Att 05_Trail Design Parameters.pdf

Trail Design Parameters Hiker/Pedestrian (FSH 2309.18, Section 23.11, Exhibit 01)

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.1 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 32 Trail Class 42 Trail Class 52

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 and occasional grading

Intermittently rough

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

Minor roughness

Likely imported material, and 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 Grade3

Target Grade 5% – 25% 5% – 18% 3% – 12% 2% – 10% 2% – 5%

Short Pitch Maximum

40% 35% 25% 15% 5%

FSTAG: 5% – 12%2

Maximum Pitch Density

20% – 40% of trail 20% – 30% of trail 10% – 20% of trail 5% – 20% of trail 0% – 5% of trail

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Designed Use HIKER/PEDESTRIAN Trail Class 1 Trail Class 2 Trail Class 32 Trail Class 42 Trail Class 52

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%

Design 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″ Design Turn

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

1 For definitions of Design Parameter attributes (for example, Design Tread Width and Short Pitch Maximum) see FSH 2309.18, Section 05.

2 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).

3 The determination of trail-specific Design Grade, 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.

Pack and Saddle (FSH 2309.18, Section 23.12, Exhibit 01)

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.1 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 PACK AND SADDLE Trail Class 1 Trail Class 2 Trail Class 3 Trail Class 4 Trail Class 5

Design Tread Width

Wilderness (Single Lane)

Typically not designed or actively managed for equestrians, although use may be allowed

12″ – 18″ May be up to 48″ along steep side slopes

48″ – 60″ or greater along precipices

18″ – 24″ May be up to 48″ along steep side slopes

48″ – 60″ or greater along precipices

24″ May be up to 48″ along steep side slopes

48″ – 60″ or greater along precipices

Typically not designed or actively managed for equestrians, although use may be allowed

Non-Wilderness (Single Lane)

12″ – 24″ May be up to 48″ along steep side slopes

48″ – 60″ or greater along precipices

18″ – 48″ 48″ – 60″ or greater along precipices

24″ – 96″ 48″ – 60″ or greater along precipices

Non-Wilderness (Double Lane)

60″ 60″ – 84″ 84″ – 120″

Structures (Minimum Width)

Other than bridges: 36″ Bridges without handrails: 60″ Bridges with handrails:

84″ clear width

Other than bridges: 36″ Bridges without handrails: 60″ Bridges with handrails:

84″ clear width

Other than bridges: 36″ Bridges without handrails: 60″ Bridges with handrails:

84″ clear width

Design Surface2

Type Native, with limited grading

May be frequently rough

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

Intermittently rough

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

Minor roughness

Protrusions ≤ 6″ May be common and continuous

≤ 3″ May be common, not continuous

≤ 3″ Uncommon, not continuous

Obstacles (Maximum Height)

12″ 6″ 3″ e s ig n P a ra m e

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Designed Use PACK AND SADDLE Trail Class 1 Trail Class 2 Trail Class 3 Trail Class 4 Trail Class 5

Design Grade2

Target Grade Typically not designed or actively managed for equestrians, although use may be allowed

5% – 20% 3% – 12% 2% – 10% Typically not designed or actively managed for equestrians, although use may be allowed

Short Pitch Maximum

30% 20% 15%

Maximum Pitch Density

15% – 20% of trail 5% – 15% of trail 5% – 10% of trail

Design Cross Slope

Target Cross Slope

5% – 10% 3% – 5% 0% – 5%

Maximum Cross Slope

10% 8% 5%

Design Clearing

Height 8′ – 10′ 10′ 10′ – 12′ Width 72″

Some light vegetation may encroach into clearing area

72″ – 96″ 96″

Shoulder Clearance

6″ – 12″ Pack clearance:

36″ x 36″

12″ – 18″ Pack clearance:

36″ x 36″

12″ – 18″ Pack clearance:

36″ x 36″

Design Turn

Radius 4′ – 5′ 5′ – 8′ 6′ – 10′

1 For definitions of Design Parameter attributes (for example, Design Tread Width and Short Pitch Maximum) see FSH 2309.18, Section 05.

