trail attributes

objective characteristics

trail attributes

objective characteristics

trail length

Trail length helps users determine timing and difficulty when deciding on their ideal path. The length of surface found in between stations is recorded in the preferred metric (mi/km).

grade

Running Slope. The slope that is parallel to the direction of travel.
Architectural Barriers Act (ABA) Standards (2015), pg 16

Running Slope (Grade). The ascent or descent of a trail segment expressed as a percentage of its length, which is the difference in elevation of a section of a trail measured parallel to the predominant direction of travel. This may be expressed as a ratio of vertical distance to horizontal distance or as the percentage of change in elevation.
Forest Service Trail Accessibility Guidelines (FSTAG) (2013), pg 8

technical requirements

1017.7 Slopes. The slopes of trails shall comply with 1017.7.

1017.7.1 Maximum Running Slope and Segment Length. Not more than 30 percent of the total length of a trail shall have a running slope steeper than 1:12 (8.33%). The running slope of any segment of a trail shall not be steeper than 1:8 (12%). Where the running slope of a segment of a trail is steeper than 1:20 (5%), the maximum length of the segment shall be in accordance with Table 1017.7.1, and a resting interval complying with 1017.8 shall be provided at the top and bottom of each segment.

Table 1017.7.1 Maximum Running Slope and Segment Length

Running Slope of Trail Segment Maximum Length of Segment
Steeper thanBut not Steeper than 
1:20 (5%)1:12 (8.33%)200 feet (61 m)
1:12 (8.33%)1:10 (10%)30 feet (9 m)
1:10 (10%)1:8 (12%)10 feet (3050 mm)

Advisory 1017.7.1 Maximum Running Slope and Segment Length. Gradual running slopes on trails are more useable by individuals with disabilities. Where the terrain results in steeper running slopes, resting intervals are required more frequently. Where running slopes are less severe, resting intervals are permitted to be further apart.

1017.8 Resting Intervals. Resting intervals shall comply with 1017.8.

1017.8.1 Length. The resting interval length shall be 60 inches (1525 mm) long minimum.

1017.8.2 Width. Where resting intervals are provided within the trail tread, resting intervals shall be at least as wide as the widest segment of the trail tread leading to the resting interval. Where resting intervals are provided adjacent to the trail tread, the resting interval clear width shall be 36 inches (915 mm) minimum.

1017.8.3 Slope. Resting intervals shall have slopes not steeper than 1:48 in any direction.

EXCEPTION: Where the surface is other than concrete, asphalt, or boards, cross slopes not steeper than 1:20 shall be permitted when necessary for drainage.

1017.8.4 Turning Space. Where resting intervals are provided adjacent to the trail tread, a turning space complying with 304.3.2 shall be provided. Vertical alignment between the trail tread, turning space, and resting interval shall be nominally planar.

7.4.3 Slope.
Trail running slopes (grades) and cross slopes shall comply with sections 7.4.3.1 and 7.4.3.2.

7.4.3.1 Running Slope (Grade). The running slope (grade) of trail segments shall comply with this section and shall be consistent over the distances cited.

    • Trail running slope (grade) of up to 1:20 (5 percent) is permitted for any distance.
    • The running slope of any segment of a trail shall not be steeper than 1:8 (12 percent).
    • No more than 30 percent of the total trail length may exceed a running slope (grade) of 1:12 (8.33 percent).
    • Where the running slope (grade) of a segment of a trail is steeper than 1:20 (5 percent), the maximum length of the segment shall be in accordance with Table 7.4.3.1, and a resting interval complying with 7.4.4 shall be provided at each end of the segment.

Table 7.4.3.1 Running Slope (Grade) and Resting Intervals

Running Slope of Trail Segment Maximum Length of Segment
Steeper thanBut not Steeper thanBetween Resting Intervals
1:20 (5%)1:12 (8.33%)200 feet (61 m)
1:12 (8.33%)1:10 (10%)30 feet (9 m)
1:10 (10%)1:8 (12%)10 feet (3050 mm)

 

7.4.4 Resting Intervals.
Resting intervals shall comply with 7.4.4. Where the trail grade exceeds 1:20 (5 percent), resting intervals shall be provided as specified in Table 7.4.3.1.

