The Problem Frost action in soils can cause damaging effects. One effect is the frost heave. Another is the loss of ability of the road base to support heavy traffic. Reduced base course strength occurs during thawing periods. Ice melts from the top down, trapping water until lower ice layers melt.
Trapped water saturates the wearing and base course layers.
This results in more moisture than the pavement was designed for and reduces the strength of the pavement and its supporting base. Any lowering of base material strength or increase in the number of loads reduces the life of the pavement. Therefore, reducing loads when the strength of the pavement materials is reduced is a reasonable way to maintain the design life and general serviceability of the pavement. In New Hampshire seasonal load limits are usually placed on roads carrying less than 5000 vehicles per day and subject to excessive damage during the thawing period. To select which pavements are candidates for load restrictions, agencies should consider surface thick-ness, the type of subgrade, and local experience relating to observed moisture and pavement distress.