2 The determination of trail-specific Design Grade, Design Surface, and other Design Parameters should be based upon soils, hydrological conditions, use levels, erosion potential, and

Bicycle (FSH 2309.18, Section 23.13, Exhibit 01)

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.1 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 BICYCLE Trail Class 1 Trail Class 2 Trail Class 3 Trail Class 4 Trail Class 5

Design Tread Width

Single Lane 6″ – 12″ 12″ – 24″ 18″ – 36″ 24″ – 48″ 36″ – 60″ Double Lane 36″ – 48″ 36″ – 48″ 36″ – 48″ 48″ – 84″ 72″ – 120″ Structures (Minimum Width)

18″ 18″ 36″ 48″ 60″

Design Surface2

Type Native, ungraded

May be continuously rough

Sections of soft or unstable tread on grades < 5% may be common and continuous

Native, with limited grading

May be continuously rough

Sections of soft or unstable tread on grades < 5% may be common

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

Intermittently rough

Sections of soft or unstable tread on grades < 5% may be present, but not common

Native, with improved sections of borrow or imported materials and routine grading

Stable, with minor roughness

Likely imported material and routine grading

Uniform, firm, and stable

Protrusions ≤ 24″ Likely common and continuous

≤ 6″ May be common and continuous

≤ 3″ May be common, but not continuous

≤ 3″ Uncommon and not continuous

No protrusions

Obstacles (Maximum Height)

24″ 12″ 10″ 8″ No obstacles

Design Grade2

Target Grade 5% – 20% 5% – 12% 3% – 10% 2% – 8% 2% – 5%

Short Pitch Maximum

30%

50% on downhill segments only

25%

35% on downhill segments only

15% 10% 8%

Maximum Pitch Density

20% – 30% of trail 10% – 30% of trail 10% – 20% of trail 5% – 10% of trail 0% – 5% of trail

Design Cross Slope

Target Cross Slope

5% – 10% 5% – 8% 3% – 8% 3% – 5% 2% – 3%

Maximum Cross Slope

10% 10% 8% 5% 5% e s ig n P a ra m e

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Designed Use BICYCLE Trail Class 1 Trail Class 2 Trail Class 3 Trail Class 4 Trail Class 5

Design Clearing

Height 6′ 6′ – 8′ 8′ 8′ – 9′ 8′ – 9′ Width 24″ – 36″

Some vegetation may encroach into clearing area

36″ – 48″ Some light vegetation may encroach into clearing area

60″ – 72″ 72″ – 96″ 72″ – 96″

Shoulder Clearance

0″ – 12″ 6″ – 12″ 6″ – 12″ 6″ – 18″ 12″ – 18″

Design Turn

Radius 2′ – 3′ 3′ – 6′ 4′ – 8′ 8′ – 10′ 8′ – 12′

1 For definitions of Design Parameter attributes (for example, Design Tread Width and Short Pitch Maximum) see FSH 2309.18, Section 05.

2 The determination of trail-specific Design Grade, Design Surface, and other Design Parameters should be based upon soils, hydrological conditions, use levels, erosion potential, and

Motorcycle (FSH 2309.18, Section 23.21, Exhibit 01)

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.1 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 MOTORCYCLE Trail Class 1 Trail Class 2 Trail Class 3 Trail Class 4 Trail Class 5

Design Tread Width

Single Lane Typically not designed or actively managed for motorcycles, although use may be allowed

8″ – 24″ 18″ – 36″ 24″ – 48″ Typically not designed or actively managed for motorcycles, although use may be allowed

Double Lane 48″ 48″ – 60″ 60″ – 72″ Structures (Minimum Width)

36″ 48″ 48″

Design Surface2

Type Native, with limited grading

May be continuously rough

Sections of soft or unstable tread on grades < 5% may be common and continuous

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

Intermittently rough

Sections of soft or unstable tread on grades < 5% may be present

Native, with imported materials for tread stabilization likely and routine grading

Minor roughness

Sections of soft tread not common

Protrusions ≤ 6″ May be common and continuous

≤ 3″ May be common, but not continuous

≤ 3″ Uncommon and not continuous

Obstacles (Maximum Height)

18″ May be common or placed for increased challenge

12″ Common and left for increased challenge

3″ Uncommon

Design Grade2

Target Grade 10% – 25% 5% – 20% 3% – 10%

Short Pitch Maximum

40% 25% 15%

Maximum Pitch Density

20% – 40% of trail 15% – 30% of trail 10% – 20% of trail e s ig n P a ra m e

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Designed Use MOTORCYCLE Trail Class 1 Trail Class 2 Trail Class 3 Trail Class 4 Trail Class 5

Design Cross Slope

Target Cross Slope

Typically not designed or actively managed for motorcycles, although use may be allowed

5% – 10% 5% – 8% 3% – 5% Typically not designed or actively managed for motorcycles, although use may be allowed

Maximum Cross Slope

15% 10% 10%

Design Clearing

Height 6′ – 7′ 6′ – 8′ 8′ – 10′ Width (On steep side hills, increase clearing on uphill side by 6″ – 12″)

36″ – 48″ Some light vegetation may encroach into clearing area

48″ – 60″ 60″ – 72″

Shoulder Clearance

6″ – 12″ 12″ – 18″ 12″ – 24″

Design Turn

Radius 3′ – 4′ 4′ – 6′ 5′ – 8′

1 For definitions of Design Parameter attributes (for example, Design Tread Width and Short Pitch Maximum) see FSH 2309.18, Section 05.

