36 C.F.R. § 212.55 : Parks, Forests, and Public Property — FOREST SERVICE, DEPARTMENT OF AGRICULTURE — TRAVEL MANAGEMENT — DESIGNATION OF ROADS, TRAILS, AND AREAS FOR MOTOR VEHICLE USE — Criteria for designation of roads, trails, and areas

(a) General criteria for designation of National Forest System roads, National Forest System trails, and areas on National Forest System lands. In designating National Forest System roads, National Forest System trails, and areas on National Forest System lands for motor vehicle use, the responsible official shall consider effects on National Forest System natural and cultural resources, public safety, provision of recreational opportunities, access needs, conflicts among uses of National Forest System lands, the need for maintenance and administration of roads, trails, and areas that would arise if the uses under consideration are designated; and the availability of resources for that maintenance and administration.
(b) Specific criteria for designation of trails and areas. In addition to the criteria in paragraph (a) of this section, in designating National Forest System trails and areas on National Forest System lands, the responsible official shall consider effects on the following, with the objective of minimizing:
(1) Damage to soil, watershed, vegetation, and other forest resources;
(2) Harassment of wildlife and significant disruption of wildlife habitats;
(3) Conflicts between motor vehicle use and existing or proposed recreational uses of National Forest System lands or neighboring Federal lands; and
(4) Conflicts among different classes of motor vehicle uses of National Forest System lands or neighboring Federal lands.

In addition, the responsible official shall consider:

(5) Compatibility of motor vehicle use with existing conditions in populated areas, taking into account sound, emissions, and other factors.
(c) Specific criteria for designation of roads. In addition to the criteria in paragraph (a) of this section, in designating National Forest System roads, the responsible official shall consider:
(1) Speed, volume, composition, and distribution of traffic on roads; and
(2) Compatibility of vehicle class with road geometry and road surfacing.
(d) Rights of access. In making designations pursuant to this subpart, the responsible official shall recognize:
(1) Valid existing rights; and
(2) The rights of use of National Forest System roads and National Forest System trails under §212.6(b).
(e) Wilderness areas and primitive areas. National Forest System roads, National Forest System trails, and areas on National Forest System lands in wilderness areas or primitive areas shall not be designated for motor vehicle use pursuant to this section, unless, in the case of wilderness areas, motor vehicle use is authorized by the applicable enabling legislation for those areas.

36 C.F.R. § 212.55