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BLM>Idaho>Programs>Planning>Travel Management>Craters of the Moon >Road and Trail Classifications
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Shoshone Field Office

Craters of the Moon National Monument and Preserve Travel Management

Road and Trail Classifications

Within the Monument, a “road” is defined as an established route capable of accommodating travel by a full-sized automobile or truck. Following other routes or establishing new routes with motorized or mechanized vehicles is considered “offroad” use, which is prohibited in the Monument. Following are four different road classifications and two trail classifications within the Monument:

•  Class A Roads generally are paved and have a surface of asphalt, concrete, or similar continuous material. In addition to US Highway 20/26/93 (US 20/26/93), the only Class A roads are the loop drive, spur roads, and associated parking areas in the original NPS Monument. Class A roads are only found in the Frontcountry Zone. 

•  Class B Roads are improved roads constructed with a natural or aggregate surface, and they may have berms, ditches, or culverts. Regular maintenance allows passage by standard passenger and commercial vehicles such as cars, light trucks, and some heavy trucks. Seasonal conditions and lack of snow removal may render these roads impassable. Class B roads are found primarily in the Passage Zone. 

•  Class C Roads have a natural surface and may be either constructed or established over time by repeated passage of vehicles. The natural surface may be dirt, sand, or rock. A minimal amount of maintenance, if any at all, is limited primarily to spot surface grading to allow vehicle passage within the original road corridor. 

Maintenance on these roads is performed only as necessary, not in accordance with any regular schedule. Class C roads accommodate a much smaller range of vehicles than Class B roads, usually high-clearance two-wheel-drive and four-wheel drive vehicles. Seasonal conditions or wet weather may render these roads impassable at any time. Class C roads are found primarily in the Passage and Primitive Zones.

•  Class D Roads are primitive roads that were not constructed but have been established over time by the passage of motorized vehicles. These roads receive no maintenance or grading. However, management retains the authority to perform occasional emergency repairs or maintenance as necessary for administrative purposes and general resource protection. These roads are generally referred to as “two-tracks” or a set of two ruts with vegetation growing in between the wheel ruts. The condition of these roads varies from sometimes passable by a passenger car to only suitable for high-clearance fourwheel-drive vehicles. Seasonal conditions or wet weather may render these roads impassable at any time.
Class D roads are found primarily in the Primitive Zone. Class D Roads and other existing roads include only those roads in existence as of the date of Monument Proclamation 7373 and shown on Figure 4. Any routes created by crosscountry vehicle or mechanical use since the date of Proclamation 7373 are considered illegal and will be closed.

•   Class 1 Trails are restricted to nonmotorized/non-mechanized travel (wheelchairs are allowed). Examples of permitted forms of travel include foot travel, pack animal, and horseback. Examples of prohibited forms of travel on Class 1 trails include mountain bikes and all motorized vehicles. Class 1 trails may be further restricted, for example, to foot travel only.

•   Class 2 Trails are open to motorized/ mechanized travel in addition to foot travel, pack animal, horseback, and other forms of passage. Examples of prohibited forms of travel include any vehicle with a footprint wider than an 18-inch tread (all-terrain vehicles, four-wheelers, and four-wheel-drive vehicles). Class 2 Trails can only be created from decommissioned roads that will no longer be open to use by full-sized vehicles. No new Class 2 Trails will be created in any other manner.

The Proposed Craters of the Moon National Monument and Preserve (Monument) Management Plan/Final Environmental Impact Statement (July 2005) categorized routes and other travel features within the Monument as Class A, B, C, and D roads, as well as Class 1 and Class 2 trails. Since that time, The Bureau of Land Management (BLM) has adopted a new policy for defining these types of routes (
We are required to use the new system of describing Roads, Primitive Roads and Trails in the Travel Management Plan. Please see the definitions below.
Road: A linear route declared a road by the owner, managed for use by low-clearance vehicles having four or more wheels, and maintained for regular and continuous use.
Primitive Road: A linear route managed for use by four-wheel drive or high-clearance vehicles. These routes do not normally meet any BLM road design standards.
Trail: A linear route managed for human-powered, stock, or off-highway vehicle forms of transportation or for historical or heritage values. Trails are not generally managed for use by four-wheel drive or high-clearance vehicles.
What this means for the Craters Travel Plan:
All Class A and B roads within in the Monument will become “Roads” for travel planning purposes. All Class C and D roads will be described as “Primitive Roads.” Trails will still be described as “Trails” and the definitions for Class 1 and 2 trails remains the same as in the Monument Management Plan.

Road Class–Monument Management Plan
New Road Class
New Miles
Class A
Class B
Class C
Primitive Road
Class D
Class I Trail
Class II Trail
Total Miles