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NATURAL RESOURCES CONSERVATION SERVICE CONSERVATION PRACTICE STANDARD

ACCESS ROAD (Ft.)

CODE 560

DEFINITION Where general public use is anticipated, roads shall be designed to meet applicable A travel-way for equipment and vehicles federal, state and local criteria. constructed as part of a conservation plan. Location. Roads shall be located to serve the purpose intended, to facilitate the control PURPOSE and disposal of surface and subsurface To provide a fixed route for vehicular travel water, to control or reduce erosion, to make for resource activities involving the the best use of topographic features, and to management of timber, livestock, agriculture, include scenic vistas where possible. The wildlife habitat, and other conservation roads should generally follow natural enterprises while protecting the soil, water, contours and slopes to minimize disturbance air, fish, wildlife, and other adjacent natural of drainage patterns. Roads shall be located resources. where they can be maintained and where water management problems are not created. To reduce potential pollution, roads CONDITIONS WHERE PRACTICE APPLIES shall be located away from water bodies and Where access is needed from a private or watercourses. Overland flow should not be public road or highway to a land use impeded. Utilize buffers where possible to enterprise or conservation measure, or where protect waterbodies. travel ways are needed in a planned land use Alignment. The gradient and horizontal area. alignment shall be adapted to the intensity of Access roads range from seasonal use use, mode of travel, the type of equipment roads, designed for low speed and rough and load weights, and the level of driving conditions, to all-weather roads development. heavily used by the public and designed with Grades normally should not exceed 10 safety as a high priority. Some roads are percent except for short lengths. Maximum only constructed for a single purpose; i.e. grades of 18 percent should only be control of forest fires, logging and forest exceeded if necessary for special uses such management activities, access to remote as logging roads, field access roads, fire recreation areas, or access for maintenance of facilities. protection roads or other roads not accessible for use by the general public.

CRITERIA For stream crossings, the road should be aligned so that it crosses perpendicular to the Access roads shall be designed to serve the channel as much as possible. enterprise or planned use with the expected vehicular or equipment traffic. The type of Width. The minimum width of the roadbed is vehicle or equipment, speed, loads, soil, 14 ft for one-way traffic and 20 ft for two-way climatic, and other conditions under which traffic. The roadbed width includes a tread- vehicles and equipment are expected to width of 10 feet for one-way traffic or 16 feet operate need to be considered. for two-way traffic. Each type of road also

Conservation practice standards are reviewed periodically, and updated if needed. To obtain NRCS, NHCP the current version of this standard, contact your Natural Resources Conservation Service State Office, or visit the Field Office Technical Guide. July 2010 560 - 2 requires 2 feet of shoulder width on each An erosion-resistant low point or overflow side. Single-lane logging or special-purpose area may be constructed across the access roads can have a minimum width of 10 feet, road to supplement culvert capacity on non- with greater widths at curves and turnouts. public use roads. Culverts, bridges, fords The two-way traffic width shall be increased and hardened overflow areas should be approximately 4 feet for trailer traffic. The installed so the road crossing does not shoulder width may be either gravel or grass. significantly impact fish migration. Turnouts shall be used on single lane roads Roadside ditches shall be adequate to where vehicles travel in both directions on a provide surface drainage for the roadway and limited basis. Where turnouts are used, road deep enough, as needed to serve as outlets width shall be increased to a minimum of 20 for subsurface drainage. At a minimum, the feet for a distance of at least 30 feet. roadside ditch shall be 1.0 foot below the top Side Slopes. All cuts and fills shall be of road surface to provide internal drainage. designed to have stable slopes of a minimum Ditch channels shall be designed to be on of 2 horizontal to 1 vertical on heights of less stable grades or protected with structures or than 4 feet. For short lengths, rock areas, or linings for stability. very steep hillsides, steeper slopes may be permitted, if soil conditions warrant and Water-breaks, water-bars, diversions or special stabilization measures are installed. broad based dips may be used to control surface runoff on low-intensity use forest, Areas with geological conditions and soils ranch or similar roads. On steep grades subject to slides shall be avoided or treated where runoff and erosion is anticipated down to prevent slides. the road, water bars should be considered. Drainage. The type of drainage structure Water bars must be constructed of materials used will depend on the intended use and that are compatible with the use and runoff conditions. Culverts, bridges, fords, or maintenance of the road surface. Water bar grade dips for water management shall be discharge areas must be well vegetated or provided at all natural drainage ways. The have other erosion resistant materials. See capacity and design shall be consistent with Figure 1 Recommended Spacing of Relief sound engineering principles and shall be Culverts and Water Bars Based on Soil Type. adequate for the class of vehicle, type of Surface crowning can also help direct road road, development, or use. When a culvert runoff into the side drainage ditches. or bridge is installed in a drainage way, its Unobstructed flow into the ditches must be minimum capacity shall convey the design maintained to prevent flows from causing storm runoff without causing erosion or road roadside erosion. Provide a turnaround at overtopping. Table 1 lists minimum design the end of dead end roads. In some areas, storm frequencies for various road types. turnarounds may also be desirable for Table 1 stream, lake, recreation, or other access purposes. Storm Road Type Frequency Provide parking space as needed to keep Forest Access Roads, vehicles off the road or from being parked in 2 year - 24 Farm Field Access undesirable locations. Hour Roads Surfacing. Access roads shall be given a Farm Driveways, wearing course or surface treatment if Recreation Facility 10 year - 24 required by traffic needs, soil, climate, Access Roads Hour erosion control, or particulate matter emission control. The type of treatment, if needed, depends on local conditions, Public Access Roads, 25 year - 24 available materials, and the existing road Camp grounds, etc. Hour base. If these factors or the volume of traffic is not a problem, no special treatment of the surface is required. On weak bearing capacity soils such as silts, organics, and