7.4.4.1 Length. The resting interval length shall be 60 inches (1525 mm) long minimum.

7.4.4.2 Width. Where resting intervals are provided within the trail tread, resting intervals shall be at least as wide as the widest segment of the trail tread leading to the resting interval. Where resting intervals are provided adjacent to the trail tread, the resting interval clear width shall be 36 inches (915 mm) minimum.

7.4.4.3 Slope. The slope of a resting interval shall not exceed 1:20 (5 percent) in any direction. Where the surface is paved or is elevated above the natural ground, the slope shall not be steeper than 1:48 (2 percent) in any direction.

7.4.4.4 Turning Space. Where resting intervals are provided adjacent to the trail tread, a turning space complying with ABAAS section 304.3.2 shall be provided. Vertical alignment between the trail tread, turning space, and resting interval shall be nominally level. The trail tread, turning space, and resting interval may overlap.

grade data

Objective information about the typical and maximum grade is very useful to all user groups, especially mountain bike riders and persons with mobility limitations, including older persons and those that use canes, crutches, walkers or wheelchairs. 

Information about the maximum grade sections found on a trail is used to add detailed information to maps. The typical and maximum grades are displayed with the grade symbol to convey this pertinent information on TAI SignPosts and trailhead signage.

assessing grade

The average grade between two designated stations along the trail is measured with a clinometer or inclinometer. These measurements are then used to compute the typical grade for the entire trail. Short, steep sections are measured with a SmartTool™ with SmartFeet and recorded as maximum grade sections. The SmartTool™ level is 24 inches in length and thus measures the grade as it would be experienced over the course of a single stride, or by a stroller or wheelchair.

cross slope

Cross Slope. The slope that is perpendicular to the direction of travel.
Architectural Barriers Act (ABA) Standards (2015), pg 14

Cross Slope. The percentage of rise to length, which is the difference in elevation, when measuring the trail tread from edge to edge perpendicular to the direction of travel This may be expressed as the percentage of change in elevation or as a ratio of vertical distance to horizontal distance.
Forest Service Trail Accessibility Guidelines (FSTAG) (2013), pg 8

technical requirements

1017.7.2 Cross Slope. The cross slope shall be not be steeper than 1:48.

EXCEPTION: Where the surface is other than concrete, asphalt, or boards, cross slopes not steeper than 1:20 shall be permitted when necessary for drainage.

7.4.3.2 Cross Slope. The cross slope shall not exceed 1:20 (5 percent). Where the surface is paved or is elevated above the natural ground, the cross slope shall not be steeper than 1:48 (2 percent).

cross slope data

Cross-slope information is most useful to wheelchair users. Wheelchairs are very difficult to drive or maneuver on steep cross slopes.

Information about cross slope is used to add detailed information to maps. The typical and maximum cross slopes are displayed with the cross-slope symbol to convey this pertinent information on TAI SignPosts and trailhead signage.

assessing cross slope

Cross slope is measured at designated stations along the trail with a 24-inch inclinometer along the best path of travel. These measurements are then used to compute the typical cross slope for the entire trail. Similar to maximum grade, steep cross slope sections are measured with an inclinometer and recorded as maximum cross slope sections.

tread width

Forest Service Trail Accessibility Guidelines (FSTAG) (2013), pg 9:

Tread Width. The visible trail surface measured perpendicular to the direction of travel.

Clear Tread Width. The width of the usable trail tread and adjacent usable surface.
Minimum Tread Width. The width of the usable part of the tread width at the narrowest point on a trail.
Minimum Trail Width. The width of the trail tread and the adjacent usable surface at the narrowest point on a trail.

technical requirements

1017.3 Clear Tread Width. The clear tread width of trails shall be 36 inches (915 mm) minimum.

1017.4 Passing Spaces. Trails with a clear tread width less than 60 inches (1525 mm) shall provide passing spaces complying with 1017.4 at intervals of 1000 feet (300 m) maximum. Where the full length of a trail does not fully comply with 1017, a passing space shall be located at the end of the trail segment that fully complies with 1017. Passing spaces and resting intervals shall be permitted to overlap.

