Access Road Conservation

8/2/2019 Access Road Conservation

1/4

560 - 1

NRCS, NHCP

July 2010

Conservation practice standards are reviewed periodically, and updated if needed. To obtainthe current version of this standard, contact your Natural Resources Conservation ServiceState Office, or visit theField Office Technical Guide.

NATURAL RESOURCES CONSERVATION SERVICE

CONSERVATION PRACTICE STANDARD

ACCESS ROAD

(Ft.)

CODE 560

DEFINITION

A travel-way for equipment and vehiclesconstructed as part of a conservation plan.

PURPOSE

To provide a fixed route for vehicular travelfor resource activities involving themanagement of timber, livestock, agriculture,wildlife habitat, and other conservationenterprises while protecting the soil, water,air, fish, wildlife, and other adjacent naturalresources.

CONDITIONS WHERE PRACTICE APPLIES

Where access is needed from a private orpublic road or highway to a land useenterprise or conservation measure, or wheretravel ways are needed in a planned land use

area.

Access roads range from seasonal useroads, designed for low speed and roughdriving conditions, to all-weather roadsheavily used by the public and designed withsafety as a high priority. Some roads areonly constructed for a single purpose; i.e.control of forest fires, logging and forestmanagement activities, access to remoterecreation areas, or access for maintenanceof facilities.

CRITERIAAccess roads shall be designed to serve theenterprise or planned use with the expectedvehicular or equipment traffic. The type ofvehicle or equipment, speed, loads, soil,climatic, and other conditions under whichvehicles and equipment are expected tooperate need to be considered.

Where general public use is anticipated,roads shall be designed to meet applicablefederal, state and local criteria.

Location. Roads shall be located to servethe purpose intended, to facilitate the controland disposal of surface and subsurfacewater, to control or reduce erosion, to make

the best use of topographic features, and toinclude scenic vistas where possible. Theroads should generally follow naturalcontours and slopes to minimize disturbanceof drainage patterns. Roads shall be locatedwhere they can be maintained and wherewater management problems are notcreated. To reduce potential pollution, roadsshall be located away from water bodies andwatercourses. Overland flow should not beimpeded. Utilize buffers where possible toprotect waterbodies.

Alignment. The gradient and horizontalalignment shall be adapted to the intensity ofuse, mode of travel, the type of equipmentand load weights, and the level ofdevelopment.

Grades normally should not exceed 10

percent except for short lengths. Maximumgrades of 18 percent should only beexceeded if necessary for special uses such

as logging roads, field access roads, fireprotection roads or other roads not

accessible for use by the general public.

For stream crossings, the road should be

aligned so that it crosses perpendicular to thechannel as much as possible.

Width. The minimum width of the roadbed is14 ft for one-way traffic and 20 ft for two-waytraffic. The roadbed width includes a tread-width of 10 feet for one-way traffic or 16 feetfor two-way traffic. Each type of road also
http://www.nrcs.usda.gov/about/organization/regions.htmlhttp://www.nrcs.usda.gov/about/organization/regions.htmlhttp://www.nrcs.usda.gov/technical/efotg/http://www.nrcs.usda.gov/technical/efotg/http://www.nrcs.usda.gov/technical/efotg/http://www.nrcs.usda.gov/technical/efotg/http://www.nrcs.usda.gov/about/organization/regions.html


2/4

560 - 2

NRCS, NHCP

July 2010

requires 2 feet of shoulder width on eachside. Single-lane logging or special-purposeroads can have a minimum width of 10 feet,with greater widths at curves and turnouts.The two-way traffic width shall be increasedapproximately 4 feet for trailer traffic. Theshoulder width may be either gravel or grass.

Turnouts shall be used on single lane roads

where vehicles travel in both directions on alimited basis. Where turnouts are used, road

width shall be increased to a minimum of 20feet for a distance of at least 30 feet.

Side Slopes. All cuts and fills shall bedesigned to have stable slopes of a minimumof 2 horizontal to 1 vertical on heights of lessthan 4 feet. For short lengths, rock areas, orvery steep hillsides, steeper slopes may bepermitted, if soil conditions warrant andspecial stabilization measures are installed.

Areas with geological conditions and soilssubject to slides shall be avoided or treated

to prevent slides.

Drainage. The type of drainage structureused will depend on the intended use andrunoff conditions. Culverts, bridges, fords, orgrade dips for water management shall beprovided at all natural drainage ways. Thecapacity and design shall be consistent withsound engineering principles and shall beadequate for the class of vehicle, type ofroad, development, or use. When a culvert

or bridge is installed in a drainage way, itsminimum capacity shall convey the designstorm runoff without causing erosion or roadovertopping. Table 1 lists minimum designstorm frequencies for various road types.

Table 1

Road TypeStorm

FrequencyForest Access Roads,Farm Field AccessRoads

2 year - 24Hour

Farm Driveways,

Recreation FacilityAccess Roads

10 year - 24Hour

Public Access Roads,Camp grounds, etc.

25 year - 24Hour

An erosion-resistant low point or overflowarea may be constructed across the access

road to supplement culvert capacity on non-public use roads. Culverts, bridges, fords

and hardened overflow areas should beinstalled so the road crossing does not

significantly impact fish migration.

Roadside ditches shall be adequate to

provide surface drainage for the roadway anddeep enough, as needed to serve as outlets

for subsurface drainage. At a minimum, theroadside ditch shall be 1.0 foot below the top

of road surface to provide internal drainage.Ditch channels shall be designed to be onstable grades or protected with structures or

linings for stability.

