The passage of heavy vehicles (high per axle weight) during the spring thaw causes faster degradation of the pavement and leads to increased maintenance costs. To reduce the damage, most provinces in Canada implement spring load restrictions for heavy vehicles. Given that conditions often veer from climatology and that regional climatology is changing, imposing load restrictions at fixed dates every year is not optimal: it can lead to increased road damage and/or increased costs to the transportation industry. The main goal of this project was to develop an objective guidance to help departments of transportation determine the beginning and end of the seasonal load adjustment periods, long enough in advance for the road transportation industry to adjust their plans. A soil energy and mass balance model driven by atmospheric conditions from numerical weather prediction models to predict soil temperature and moisture content was selected since it offers a complete physical deterministic approach. With funding from the Nova Scotia Department of Transportation and Infrastructure Renewal, six probes capable of measuring both soil temperature and moisture to a depth of 150 cm were installed at various locations around Nova Scotia in 2010. Using data from these sensors, AMEC then initialized a point subsurface model to produce a five day prediction of subsurface temperatures. Results to date are promising and indicate that it is possible to provide advance warning of the spring thaw in roads. Research is ongoing to better incorporate moisture data, review other existing subsurface models, and investigate driving the models with different sources of forecast data.
