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Accessibility Guidebook for Outdoor Recreation and Trails

Applying the Forest Service Trails Accessibility Guidelines (Continued)

Technical Provisions—How To Make a Hiker/Pedestrian Trail Accessible

Surfaces of Trails

Trail surfaces must be firm and stable. An exception to this requirement is allowed if a condition for departure exists.

Paving with concrete or asphalt is appropriate for highly developed areas. For less developed settings, crushed gravel, fine crusher rejects, packed soil, and other natural materials may provide a firm and stable surface. Natural materials also can be combined with synthetic bonding materials that provide stability and firmness. These materials may not be suitable for every trail, which is why the exception is permitted.

Slip resistance is not required for trails because tree and shrub leaves and needles, dirt, ice, snow, and other surface debris and weather conditions are part of the natural environment that would be difficult, if not impossible, to avoid.

The FSTAG defines a firm surface as a trail surface that is not noticeably distorted or compressed by the passage of a device that simulates a person who uses a wheelchair, as explained in the DESIGN TIP—What is Firm and Stable? Natural soils should be evaluated during the planning process for their ability to be compacted to a firm and stable surface under normally occurring weather conditions during the primary seasons of use. The FSTAG defines a stable surface as a trail surface that is not permanently affected by normally occurring weather conditions and that is able to sustain wear and tear produced by normal use between planned maintenance cycles. The determination of firmness and stability needs to be made keeping in mind the typical conditions that occur in the vicinity of the trail being evaluated. Local trail managers know the surface and how it wears throughout the primary seasons for which the trail is managed.

Clear Tread Width of Trails

Clear tread width means the width of the traveled surface on the ground and also above the ground between obstacles (figure 115). The clear tread of an accessible trail must be at least 36 inches (915 millimeters) wide. An exception permits the width to be reduced to 32 inches (815 millimeters) minimum if a condition for departure exists. A second exception allows an exemption from the clear tread provision if a condition for departure exists and the 32-inch (815-millimeter) width can't be achieved.

Illustration of two people hiking on a trail that passes between a steep hillside and a large tree. Dimensions show the required 36-inch (915-millimeter) clear tread width.
Figure 115—The requirements for clear
tread width on a trail.

Passing Spaces on Trails

A 60-inch (1,525-millimeter) clear tread width is required for two wheelchairs to pass comfortably and safely on a trail. However, this width is not always appropriate in all settings and for all trail classes. Where the clear tread width of a trail is less than 60 inches (815 millimeters), passing spaces are required at least every 1,000 feet (305 meters). An exemption is allowed if a passing space can't be provided because of a condition for departure.

Passing spaces must be at least 60 inches (1,525 millimeters) wide (including the trail width) by 60 inches (1,525 millimeters) long (figure 116). A T-intersection of two trails or other walking surfaces also can be used as a passing space, provided that the arms and stem of the T-shaped space extend at least 48 inches (1,220 millimeters) beyond the intersection (figure 117). Either configuration would provide enough room for someone to move to the side and let an oncoming person pass along the trail. The cross slope of a passing space should not exceed 1:20 (5 percent).

Illustration of a man using a wheelchair watching a dog while he sits in a wide section of a trail. Another man with a day pack is walking past. Dimensions show size and slope requirements for the passing space explained in the paragraph above.
Figure 116—The requirements for passing spaces.

Illustration of a "T"-intersection of two trails. A man with a service dog is approaching the intersection from one side. A man and woman are approaching from another side. Dimensions show size and slope requirements for the trail intersection to serve as a passing space, as explained in the paragraph above.
Figure 117—The requirements for passing
spaces at "T" intersections.

Tread Obstacles on Trails

A tread obstacle is anything that interrupts the evenness of the tread surface. On trails, tread obstacles often occur as a result of ruts, roots, and rocks in the tread surface. Tread obstacles generally can't be more than 2 inches (50 millimeters) high. Tread obstacles can be up to 3 inches (75 millimeters) high if the trail grade and cross slope are both 1:20 (5 percent) or less. These requirements minimize the chance that someone who uses a wheelchair might tip over when crossing a tread obstacle. An exemption from the obstacle height requirements is allowed if compliance isn't possible because of a condition for departure.

Protruding Objects and Trails

Protruding objects extend into the clear width area of a trail from beside or above the trail. Leaning tree trunks, rock ledges, and branches are common protruding objects. There must be at least 80 inches (2,030 millimeters) of clear headroom above trails, the same requirement as ABAAS section 307. If the vertical clearance of a trail is reduced to less than 80 inches (2,030 millimeters) because of a condition for departure, a barrier must be provided to warn people who are blind or visually impaired (figure 118). An exemption to the requirement is allowed where a condition for departure prevents installing a barrier or providing 80 inches (2,030 millimeters) of clearance. This exception allows a trail to pass under ledges or through caves without changing the character of undeveloped areas (figure 119).