Advisory 1017.4 Passing Spaces. Entities should consider providing either a 60 inches (1525 mm) minimum clear tread width or passing spaces at shorter intervals if the clear tread width is less than 60 inches (1525 mm), where a trail is:

    • Heavily used; or
    • A boardwalk or otherwise not at the same level as the ground surface adjoining the trail.

Where the full length of the trail does not fully comply with 1017, locating a passing space at the end of the trail segment that fully complies with 1017 enables a person who uses a mobility device to turn and exit the trail.

1017.4.1 Size. The passing space shall be either:

    1. A space 60 inches (1525 mm) minimum by 60 inches (1525 mm) minimum; or
    2. The intersection of two trails providing a T-shaped space complying with 304.3.2 where the base and the arms of the T-shaped space extend 48 inches (1220 mm) minimum beyond the intersection. Vertical alignment at the intersection of the trails that form the T-shaped space shall be nominally planar.

Advisory 1017.4.1 Size. Where the passing space is the intersection of two trails, the intersection must be as flat as possible so that all of the wheels of a mobility device touch the ground when turning into and out of the passing space.

7.4.2 Clear Tread Width.
The clear tread width of the trail shall be at least 36 inches (915 mm).

EXCEPTION: Where a condition for an exception prevents achieving the required width, the clear tread width may be reduced to 32 inches (815 mm) minimum. If the condition for an exception prevents achieving the reduced width of 32 inches, comply to the extent practicable.

7.4.5 Passing Spaces.
Trails with a clear tread width less than 60 inches (1525 mm) shall provide passing spaces complying with 7.4.5 at intervals of 1000 feet (300 m) maximum. A passing space must also be provided at the end of any segment of trail that meets the requirements of 7.4, if the full length of the trail does not meet the requirements. Passing spaces and resting intervals may coincide or overlap.

7.4.5.1 Size. The passing space shall be either:

    • A space 60 inches (1525 mm) minimum by 60 inches (1525 mm) minimum; or
    • The intersection of two trails providing a T-shaped space complying with ABAAS section 304.3.2 where the base and the arms of the T-shaped space extend 48 inches (1220 mm) minimum beyond the intersection. Vertical alignment at the intersection of the trails that form the T shaped space shall be nominally level.

7.4.5.2 Slope. The cross slope of a passing space shall not exceed 1:20 (5 percent) in any direction.

7.4.5.3 Non-complying Segment Ends. Where a segment of the trail does not comply with 7.4, a passing space shall be located at the end of each adjacent trail segment that does comply with 7.4.

tread width data

Objective information about the width of the trail and the locations of the narrowest sections is critical for people who use mobility devices such as strollers, walkers, and wheelchairs. The average manual wheelchair has a wheelbase width of less than 28 inches. If a trail narrows to 26 inches, persons in a 28-inch wheelchair will know that they will not be able to venture past this point unless they are capable of transferring out of their chair and maneuvering their chair through this narrow location. If the width of the trail is disclosed, mobility device users will be able to determine before embarking on a trail exactly how far they will be able to hike and whether they will be able to reach their destination.

assessing tread width

A tape measure is used to measure the width of the trail. The minimum tread width, or “beaten path,” is measured at each station and is used to calculate the typical tread width. The minimum amount of usable passage space between stations, or minimum clearance width, is also measured.

surface type & quality

Forest Service Trail Accessibility Guidelines (FSTAG) (2013), pg 8-9:

Surface. The top layer of a trail.

Firm. A firm surface resists deformation by indentations. During the planning process, firmness must be evaluated for noticeable distortion or compression during the seasons for which the surface is managed, under normally occurring weather conditions.
Stable. A surface is not permanently affected by expected weather conditions and can sustain normal wear and tear from the expected use(s) of the area, between planned maintenance.

technical requirements

1017.2 Surface. The surface of trails, passing spaces, and resting intervals shall be firm and stable.

Advisory 1017.2 Surface. A firm trail surface resists deformation by indentations. A stable trail surface is not permanently affected by expected weather conditions and can sustain normal wear and tear from the expected uses between planned maintenance.