2 The determination of trail-specific Design Grade, Design Surface, and other Design Parameters should be based upon soils, hydrological conditions, use levels, erosion potential, and

All-Terrain Vehicle (FSH 2309.18, Section 23.22, Exhibit 01)

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.1 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 ALL-TERRAIN VEHICLE Trail Class 1 Trail Class 2 Trail Class 3 Trail Class 4 Trail Class 5

Design Tread Width

Single Lane Typically not designed or actively managed for ATVs, although use may be allowed

48″ – 60″ 60″ 60″ – 72″ Typically not designed or actively managed for ATVs, although use may be allowed

Double Lane 96″ 96″ – 108″ 96″ – 120″ Structures (Minimum Width)

60″ 60″ 60″

Design Surface2

Type Native, with limited grading

May be continuously rough

Sections of soft or unstable tread on grades < 5% may be common and continuous

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

Intermittently rough

Sections of soft or unstable tread on grades < 5% may be present

Native, with imported materials for tread stabilization likely and routine grading

Minor roughness

Sections of soft tread uncommon

Protrusions ≤ 6″ May be common and continuous

≤ 3″ May be common, but not continuous

≤ 3″ Uncommon and not continuous

Obstacles (Maximum Height)

12″ May be common or placed for increased challenge

6″ May be common and left for increased challenge

3″ Uncommon

Design Grade2

Target Grade 10% – 25% 5% – 15% 3% – 10%

Short Pitch Maximum

35% 25% 15%

Maximum Pitch Density

20% – 40% of trail 15% – 30% of trail 10% – 20% of trail e s ig n P a ra m e

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Designed Use ALL-TERRAIN VEHICLE Trail Class 1 Trail Class 2 Trail Class 3 Trail Class 4 Trail Class 5

Design Cross Slope

Target Cross Slope

Typically not designed or actively managed for ATVs, although use may be allowed

5% – 10% 3% – 8% 3% – 5% Typically not designed or actively managed for ATVs, although use may be allowed

Maximum Cross Slope

15% 10% 8%

Design Clearing

Height 6′ – 7′ 6′ – 8′ 8′ – 10′ Width (On steep side hills, increase clearing on uphill side by 6″ – 12″)

60″ Some light vegetation may encroach into clearing area

60″ – 72″ 72″ – 96″

Shoulder Clearance

0″ – 6″ 6″ – 12″ 12″ – 18″

Design Turn

Radius 6′ – 8′ 8′ – 10′ 8′ – 12′

1 For definitions of Design Parameter attributes (for example, Design Tread Width and Short Pitch Maximum) see FSH 2309.18, Section 05.

2 The determination of trail-specific Design Grade, Design Surface, and other Design Parameters should be based upon soils, hydrological conditions, use levels, erosion potential, and

Four-Wheel Drive Vehicle > 50″ (FSH 2309.18, Section 23.23, Exhibit 01)

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.1 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 FOUR-WHEEL DRIVE VEHICLE > 50″ Trail Class 1 Trail Class 2 Trail Class 3 Trail Class 4 Trail Class 5

Design Tread Width

Single Lane Typically not designed or actively managed for 4WD vehicles > 50″, although use may be allowed

72″ – 84″ 72″ – 96″ 96″ – 120″ Typically not designed or actively managed for 4WD vehicles > 50″, although use may be allowed

Double Lane 16′ 16′ 16′ Structures (Minimum Width)

96″ 96″ 96″

Design Surface2

Type Native, with limited grading

May be continuously rough

Sections of soft or unstable tread on grades < 5% may be common and continuous

Native, with some on-site borrow or imported material where needed for stabilization and occasional grading

Intermittently rough

Sections of soft or unstable tread on grades < 5% may be present

Native, with imported materials for tread stabilization likely and routine grading

Minor roughness

Sections of soft tread uncommon

Protrusions ≤ 12″ May be common and continuous

≤ 8″ May be common and continuous

≤ 4″ May be common and continuous

Obstacles (Maximum Height)

