Abstract
An integrated aggregate design and management system for forest roads in wet, mountainous terrain requires special considerations. Typically, subgrade soils, drainage conditions, and compactive effort vary along the length of new and existing roads. There are fewer testing opportunities for obtaining design parameters in these remote areas. Nevertheless, relatively small depths of aggregate can provide high performance. This design requires characterization of subgrade materials before or during construction. It uses steep road grades to advantage for effective drainage of the subgrade and aggregate. The design is used in conjunction with drainage practices that minimize erosion from reaching streams. Compaction effectiveness can be limited by soil moisture that is wet of optimum for compaction during the short construction period, requiring that aggregate depths be adjusted accordingly. To be used by practitioners, the design must be simple and not very conservative. Aggregate properties vary widely, and gradation specifications must be adjusted on the basis of these properties. Aggregate roads require timely inspection and should be graded only when they are rutted or major defects are present. Drainage and subgrade problems also need to be addressed during maintenance of the surface.
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