DesignStandards Hiker-Pedestrian.pdf

Design Parameters

Design Parameters are technical guidelines for the survey, design, construction, maintenance, and assessment of National Forest System trails, based on their Designed Use and Trail Class and consistent with their management intent

. Local deviations from any Design Parameter may be established based on trail-specific conditions, topography, or other factors, provided that the deviations are consistent with the general intent of the applicable Trail Class.

Designed Use

HIKER/PEDESTRIAN Trail Class 1 Trail Class 2 Trail Class 3 2 Trail Class 4 2 Trail Class 5 2

Design Tread Width

Wilderness (Single Lane)

0” – 12” 6” – 18” 12” – 24”

Exception: may be 36” – 48” at steep side slopes

18” – 24”

Exception: may be 36” – 48” at steep side slopes

Not applicable

Non-Wilderness (Single Lane)

0” – 12” 6” – 18” 18” – 36”

24” – 60”

36” – 72”

Non-Wilderness (Double Lane)

36” 36” 36” – 60” 48” – 72” 72” – 120”

Structures (Minimum Width)

18” 18” 18” 36” 36”

Design Surface3

Type Native, ungraded

May be continuously rough

Native, limited grading

May be continuously rough

Native with some onsite borrow or imported material where needed for stabilization, occasional grading

Intermittently rough

Native with improved sections of borrow or imported material, routine grading

Minor roughness

Likely imported material, routine grading

Uniform, firm, and stable

Protrusions ≤ 24”

Likely common and continuous

≤ 6”

May be common and continuous

≤ 3”

May be common, not continuous

≤ 3 ”

Uncommon, not continuous

No protrusions

Obstacles (Maximum Height)

24”

14”

10”

8”

No obstacles

Design Grade 3

Target Grade 5% – 25%

5% – 18% 3% – 12% 2% – 10% 2% – 5%

Short Pitch Maximum

40% 35% 25% 15% 5%

FSTAG: 5% – 12%

Maximum Pitch Density 20% – 40% of trail

20% – 30% of trail

10% – 20% of trail

5% – 20% of trail

0% – 5% of trail

10/16/2008

Designed Use

HIKER/PEDESTRIAN Trail Class 1 Trail Class 2 Trail Class 3 2 Trail Class 4 2 Trail Class 5 2

Design Cross Slope

Target Cross Slope Natural side slope

5% – 20% 5% – 10% 3% – 7% 2% – 3% (or crowned)

Maximum Cross Slope Natural side slope

25% 15% 10% 3%

Clearing

Height 6’

6’ – 7’ 7’ – 8’ 8’ – 10’ 8’ – 10’

Width ≥ 24”

Some vegetation may encroach into clearing area

24” – 48”

Some light vegetation may encroach into clearing area

36” – 60”

48” – 72”

60” – 72”

Shoulder Clearance 3” – 6”

6” – 12” 12” – 18” 12” – 18” 12” – 24”

Turn

Radius No minimum 2’ – 3’ 3’ – 6’ 4’ – 8’ 6’ – 8’

For definitions of Design Parameter attributes (e.g., Design Tread Width and Short Pitch Maximum) see FSH 2309.18, section 05.

Trail Classes 3, 4, and 5, in particular, have the potential to provide accessible passage. If assessing or designing trails for accessibility, refer to the Forest Service Trail Accessibility Guidelines (FSTAG) for more specific technical provisions and tolerances (FSM 2350).

The determination of trail-specific design grades, design surface, and other Design Parameters should be based upon soils, hydrological conditions, use levels, erosion potential, and other factors contributing to surface stability and overall sustainability of the trail.