23.23 Exhibit 01 Design Parameters for four-wheel drive vehicles.pdf
PDF 194 KB Posted
- Attached to
- Sand Route Improvements and Restoration
- Solicitation number
- 1240BE26Q0048
- Issued by
-
Department of Agriculture Forest Service
About this file
This document is a technical guidance exhibit establishing design parameters for four-wheel drive vehicle trails greater than 50 inches in width on National Forest System lands. The guidance provides standardized technical specifications for survey, design, construction, maintenance, and assessment of trails based on Designed Use and Trail Class designations, with allowances for local deviations based on trail-specific conditions and topography.
The parameters are organized across five trail classes with specifications for design tread width (single lane ranging from 72" to 120" depending on class), double lane width (16 feet across classes 2-4), and structure minimum width (96 inches). Design surface requirements progress from native materials with limited grading in Trail Class 2 to native materials with imported stabilization materials and routine grading in Trail Class 4. Additional specifications address allowable protrusions (ranging from 12 inches to 4 inches maximum) and obstacle heights (from 36 inches in Trail Class 2 to 12 inches in Trail Class 4). Trail Classes 1 and 5 are typically not designed or actively managed for vehicles greater than 50 inches in width, though use may be permitted. This guidance document is non-binding and intended to provide clarity regarding existing requirements and agency policies.
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2309.18_20
The contents of this guidance document do not have the force and effect of law and are not meant to bind the public in any way. This document is intended only to provide clarity to the public regarding existing requirements under the law or agency policies.
23.23 – Exhibit 01
DESIGN PARAMETERS FOR FOUR-WHEEL DRIVE VEHICLES
GREATER THAN 50 INCHES IN WIDTH
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 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
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