°C for the largest Russian northern cities (Murmansk, Norilsk, and Yakutsk). The current climate condition that serves as the basis for the design of roads was determined with account for long-term data of instrumental observations. The depth of additional soil thawing in the road base and its settlement in changing climatic conditions were calculated in accordance with existing design standards. The basic risk level corresponding to the maximum permissible settlements was conventionally adopted as 100%. The settlement of the road pavement was calculated for two cases: for undamaged fragments of the road network and with account for the initial settlement in them. The second case reflects the road network condition in the cities under consideration more realistically. With regard to it, we got significantly higher estimates of the predicted risk — up to 307% at an increase in temperature by 2°C (while in the first case, they were up to 78%). The paper shows that saturated soils in the road base are associated with aggravated risk of settlements in the road pavement. As for clayey soils, the potential excess of the basic risk level was recorded at an increase in air temperature by 1°C, and for sandy soils — by 1.5°C. We show a clear relationship between the predicted risk level and climatic and soil features of the territory.