Estimating When to Apply and Remove Spring Load Restrictions

A significant percentage of roads in seasonal frost areas are not designed to carry normal loads during the spring thawing process. Determining dates to apply and remove seasonal load restrictions (SLR) is of great interest to many federal, state and local agencies. In a recent study for the USDA Forest Service, Berg (2004) developed a method which estimated SLR application dates at a site in Minnesota and another in Ohio. In this report, we apply the same method to estimate SLR application dates on a road in New Hampshire and an airport parking apron in Vermont. The calculated results are compared to dates the SLR was actually applied and computed results were nearly the same as the application dates which were established by state DOT personnel. The method is also extended to estimate the time that the SLR can be removed. The Modified Berggren Equation was used to develop a procedure, but a regression equation developed by Rutherford, Mahoney, Hicks and Rwebingira (1985) was more accurate when compared to measured data.