Illustration of a man using a cane to search for the edge of a trail. He is shown encountering rocks that have been situated as a barrier warning of vertical clearance less than 80 inches (2,030 millimeters).
Figure 118—A warning barrier is required wherever
vertical clearance is insufficient.

Photo of a woman with sunglasses and a cane in a slot canyon, using her free hand to search the top of the entrance to a cave in the side of the bedrock canyon wall.
Figure 119—Entering a cave in an undeveloped area
managed by the Bureau of Land Management.

Openings in Trail Surfaces

Openings are gaps in the surface of a trail. Gaps include slots in a drainage grate and spaces between the planks on a puncheon, bridge, or boardwalk. Openings that are big enough for wheels, cane or crutch tips, or shoe heels to drop through or get stuck in are hazards that shouldn't exist in pedestrian routes. Openings up to ½ inch (13 millimeters) wide are permitted in trail surfaces. Elongated openings must be placed so that the long dimension is perpendicular or diagonal to the primary direction of travel (figure 120). Elongated openings less than ¼-inch (6.4 millimeters) wide may be used parallel to the dominant direction of travel (figure 121). This allows trail managers to place boards lengthwise along a boardwalk trail, as is often done in wetland areas.

Illustration of a boardwalk trail. The text on the illustration indicates the boards perpendicular to the direction of travel are each separated by no more than one-half inch of space.
Figure 120—The requirements for openings in the trail surface
that are perpendicular to the direction of travel.

Illustration of a boardwalk trail. The text on the illustration indicates the boards parallel to the direction of travel must be spaced less than one-quarter inch apart.
Figure 121—The requirements for openings in the trail surface that
are parallel to the direction of travel.

If there is a condition for departure, openings less than ¾ inch (19 millimeters) wide may be placed perpendicular or diagonal to the predominant direction of travel. This exception allows the use of boardwalk decking that needs more than ½-inch- (13-millimeter-) wide spacing between the planks to permit expansion and to allow water to drain.

If one or more conditions for departure prevent the trail from meeting the requirements above, compliance with the openings provision isn't required.

Edge Protection for Trails

Edge protection is a raised curb, wall, railing, or other projecting surface that defines the edge of a travel surface and helps keep people and assistive devices from accidentally falling off the edge. Edge protection is not required for accessibility on trails. However, if edge protection is provided on a trail to improve safety or for other reasons, it should be designed appropriately for the site and must be at least 3 inches (75 millimeters) high. This is higher than the 2-inch (50-millimeter) edge protection required by the ABAAS because objects less than 3 inches (75 millimeters) high aren't easy to see or detect in the outdoors. Such objects may become a tripping hazard, particularly since natural trail surfaces tend to be irregular. In the outdoors, people with limited vision who use canes tend to search higher than they do indoors (figure 122). They use the tactile change between the trail surface and the surrounding ground surface to distinguish between the edge and the surface of the trail. Holes, slots or other openings in the edge protection may be provided for drainage or other reasons.

Photo of a man using his cane to search the edge of the trail he is hiking.
Figure 122—A hiker searches the edge of a trail.

Signs for Trails

Local managers can decide whether to post signs on newly constructed or altered class 1, 2, or 3 hiking or pedestrian trails. If a local manager decides to post signs, they must meet the requirements explained below. Trail classes are explained in Understanding Trail Terminology.

Signs must be posted at the trailheads of newly constructed or altered class 4 or 5 trails and trail segments that are designed for hiker or pedestrian use, and at trailheads for trails that have been evaluated for accessibility. At a minimum, information on trailhead signs must include:

The last requirement is because tree blowdowns, flooding, or other events can make trails designed and constructed to FSTAG standards temporarily inaccessible until maintenance crews can clear the obstruction.

Where more extensive trail information such as an aerial map of the trail and related facilities is provided, the location of specific trail features and obstacles that do not comply with the FSTAG's technical provisions should be identified and a profile of the trail grade should be included.

If materials such as maps, brochures, fee envelopes, and so on need to be obtained from or filled out at a sign or kiosk, the sign or kiosk must be designed to meet the standard reach ranges of a person in a wheelchair in accordance with ABAAS section 308 as explained in Reach Ranges and Operability Requirements. In addition, 30- by 48-inch (760- by 1,220-millimeter) clear floor or ground spaces must be provided to allow for forward or side approach.

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