Five Essential Principles
1. The Half Rule
The trail’s slope should be less than half the slope of the land on either side. This prevents water runoff that causes erosion and safety hazards, even on gentle terrain.
2. Ten Percent Average Guideline
The overall average grade of the trail should be 10% or less, balancing erosion control and user experience across varying soil types.
3. Maximum Sustainable Trail Grade
Certain sections may exceed 10% depending on soil composition, sideslope, rainfall, user type, and usage frequency. Professional designers determine safe maximum grades for each situation.
4. Grade Reversals
Integrate periodic sections (every 20-50 feet) where the incline levels or dips briefly to funnel water off the trail. These also serve as natural resting points for users.
5. Outslope
The outer (downhill) edge of the trail should have a 3-5% outward slope, channeling water away from the path surface.
Benefits
- Environmental Protection: Minimizes erosion and preserves ecosystems
- User Safety & Experience: Manages water flow and improves navigation
- Aesthetic Appeal: Creates visually pleasing, naturally integrated trails
- Durability & Maintenance: Reduces repairs and long-term costs