7.4.1 Surface.
The trail tread surface, including resting intervals and passing spaces, shall be both firm and stable.

surface type & quality data

The level of firmness and stability of a trail surface is usually the greatest factor affecting the accessibility of a trail. Firmness and stability will determine if a user can even walk or roll across the surface of the trail. A visual range can be provided for both firmness and stability.

assessing surface type & quality

The type of surface found in between stations is recorded, as well as a description of its characteristics.

While a simple method using one’s heel can subjectively estimate the firmness and stability of a surface, objective surface assessment requires more precise and advanced testing. The Rotational Penetrometer (RP) 100 Series is the perfect tool for testing the surface quality of a trail. Shipping a reconstructed representation of a trail surface to an off-site test lab for surface testing is impractical and, most likely, impossible. In contrast, RP readings been proven to correlate with ASTM F1951 surface testing results, providing accurate and reliable surface quality measurements. Portable, precise, and durable, the RP accurately and objectively measures surface quality for firmness and stability on-site.

obstructions

Any obstructions to the path of travel, whether within or protruding into the path of travel are recorded. Such features often include, but are not limited to rocks, ruts, or roots.

technical requirements

1017.5 Tread Obstacles. Tread obstacles on trails, passing spaces, and resting intervals shall not exceed 1/2 inch (13 mm) in height measured vertically to the highest point.

EXCEPTION: Where the surface is other than asphalt, concrete, or boards, tread obstacles shall be permitted to not exceed 2 inches (50 mm) in height measured vertically to the highest point.

Advisory 1017.5 Tread Obstacles. The vertical alignment of joints in concrete, asphalt, or board surfaces can be tread obstacles. Natural features such as tree roots and rocks within the trail tread can also be tread obstacles. Where possible, tread obstacles that cross the full width of the trail tread should be separated by a distance of 48 inches (1220 mm) minimum.

1017.6 Openings. Openings in the surface of trails, passing spaces, and resting intervals shall not allow the passage of a sphere more than 1/2 inch (13 mm) in diameter.

Advisory 1017.6 Openings. Elongated openings should be placed so that the long dimension is perpendicular, or as close to perpendicular as possible, to the dominant direction of travel.

1017.9 Protruding Objects. Constructed elements on trails, passing spaces, and resting intervals shall comply with 307.

Advisory 1017.9 Protruding Objects. Protruding objects on trails, passing spaces, and resting intervals can be hazardous for individuals who are blind or have low vision. Signs and other post mounted objects are examples of constructed elements that can be protruding objects.

7.4.6 Tread Obstacles.
Tread obstacles on trails shall not exceed 2 inches (50 mm) in height measured vertically to the highest point. Where the trail surface is paved or is elevated above the natural ground, tread obstacles shall not exceed ½ inch (13 mm) in height measured vertically to the highest point.

7.4.7 Openings.
Openings in trail tread surfaces, trail resting spaces, and trail passing spaces shall be small enough to prevent passage of a 1/2 inch- (13 mm-) diameter sphere. Where possible, elongated openings should be placed perpendicular, or as close to perpendicular as possible, to the dominant direction of travel.

Exception. Where openings that do not permit the passage of a ½ inch (6.4 mm) sphere cannot be provided due to a condition for an exception, openings that do not permit passage of a ¾ inch (19 mm) sphere shall be permitted.

7.4.8 Protruding Objects.
Constructed features, including signs, shall not extend into the trail tread more than 4 inches (100 mm) between 27 inches (685 mm) and 80 inches (2030 mm) above the surface of the trail.

additional features

Besides these five main areas of focus, other features along the way can be recorded and/or assessed typically for size, material, and quantity. More in-depth feature assessment procedures are available through the Developed Outdoor Recreation Assessment Process (DORAP). Such features may include trailhead signs, trash cans, water spouts, benches, restrooms, and many more.

technical requirements

For information regarding technical requirements of additional features, please see chapter 10: Recreation Facilities in the Architectural Barriers Act Accessibility Standards (ABAAS) or see the US Forest Service Outdoor Recreation Accessibility Guidelines (FSORAG).