National Trail Surfaces Study

Definitions of Terms

For the purpose of this study and further discussion, the following terms will be used:

Aggregate. Crushed limestone (crushed shale or rock in regions that limestone is not available), natural soils, or dirt that is brought in from a different location than the actual site.

Firmness. The degree of surface resistance to deformation, especially by indentation or the movement of objects (U.S. Access Board, 2007).

Rotational Penetrometer. The instrument used in field-testing to test for compliance with the Outdoor Developed Areas Guidelines firmness and stability recommendations. The Rotational Penetrometer, developed by Beneficial Designs, uses a wheelchair caster placed on a spring loaded caliber in a metal tripod frame which suspends the caster about 6 inches over the surface. When the caster is released, the spring load gauge replicates the force of an individual in a wheelchair over a given surface. The penetration into the surface is measured for readings of “firmness.” The test for stability requires the caster of the Rotational Penetrometer to be moved from side to side to determine the horizontal displacement of the surface material.

Soil Stabilizer. A product that is applied either topically, or mixed-in that acts as a binding agent to either native soils or an additional type of aggregate. The soil stabilizers chosen for this study are all "green" products meaning that they come from natural by products.

Stability. The degree to which a surface resists change from contaminants or applied force, so that when the contaminant or force is removed, the surface returns to its original condition (U.S. Access Board, 2007).

Trail. A pedestrian route developed primarily for outdoor recreational purposes (U.S. Access Board, 2009).