C - Specifications - Design_parameters.doc
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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 intent1. 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%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 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% |
| 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’ |
For definitions of Design Parameter attributes (e.g., 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 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.
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 intent1. 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 accepted |
| 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 accepted
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
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, limited grading May be frequently 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
Protrusions
≤ 6”
May be common and continuous ≤ 3”
May be common, not continuous ≤ 3”
Obstacles
12”
| 6” |
| 3” |
Designed Use
PACK AND SADDLE
| Trail Class 1 |
| Trail Class 2 |
| Trail Class 3 |
| Trail Class 4 |
| Trail Class 5 |
| Design Grade 2 |
| Target Grade |
5% – 20%
| 3% – 12% |
| 2% – 10% |
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”
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’ |
For definitions of Design Parameter attributes (e.g., Design Tread Width and Short Pitch Maximum) see FSH 2309.18, section 05.
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.
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 intent1. 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
| 18” |
| 18” |
| 36” |
| 48” |
| 60” |
| Design Surface2 |
| Type |
| Native, un-graded |
May be continuously rough Sections of soft or unstable tread on grades < 5% may be common and continuous
Native, limited grading
Sections of soft or unstable tread on grades < 5% may be common
Native with some onsite borrow or imported material where needed for stabilization, occasional grading Intermittently rough Sections of soft or unstable tread on grades < 5% may be present, but not common Native, routine grading with improved sections of borrow or imported materials Stable with 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”
No protrusions
Obstacles
24”
| 12” |
| 10” |
| 8” |
| No obstacles |
| Design Grade 2 |
| Target Grade |
| 5% – 20% |
| 5% – 12% |
| 3% – 10% |
| 2% – 8% |
| 2% – 5% |
Short Pitch Maximum
30%
50% on downhill-only segments 25%
35% on downhill-only segments
| 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 |
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”
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’ |
For definitions of Design Parameter attributes (e.g., Design Tread Width and Short Pitch Maximum) see FSH 2309.18, section 05.
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.
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 intent1. 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 accepted |
| 8” – 24” |
| 18” – 36” |
| 24” – 48” |
| Typically not designed or actively managed for motorcycles, although use may be accepted |
Double Lane
48”
| 48 ” – 60” |
| 60” – 72” |
Structures
| 36” |
| 48” |
| 48” |
| Design Surface2 |
| Type |
Native, limited grading
Native with some onsite borrow or imported material where needed for stabilization, occasional grading Intermittently rough Sections of soft or unstable tread on grades < 5% may be present Native with imported materials for tread stabilization common, routine grading
Sections of soft tread not common
Protrusions
≤ 6”
May be common and continuous ≤ 3”
May be common, not continuous ≤ 3”
Obstacles
18”
May be common or placed for increased challenge 12”
Common, left for increased challenge
3”
Uncommon
Design
Grade 2 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 |
Designed Use
MOTORCYCLE
| 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% – 5% |
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”
48” – 60”
60” - 72”
Shoulder Clearance
6” – 12”
| 12” – 18” |
| 12” – 24” |
| Design Turn |
| Radius |
3’ – 4’
| 4’ – 6’ |
| 5’ – 8’ |
For definitions of Design Parameter attributes (e.g., Design Tread Width and Short Pitch Maximum) see FSH 2309.18, section 05.
The determination of trail-specific grades, 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 trail sustainability.
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 intent1. 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 accepted |
| 48” – 60” |
| 60” |
| 60” – 72” |
| Typically not designed or actively managed for ATVs, although use may be accepted |
Double Lane
96”
| 96” – 108” |
| 96” – 120” |
Structures
| 60” |
| 60” |
| 60” |
| Design Surface2 |
| Type |
Native, limited grading
Native with some onsite borrow or imported material where needed for stabilization, occasional grading Intermittently rough Sections of soft or unstable tread on grades < 5% may be present Native with imported materials for tread stabilization common, routine grading
Protrusions
≤ 6”
May be common and continuous ≤ 3”
May be common, not continuous ≤ 3”
Obstacles
12”
May be common or placed for increased challenge 6”
May be common, left for increased challenge 3”
Design
Grade 2 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
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
5% – 10%
| 3% – 8% |
| 3% – 5% |
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”
60” – 72”
72” - 96”
Shoulder Clearance
0” – 6”
| 6” – 12” |
| 12” – 18” |
| Design Turn |
| Radius |
| 6’ – 8’ |
| 8’ – 10’ |
| 8’ – 12’ |
For definitions of Design Parameter attributes (e.g., Design Tread Width and Short Pitch Maximum) see FSH 2309.18, section 05.