36″ May be common or placed for increased challenge

24″ Common and left for increased challenge

12″ Uncommon

Design Grade2

Target Grade 10% – 21% 5% – 18% 5% – 12%

Short Pitch Maximum 25% 20% 15%

Maximum Pitch Density 20% – 30% of trail 10% – 20% of trail 5% – 10% of trail e s ig n P a ra m e

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Designed Use FOUR-WHEEL DRIVE VEHICLE > 50″ Trail Class 1 Trail Class 2 Trail Class 3 Trail Class 4 Trail Class 5

Design Cross Slope

Target Cross Slope Typically not designed or actively managed for 4WD vehicles > 50″, although use may be allowed

8% – 15% 5% – 12% 5% – 8% Typically not designed or actively managed for 4WD vehicles > 50″, although use may be allowed

Maximum Cross Slope 15% 12% 8%

Design Clearing

Height 6′ – 8′ 6′ – 8′ 8′ – 10′ Width 72″ – 84″

Some light vegetation may encroach into clearing area

72″ – 96″ 96″ – 144″

Shoulder Clearance 0″ – 6″ 6″ – 12″ 12″ – 18″ Design Turn

Radius 10′ – 15′ 15′ – 20′ 20′ – 30′

1 For definitions of Design Parameter attributes (for example, Design Tread Width and Short Pitch Maximum) see FSH 2309.18, Section 05.

2 The determination of trail-specific Design Grade, Design Surface, and other Design Parameters should be based upon soils, hydrological conditions, use levels, erosion potential, and

Cross-Country Ski (FSH 2309.18, Section 23.31, Exhibit 01)

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.1 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 CROSS-COUNTRY SKI Trail Class 1 Trail Class 2 Trail Class 3 Trail Class 4 Trail Class 5

Design Tread Width

Single Lane Typically not designed or actively managed for cross-country skiing, although use may be allowed

2′ – 4′ Typically not groomed

6′ – 8′ Or width of grooming equipment

8′– 10′ Or width of grooming equipment

Typically not designed or actively managed for cross-country skiing, although use may be allowed

Double Lane 6′ – 8′ 8′ – 12′ 12′ – 16′ Structures (Minimum Width)

36″ 36″ 36″

Design Surface2

Type Generally no machine grooming

May receive occasional machine grooming for snow compaction and track setting

Regular machine grooming for snow compaction and track setting

Protrusions No protrusions No protrusions No protrusions

Obstacles (Maximum Height)

12″ Uncommon

8″ Uncommon (no obstacles if machine groomed)

No obstacles

Design Grade2

Target Grade 5% – 15% 2% – 10% 0% – 8%

Short Pitch Maximum

25% 20% 12%

Maximum Pitch Density

10% – 20% of trail 5% – 15% of trail 0% – 10% of trail

Design Cross Slope

Target Cross Slope

0% – 10% 0% – 5% 0% – 5%

Maximum Cross Slope (For up to 50″)

20% 15% 10% e s ig n P a ra m e

C ro s s -C o u n try S k i (F

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Designed Use CROSS-COUNTRY SKI Trail Class 1 Trail Class 2 Trail Class 3 Trail Class 4 Trail Class 5

Design Clearing

Height (Above normal maximum snow level)

Typically not designed or actively managed for cross-country skiing, although use may be allowed

6′ – 8′ 8′ Or height of grooming equipment

8′ – 10′ Typically not designed or actively managed for cross-country skiing, although use may be allowed

Width 24″ – 60″ Light vegetation may encroach into clearing area

72″ – 120″ Light vegetation may encroach into clearing area

96″ – 168″ Widen clearing at turns or if increased sight distance needed

Shoulder Clearance

0″ – 6″ 0″ – 12″ 0″ – 24″

Design Turn

Radius 8′ – 10′ 15′ – 20′ Or to accommodate grooming equipment

≥ 25′

1 For definitions of Design Parameter attributes (for example, Design Tread Width and Short Pitch Maximum) see FSH 2309.18, Section 05.

