Building Trails

In early 2012, I attended a Trail Building class at Devil's Den State Park that was put on by the International Mountain Biking Association with support from Friends of Devil's Den State Park.  They went over lots of tips on building and maintaining sustainable trails in ways that minimize erosion, maximize fun, and minimize long-term maintenance costs and needs. I've included some of the things I learned below, but if you are passionate about trail building, you should check out IMBA's resource page,  get their book on Trail Solutions, or convince your local parks department or nearby state park to apply host an IMBA Trail Care Crew event.

1.  Keep water and water flow in mind at all times when designing and building trails.  Place trails along contours when possible and keep slopes to a minimum.

My rough notes are below and I will convert them into a more organized format when time allows.

Manage water impacts.
 Avoid fall lines. Fall lines are steepest route of decent down a slope. No fix for trail on fall line.
Trails are compacted soil and no vegetation, obviously need to avoid water flow. Build trails on contour. Keeps users on trail, keeps water off.
Singletrack - skinny trail. Close to nature. Smaller footprint. 12-36 inch wide Less trail to maintain. Minimizes user conflict
Clinometer , tells you slope in the field while building trails.
 Half-rule : trail tread grade should be less than half the slope of side slope. Keeps water from diverting down the tread.
 Example: side slope is 16%, trail grade should be less than 8%. maximum grade shouldn't exceed 15% even if slope is greater If steeper, use rock or built structures.
Or armored sections. Average grade guidelines: keep average grade less than 8%. outslope - slope across trail tread. Slope gently away from high side of trail. Sheet flow, off trail ASAP. 5% Grade reversals.

 Create watersheds along trail. Make sure trail switches from up to down at least every 100-200ft.

 Know your trail users: hikers, horse riders, trail runners, bikers.
 Hikers are destination oriented and mobile, able to leave trail.
Trail runners are distance oriented and into trail experience, trail flow.
Equestrians , need more clearance, reinforced tread, no stairs, access to water.
 Beginner trail tread should be under 5% most of the time. Very smooth trail, short loops available. 2-4 miles.
Intermediate mtn bike trail - connecting loops, rougher tread, steeper grades.

 Planning a new trail. Get out map. Identify control points. Locate sensitive or important areas. Locate desired destinations. Overlooks, water, natural features, historic sites.
Mark where you shouldn't have a trail. "social trails" trails made by users, not planned Incorporate more dangerous natural features farther out on the trail.
Avoid low lying and environmentally sensitive areas.
 Trails increase property values, more traffic and eyes in an area.

 Trail flow- open and flowing: good sightlines, long sweeping corners, faster speeds Tight and technical - slower, twisting tight turns
 Problems where flow changes abruptly. Blend flow with flow transitions.
Corral rocks and log chokes, add turns, slow people down. Add uphill slope where leaving faster straight trail and entering curvy slower trail.
 Trail system design.
Stacked loop trail system. Located parking near main road. Picnic tables, easy trails, kiosks, bathrooms at trailhead. Short horse only entry spur can decrease horse waste on shared trail sections. Core loop, good sightlines, wider trail, easy paths near trailhead. 1-2 mile loops
Middle loops, hybrid. Narrower trail, steeper grades, rougher trail. Label intersections with easy trail so people don't get in trouble. 10 mi.
Outer technical loops, tight and technical, longer climbs, rougher trails.

 Design and build a trail- Get idea of good location meeting rules above. Rough flag route with flagging around trees. Check side slope regularly. Follow that half rule. Have experts survey route for sensitive sites ecological or historical. Then put in pin flags, where actual tread will go. On downhill side of trail. These are closer than tree flagging. Test the flow by running or walking the trail. Define and clear corridor. Wide enough and high enough for your users. Clear small trees and limbs from larger trees. Under cut large branches before cutting on top. Also remove weight of branch before final cut near trunk. Dig small tree stumps out of ground if in the middle of the trail. Avoid leaving spears along side of trail.
 1. Rake organic material to uphill side of trail.
2. Mark where uphill edge of tread will be.
3. Cut down to mineral soil. More stable than organics. Broadcast debris on down hill side.
4. Blend cut back into hillside. Prevent erosion, make traveling near hillside more inviting.
5. Out slope the trail tread. 5%. Mc cloud Compact back slope and tread.. Finish the tread, use raked material to cover exposed slopes and dirt. Remove flags. if you do a partial bench tread, using wall cut material, use a retaining wall.

 Climbing turns on 10-15% or less, built on existing grade. Build grade reversal before and after to get rid of water coming down the part on fall slope. 30ft diameter. insloped turns.

15-25% side slope. Grade reversals before and after turn. Turn is banked, and armored with retaining wall. downhill end wide and smooth to dump water. Switchback turn. Steep side slopes. Tight turn is level. Lots of work and material to build well. top of turn is insloped. Grade reversal before and after turn. Armoring. Fortify wet areas. Harden soft tread.

Add challenge. Use rock sling/spider to carry rocks. Stone pitching- lots of small rocks buried. First excavate stretch of trail, put large anchor stone at beginning of armored section. Add small rocks behind, tightly arranged, lots of rock on rock contact. Work sand or fines into cracks. Most of rock should be under surrounding ground area. Flagstone paving, with larger flatter rocks. Still use anchor stones, just don't have to be quite as far underground.
 Water crossing - cross at narrowest straightest point. Go higher in drainage. Install grade reversals before and after crossing to keep water in stream bed. For small creeks and seeps can use large flat stones on streambed. Features for added difficulty. Skinny, ramp,constructions Optional lines Maintenance Keep corridor clean Maintain sheet flow, reestablish out slope. Water bars don't really work. High maintenance need.
 Use nicks, an increased out slope, where puddling occurs. Rolling grade dip - built grade reversal. Do reroutes and closures on fall line sections, steep grades, bad flow, poor drainage sites. Choose appealing re-route. Revegetate quickly. Use topsoil and transplants from reroute construction. Vertical dead fall , stick cut limbs, dead trees in ground to break sight lines. Cover with leaves, and grass.

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