The determination of trail-specific grades, 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.
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 intent1. 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 accepted |
| 72” – 84” |
| 72” – 96” |
| 96” – 120” |
| Typically not designed or actively managed for 4WD Vehicles > 50”, although use may be accepted |
Double Lane
16’
| 16’ |
| 16’ |
Structures
| 96” |
| 96” |
| 96” |
| Design Surface2 |
| Type |
Native, 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, occasional grading Intermittently rough Sections of soft or unstable tread on grades < 5% may be present Native with imported materials for tread stabilization common, routine grading
Protrusions
≤ 12”
May be common and continuous ≤ 8”
May be common and continuous ≤ 4”
May be common and continuous
Obstacles
36”
May be common or placed for increased challenge 24”
Common, left for increased challenge 12”
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 |
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
8% – 15%
| 5% – 12% |
| 5% – 8% |
Maximum Cross Slope
15%
| 12% |
| 8% |
| Design Clearing |
| Height |
6’ – 8’
| 6’ – 8’ |
| 8’ – 10’ |
Width
72” – 84”
72” – 96”
96” - 144”
Shoulder Clearance
0” – 6”
| 6” – 12” |
| 12” – 18” |
| Design Turn |
| Radius |
| 10’ – 15’ |
| 15’ – 20’ |
| 20’ – 30’ |
For definitions of Design Parameter attributes (e.g., Design Tread Width and Short Pitch Maximum) see FSH 2309.18, section 05.
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.
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 intent1. 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 Groomed Width |
| Single Lane |
| Typically not designed or actively managed for cross-country skiing |
| 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
Double Lane
6’ – 8’
| 8’ – 12’ |
| 12’ – 16’ |
Structures
| 36” |
| 36” |
| 36” |
| Design Grooming and 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
12”
8”
(no obstacles if machine groomed) No obstacles
| Design Grade 2 |
| 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% |
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)
6’ – 8’
8’
(or height of grooming machinery) 8’ – 10’
Width
24” – 60”
Light vegetation may encroach into clearing area 72” – 20”’ 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’
For definitions of Design Parameter attributes (e.g., Design Tread Width and Short Pitch Maximum) see FSH 2309.18, section 05.
The determination of trail-specific grades, 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.
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 intent1. 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 snowmobiles. |
| 36” |
| 36” – 48” |
| 36’ – 60’ |
| Typically not designed or actively managed for snowmobiles. |
Double Lane
60”
| 72” |
| 72” – 96” |
Structures
| 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
12”
Uncommon 8”
Uncommon
No obstacles
| Design Grade 2 |
| 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% |
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)
| 6’ – 8’ |
| 8’ |
| 8’ – 10’ |
Width
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’
(provide sufficient radius for grooming equipment)
For definitions of Design Parameter attributes (e.g., Design Tread Width and Short Pitch Maximum) see FSH 2309.18, section 05.
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.
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 intent1. 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. |
| 4’ – 6’ |
Typically not groomed
6’ – 8’ (or width of grooming equipment) On tight-radius turns, increase groomed width to ≥ 10’ 8’ – 10’ (or minimum width of grooming equipment) On tight-radius turns, increase groomed width to ≥ 12’ Typically not designed or actively managed for snowmobiles.
Double Lane
10’
Typically not groomed 10’ – 12’
12’ – 20’
Structures
| 6’ |
| 12’ |
| 18’ |
| Design Surface1 |
| 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
12”
6”
No obstacles
| Design Grade 2 |
| 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 |
Designed Use
SNOWMOBILE
| Trail Class 1 |
| Trail Class 2 |
| Trail Class 3 |
| Trail Class 4 |
| Trail Class 5 |
| Design Cross Slope |
| Target Cross Slope |
0% – 10%
| 0% – 5% |
| 0% |
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’
For definitions of Design Parameter attributes (e.g., Design Tread Width and Short Pitch Maximum) see FSH 2309.18.
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.
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File details come from the government source that posted it. Updated .