2 The determination of trail-specific Design Grade, Design Surface, and other Design Parameters should be based upon soils, hydrological conditions, use levels, erosion potential, and

Snowshoe (FSH 2309.18, Section 23.32, Exhibit 01)

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.1 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 SNOWSHOE Trail Class 1 Trail Class 2 Trail Class 3 Trail Class 4 Trail Class 5

Design Tread Width

Single Lane Typically not designed or actively managed for snowshoe, although use may be allowed

36″ 36″ – 48″ 36″ – 60″ Typically not designed or actively managed for snowshoe, although use may be allowed

Double Lane 60″ 72″ 72″ – 96″ Structures (Minimum Width)

36″ 48″ 48″

Design Surface2

Type Generally no machine grooming

May receive occasional machine grooming for snow compaction

Likely to receive occasional machine grooming for snow compaction

Protrusions No protrusions No protrusions No protrusions

Obstacles (Maximum Height)

12″ Uncommon

8″ Uncommon (no obstacles if machine groomed)

No obstacles

Design Grade2

Target Grade 10% – 20% 5% – 15% 0% – 10%

Short Pitch Maximum

30% 20% 15%

Maximum Pitch Density

5% – 20% of trail 5% – 25% of trail 0% – 10% of trail

Design Cross Slope

Target Cross Slope

0% – 10% 0% – 5% 0% – 5%

Maximum Cross Slope

20% 15% 10% e s ig n P a ra m e

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Designed Use SNOWSHOE Trail Class 1 Trail Class 2 Trail Class 3 Trail Class 4 Trail Class 5

Design Clearing

Height (Above normal maximum snow level)

Typically not designed or actively managed for snowshoe, although use may be allowed

6′ – 8′ 8′ 8′ – 10′ Typically not designed or actively managed for snowshoe, although use may be allowedWidth 48″

Some light vegetation may encroach into clearing area

72″ Light vegetation may encroach into clearing area

72″ – 96″

Shoulder Clearance

0″ 12″ 12″ – 24″

Design Turn

Radius 3′ – 4′ 3′ – 6′ 4′ – 8′ Or to accommodate grooming equipment

1 For definitions of Design Parameter attributes (for example, Design Tread Width and Short Pitch Maximum) see FSH 2309.18, Section 05.

2 The determination of trail-specific Design Grade, Design Surface, and other Design Parameters should be based upon soils, hydrological conditions, use levels, erosion potential, and

Snowmobile (FSH 2309.18, Section 23.33, Exhibit 01)

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.1 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 SNOWMOBILE Trail Class 1 Trail Class 2 Trail Class 3 Trail Class 4 Trail Class 5

Design Tread Width

Single Lane Typically not designed or actively managed for snowmobiles, although use may be allowed

4′ – 6′ Typically not groomed

6′ – 8′ Or width of grooming equipment

On turns with tight radius, increase groomed width to ≥ 10′

8′ – 10′ Or minimum width of grooming equipment

On turns with tight radius, increase groomed width to ≥ 12′

Typically not designed or actively managed for snowmobiles, although use may be allowed

Double Lane 10′ Typically not groomed

10′ – 12′ 12′ – 20′

Structures (Minimum Width)

6′ 12′ 18′

Design Surface2

Type Generally no machine grooming

Commonly rough and bumpy

May receive occasional machine grooming for snow compaction and conditioning

Frequently rough and bumpy

Regular machine grooming for snow compaction and conditioning

Commonly smooth

Protrusions No protrusions No protrusions No protrusions

Obstacles (Maximum Height)

12″ Uncommon

6″ Uncommon (no obstacles if machine groomed)

No obstacles

Design Grade2

Target Grade 0% – 12% 0% – 10% 0% – 8%

Short Pitch Maximum

35% 25% 20%

Maximum Pitch Density

15% – 30% of trail 10% – 20% of trail 5% – 10% of trail e s ig n P a ra m e

S n o w m o b ile (F

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Designed Use SNOWMOBILE Trail Class 1 Trail Class 2 Trail Class 3 Trail Class 4 Trail Class 5

Design Cross Slope

Target Cross Slope

Typically not designed or actively managed for snowmobiles, although use may be allowed

0% – 10% 0% – 5% 0% Typically not designed or actively managed for snowmobiles, although use may be allowed

Maximum Cross Slope

15% 10% 5%

Design Clearing

Height (Above normal maximum snow level)

6′ 6′ – 8′ Provide sufficient clearance for grooming equipment

8′ – 12′ Provide sufficient clearance for grooming equipment

Width 6′ – 12′ Some light vegetation may encroach into clearing area

8′ – 14 ′ Light vegetation may encroach into clearing area

10′ – 22′ Widen clearing at turns or if increased sight distance needed

Shoulder Clearance

6″ – 12″ 12″ – 18″ 12″ – 24″

Design Turn

Radius 8′ – 10′ 15′ – 20′ Or sufficient radius for grooming equipment

25′ – 50′

1 For definitions of Design Parameter attributes (for example, Design Tread Width and Short Pitch Maximum) see FSH 2309.18, Section 05.

2 The determination of trail-specific Design Grade, Design Surface, and other Design Parameters should be based upon soils, hydrological conditions, use levels, erosion potential, and