Abstract:
The Siuslaw and Willamette National Forests in western Oregon have approximately 8,000 mi (12,900 km) of aggregate- and native-surfaced roads. These forest roads provide access for the general public (mainly recreation) and allow timber to be hauled to local lumber mills. The forests have developed a procedure for assessing whether an existing aggregate-surfaced road has the capacity to support this traffic. The procedure notes any existing surface distress, determines aggregate depths and material quality, ascertains the subgrade characteristics along the road segment, and then segments the road into like sections according to these observations. Next, the surfacing thickness program of the U.S. Department of Agriculture Forest Service is used to determine aggregate requirements for supporting traffic without excessive surface deterioration. Options for mitigating typical surface distress are addressed. The Siuslaw and Willamette National Forests have found that this procedure provides a reasonable and cost-effective means with which to determine where to apply aggregate on forest roads and how much, conserving the limited rock resources in national forest lands.