Water-breaks, water-bars, diversions orbroad based dips may be used to controlsurface runoff on low-intensity use forest,

ranch or similar roads. On steep gradeswhere runoff and erosion is anticipated down

the road, water bars should be considered.Water bars must be constructed of materials

that are compatible with the use andmaintenance of the road surface. Water bar

discharge areas must be well vegetated orhave other erosion resistant materials. SeeFigure 1 Recommended Spacing of Relief

Culverts and Water Bars Based on Soil Type.

Surface crowning can also help direct roadrunoff into the side drainage ditches.

Unobstructed flow into the ditches must bemaintained to prevent flows from causingroadside erosion. Provide a turnaround atthe end of dead end roads. In some areas,turnarounds may also be desirable forstream, lake, recreation, or other accesspurposes.

Provide parking space as needed to keepvehicles off the road or from being parked inundesirable locations.

Surfacing. Access roads shall be given awearing course or surface treatment if

required by traffic needs, soil, climate,erosion control, or particulate matteremission control. The type of treatment, ifneeded, depends on local conditions,available materials, and the existing roadbase. If these factors or the volume of trafficis not a problem, no special treatment of thesurface is required. On weak bearingcapacity soils such as silts, organics, and


3/4

560 - 3

NRCS, NHCP

July 2010

clays, the surface treatment should beunderlain with a geotextile materialspecifically designed for road stabilizationapplications when the road is used on aregular basis.

Unsurfaced roads may require controlledaccess to prevent damage or hazardousconditions during adverse climatic conditions.

Toxic and acid-forming materials shall not beused on roads. This should not be construed

to prohibit use of chemicals for dust controland snow and ice removal after considering

potential impacts on stabilizing vegetation.

Utilize additional conservation practices toreduce the potential for generation and

transport of particulate matter emissions.

Construction Operations. Constructionoperations should be carried out in such a

manner that erosion and air and waterpollution are minimized and held within legallimits. Construction shall include thefollowing requirements as necessary for the

job:

1. Trees, stumps, roots, brush, weeds, andother objectionable material shall beremoved from the work area.

2. Unsuitable material shall be removedfrom the roadbed area.

3. Grading, sub-grade preparation, andcompaction shall be done as needed.

4. Surfacing shall be done as needed.

5. Measures must be in place to limit thegeneration of particulate matter during

construction.Figure 1. Recommend Spacing of Relief Culverts and Water Bars Based on Soil Types

450

400

350

300

250

200

150

100

50

0

0 2 4 6 8 10 12 14 16 18 20

Road Grade (%)

Traffic Safety. Passing lanes, turnouts,guardrails, signs, and other facilities asneeded for safe traffic flow shall beprovided. Traffic safety shall be a primefactor in selecting the angle and grade ofthe intersection with public highways.Preferably, the angles shall be not less than85 degrees. The public highway shall be

entered either at the top of a hill or farenough from the top or a curve to providevisibility and a safe sight distance. Theclear sight distance to each side shall notbe less than 300 feet or as required by localregulations.

Erosion Control. If soil and climaticconditions are favorable, roadbanks and

Spac

ing

(feet)

Gravely Soils

Sands, Silts & Clay Soils


4/4

560 - 4

NRCS, NHCP

July 2010

disturbed areas shall be vegetated as soonas possible and skid trails, landings,logging, and similar roads shall bevegetated after harvesting or seasonal useis completed (see Critical Area Planting-342). If the use of vegetation is precludedand protection against erosion is needed,

protection shall be provided by non-vegetative materials, such as gravel orother organic or inorganic material (seeMulching 484), or in accordance with localregulations.

Roadside channels, cross drains, anddrainage structure inlets and outlets shallbe designed to be stable (see Structure forWater Control). If protection is needed,riprap or other similar materials shall beused.

Watercourses and water quality shall beprotected during and after construction byerosion-control facilities and maintenance.Filter strips, water and sediment controlbasins, and other conservation practicesshall be used and maintained as needed.

CONSIDERATIONS

Consider visual resources andenvironmental values during the planningand designing of the road system.

When available, consider using organic bio-degradable materials as a surface

treatment.Access roads should be located whereminimal adverse impacts will affectwetlands, water bodies, watercourses,wildlife habitat, and air quality.Consideration should be given to thefollowing:

Effects on downstream flows oraquifers that would affect other wateruses or users.

Effects on the volume and timing ofdownstream flow to prohibit undesirable

environmental, social, or economiceffects.

Short-term and construction-relatedeffects of this practice on the quality ofon-site downstream water courses.

Overall effects on erosion and themovement of sediment, pathogens, and

soluble and sediment-attachedsubstances that would be carried byrunoff from construction activities.

Effects on wetlands and water-relatedwildlife habitats that would beassociated with the practice.

Establishing vegetation on roadshoulders wider than the 2-4 ft.

Limiting the number of vehicles andvehicle speed will reduce the potentialfor generation of particulate matter anddecrease safety and air qualityconcerns.

PLANS AND SPECIFICATIONS

Plans and specifications for constructingaccess roads shall be in keeping with thisstandard and shall describe therequirements for applying the practice toachieve its intended purpose.

OPERATION AND MAINTENANCE

An operation and maintenance plan will bedeveloped and carried out for the life of thepractice:

1. Inspect culverts, roadside ditches,water bars and outlets after each majorrunoff event and restore flow capacityas needed.

2. Minimize the damage to vegetativebuffers adjacent to the road when it isnecessary to chemically treat the roadsurface to maintain erosion protection.

3. Maintain vegetated areas in adequatecover to meet the intended purpose(s).

4. Fill low areas in travel treads and re-grade, as needed, to maintain roadcross section.

5. Inspect roads with water-barsperiodically to insure proper crosssection is available and outlets are

stable.

6. Conservation practices that limitparticulate matter emissions should beincorporated into long-termmaintenance plans.

Documents

Access Road Conservation