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clays, the surface treatment should be Construction Operations. Construction underlain with a geotextile material operations should be carried out in such a specifically designed for road stabilization applications when the road is used on a manner that erosion and air and water regular basis. pollution are minimized and held within legal limits. Construction shall include the Unsurfaced roads may require controlled following requirements as necessary for the access to prevent damage or hazardous job: conditions during adverse climatic conditions. 1. Trees, stumps, roots, brush, weeds, and Toxic and acid-forming materials shall not be other objectionable material shall be used on roads. This should not be construed removed from the work area. to prohibit use of chemicals for dust control 2. Unsuitable material shall be removed and snow and ice removal after considering from the roadbed area. potential impacts on stabilizing vegetation. 3. Grading, sub-grade preparation, and compaction shall be done as needed. Utilize additional conservation practices to 4. Surfacing shall be done as needed. reduce the potential for generation and transport of particulate matter emissions. 5. Measures must be in place to limit the generation of particulate matter during construction. Figure 1. Recommend Spacing of Relief Culverts and Water Bars Based on Soil Types

450 400 350 Gravely Soils 300

250 200 150

( feet) Spacing 100 Sands, Silts & Clay Soils 50 0 0 2 4 6 8 10 12 14 16 18 20

Road Grade (%)

Traffic Safety. Passing lanes, turnouts, entered either at the top of a hill or far guardrails, signs, and other facilities as enough from the top or a curve to provide needed for safe traffic flow shall be visibility and a safe sight distance. The provided. Traffic safety shall be a prime clear sight distance to each side shall not factor in selecting the angle and grade of be less than 300 feet or as required by local the intersection with public highways. regulations. Preferably, the angles shall be not less than Erosion Control. If soil and climatic 85 degrees. The public highway shall be conditions are favorable, roadbanks and NRCS, NHCP July 2010 560 - 4

disturbed areas shall be vegetated as soon soluble and sediment-attached as possible and skid trails, landings, substances that would be carried by logging, and similar roads shall be runoff from construction activities. vegetated after harvesting or seasonal use • is completed (see Critical Area Planting- Effects on wetlands and water-related 342). If the use of vegetation is precluded wildlife habitats that would be and protection against erosion is needed, associated with the practice. protection shall be provided by non- • Establishing vegetation on road vegetative materials, such as gravel or shoulders wider than the 2-4 ft. other organic or inorganic material (see Mulching 484), or in accordance with local • Limiting the number of vehicles and regulations. vehicle speed will reduce the potential for generation of particulate matter and Roadside channels, cross drains, and decrease safety and air quality drainage structure inlets and outlets shall concerns. be designed to be stable (see Structure for Water Control). If protection is needed, riprap or other similar materials shall be PLANS AND SPECIFICATIONS used. Plans and specifications for constructing Watercourses and water quality shall be access roads shall be in keeping with this protected during and after construction by standard and shall describe the erosion-control facilities and maintenance. requirements for applying the practice to Filter strips, water and sediment control achieve its intended purpose. basins, and other conservation practices shall be used and maintained as needed. OPERATION AND MAINTENANCE An operation and maintenance plan will be CONSIDERATIONS developed and carried out for the life of the Consider visual resources and practice: environmental values during the planning 1. Inspect culverts, roadside ditches, and designing of the road system. water bars and outlets after each major When available, consider using organic bio- runoff event and restore flow capacity degradable materials as a surface as needed. treatment. 2. Minimize the damage to vegetative Access roads should be located where buffers adjacent to the road when it is minimal adverse impacts will affect necessary to chemically treat the road wetlands, water bodies, watercourses, surface to maintain erosion protection. wildlife habitat, and air quality. 3. Maintain vegetated areas in adequate Consideration should be given to the cover to meet the intended purpose(s). following: 4. Fill low areas in travel treads and re- • Effects on downstream flows or grade, as needed, to maintain road aquifers that would affect other water cross section. uses or users. 5. Inspect roads with water-bars • Effects on the volume and timing of periodically to insure proper cross downstream flow to prohibit undesirable section is available and outlets are environmental, social, or economic stable. effects. 6. Conservation practices that limit • Short-term and construction-related particulate matter emissions should be effects of this practice on the quality of incorporated into long-term on-site downstream water courses. maintenance plans. • Overall effects on erosion and the movement of sediment, pathogens, and

NRCS, NHCP July 2010