Freezing and thawing of sub-surface soils is a common occurrence in cold regions, and this process results in hundreds of millions of dollars of damage to roadways in the United States every year. When the soils freeze, they do so from the surface down, while in the spring, as temperatures warm on the surface, these same soils below the surface warm from the surface down. As springtime thawing takes place, road surfaces are susceptible to damage caused by vehicles carrying heavy loads over weakened roadbeds due to water trapped in the soils between the road surface and the frozen sub-surface. State departments of transportation attempt to mitigate this problem by placing load restrictions on selected roads prone to road surface damage due to sub-surface freezing. The major issue with placing load restrictions is knowing the right time to put them into place such that impact to commercial traffic is minimized while preserving the structural integrity of the roadway.

This paper presents a method being investigated by the University of North Dakota for the North Dakota Department of Transportation to improve the placing of load restrictions using an atmospherically-driven load restriction model. This paper will present the methodology of the model, as well as the efforts to instrument highways across North Dakota with sub-surface probes which measure conditions up to 2-meters beneath the road surface to support model initialization and verification.