5-5 2026 Holbrook USFS Trail Design Parameters.pdf
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About this file
This file contains technical design parameters established by the United States Forest Service for sustainable trail construction and maintenance across multiple user types and trail classifications. The document provides comprehensive guidelines for designing hiking/pedestrian trails, pack and saddle trails, bicycle trails, motorcycle trails, all-terrain vehicle trails, four-wheel drive vehicle trails, cross-country ski trails, snowshoe trails, and snowmobile trails, each categorized into five trail classes. For each trail type and class combination, the parameters specify design tread width, design surface type, protrusions, obstacles, design grade, cross slope, clearing height and width, shoulder clearance, and design turn radius. These parameters serve as technical standards for survey, design, construction, maintenance, and assessment of National Forest System trails based on their designed use and management intent. The guidelines allow for local deviations from design parameters when based on trail-specific conditions, topography, or other factors, provided deviations remain consistent with the general intent of the applicable trail class. The document references FSH 2309.18 sections and the Forest Service Trail Accessibility Guidelines (FSTAG) for additional technical provisions and tolerances.
The design parameters detailed in this document are applicable to the 2026 Big Rock Hiking Trail Project in Bountiful City, Utah, which involves construction of two separate hiking trail segments on United States Forest Service-managed public lands in the Mueller Park area. Schedule 1 consists of approximately 250 feet of trail with significant rock retaining and tread armoring work, while Schedule 2 comprises approximately 1.1 miles of trail with limited rock work. Both segments are to be constructed as Class 3 trails according to United States Forest Service trail classifications and built according to hiking parameters. For Class 3 hiker/pedestrian trails in non-wilderness single-lane configurations, the design parameters specify a tread width of 18 to 36 inches, a target grade of 3 to 12 percent with a short pitch maximum of 25 percent, and a design turn radius of 3 to 6 feet, among other specifications detailed in the file.
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S u s ta in a b le T ra il B rid g e D e s ig n
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 es-tablished 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
10/16/2008 s ta in a b le T ra il B rid g e D e s ig n
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.
s ta in a b le T ra il B rid g e D e s ig n
Trail Design Parameters 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 es-tablished 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
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:
Bridges with handrails: 84 clear width
Other than bridges: 36
Bridges without handrails:
Bridges with handrails: 84 clear width
Other than bridges: 36
Bridges without handrails:
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 s ta in a b le T ra il B rid g e D e s ig n
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 other factors contributing to surface stability and overall sustainability of the trail.
s ta in a b le T ra il B rid g e D e s ig n
Trail Design Parameters 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 es-tablished 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 s ta in a b le T ra il B rid g e D e s ig n
Designed Use
BICYCLE Trail Class 1 Trail Class 2 Trail Class 3 Trail Class 4 Trail Class 5
Design
Cross
Slope
Target
Cross Slope
5% – 10% 5% – 8% 3% – 8% 3% – 5% 2% – 3%
Maximum
Cross Slope
10% 10% 8% 5% 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 other factors contributing to surface stability and overall sustainability of the trail.
s ta in a b le T ra il B rid g e D e s ig n
Trail Design Parameters 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 es-tablished 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)
May be common or placed for increased challenge
Common and left for increased challenge
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 s ta in a b le T ra il B rid g e D e s ig n
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 other factors contributing to surface stability and overall sustainability of the trail.
s ta in a b le T ra il B rid g e D e s ig n
Trail Design Parameters 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 estab-lished based on trail-specific conditions, topography, or other factors, provided that the deviations are consistent with the general intent of the appli-cable 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)
May be common or placed for increased challenge
May be common and left for increased challenge
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 s ta in a b le T ra il B rid g e D e s ig n
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 )
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 other factors contributing to surface stability and overall sustainability of the trail.
s ta in a b le T ra il B rid g e D e s ig n
Trail Design Parameters 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)
May be common or placed for increased challenge
Common and left for increased challenge
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 s ta in a b le T ra il B rid g e D e s ig n
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 other factors contributing to surface stability and overall sustainability of the trail.
s ta in a b le T ra il B rid g e D e s ig n
Trail Design Parameters 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 es-tablished 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)
Uncommon
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% s ta in a b le T ra il B rid g e D e s ig n
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 other factors contributing to surface stability and overall sustainability of the trail.
s ta in a b le T ra il B rid g e D e s ig n
Trail Design Parameters 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 estab-lished based on trail-specific conditions, topography, or other factors, provided that the deviations are consistent with the general intent of the appli-cable 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)
Uncommon
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% s ta in a b le T ra il B rid g e D e s ig n
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 allowed Width 48
Some light vegetation may encroach into clearing area
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 other factors contributing to surface stability and overall sustainability of the trail.
s ta in a b le T ra il B rid g e D e s ig n
Trail Design Parameters 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 es-tablished 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)
Uncommon
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 s ta in a b le T ra il B rid g e D e s ig n
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 poten-tial, and other factors contributing to surface stability and overall sustainability of the trail.
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