Glossary of Terms

Back-cut - The vertical part of the bench cut that's blended into the backslope.

Backslope - Slope on the uphill side of the trail. This should be a gradual change from the tread, slowing runoff by preventing a waterfall effect.

Bench cut - A semi-flat trail tread created by digging down to mineral soil in the hillside. Care must be taken to preserve some outslope while making a ridable and walkable path.

Berm - The ridge that develops along the downhill edge of a trail. It's caused by tread compaction and soil displacement during trail use. A berm traps water on the trail.

Bridge - Allows trail users to pass over ravines, bogs, creeks, rivers and similar obstacles.

Climbing turn - A turn that transitions from one leg to the next as the trail ascends (or descends) a hill.

Clinometer - Instrument used to measure the slope of ground. Also known as an inclinometer or clino.

Contour trail - Pathway that gently traverses a hill or sideslope, following natural contour lines as illustrated by a topo map. Allows water to sheet across the trail, thus minimizing impact to the tread.

Control points - Places of interest that trail users will be attracted to (desirable) or should avoid (inappropriate). Mark control points and use them to determine the placement of a new trail.

Crib wall - A retaining wall that raises the trail significantly. Often used to stabilize the trail tread and prevent it from collapsing down the fall line. Can be built with rock or wood.

De-berming - Removing the berm, or ridge of dirt that forms along a trail's downhill edge. Restores the tread's outslope, allowing water to sheet off. (See "outslope" and "berm.")

Directional use trail - A trail intended for travel in one direction only. May be reversed periodically.

Drainage - Removal of water from the trail.

Erosion - The natural process of wearing down and moving rock and soil by wind and water. Trail erosion can be accelerated by a combination of users, water and gravity.

Fall line - Direction that water flows down a hill. The path of least resistance.

Fillslope - The portion of a trail that's constructed from excavated material. Fillslope can be unstable so should not be used to build trail tread. Full bench construction is preferred.

Flow - The rhythm or "feel" of a trail. Two basic types include "open and flowing" and "tight and technical."

Full bench - Tread construction method of excavating down and into the hillside. Puts the entire tread width on mineral soil, maximizing sustainability. (See "bench cut.")

Grade - Trail steepness. (See "percent of grade.")

Grade reversal - Brief change in trail grade direction, such as routing a downhill section back up the hillside for a short distance. Used to divert water off the trail.

Grade dip - Undulation in the tread that traps water and diverts it off the trail. Makes trails more interesting and fun to use.

Half rule (50 percent rule) - If the trail grade exceeds 50 percent of the hillside slope, gravity will pull water down the trail instead of across it. This is known as "exceeding the fall of the hill."

Hybrid - A trail design that blends "open and flowing" and "tight and technical" features.

IMBA - International Mountain Bicycling Association, P.O. Box 7578, Boulder, CO, USA 80306; (303) 545-9011; www.imba.com. Leading resource for mountain bike-oriented trail design, construction, maintenance and management information, and mountain biking in general.

Knick - Shaved-down section of trail, about 10 feet in diameter, with an exaggerated outslope. Like a rolling grade dip, a knick is used to shed water off a trail.

Land manager - Any person responsible for decisions regarding the use of public or private lands.

Mineral soil - Dirt that's below the top layer of leaves, roots and other organic material. When making a bench cut, always dig down to mineral soil if possible.

Multiple-use trails - Those used for more than one type of activity, such as for cycling, hiking and horseback riding.

Open and flowing - A trail design marked by sweeping turns, higher speeds and longer sight lines.

Outslope - Trail tread that's canted very slightly in the same direction as the hill's slope. Allows water to sheet across rather than be trapped.

Percent of grade - Preferred method of measuring slope or a hill's steepness. For example, a grade of 10 percent means there is a rise or fall of 10 vertical feet per 100 linear feet.

Re-route - A new section of trail that replaces an existing section. Re-routing is often the best remedy for a poorly designed trail that requires frequent maintenance.

Rolling grade dip - A non-obtrusive feature that diverts water off the trail by altering the grade. It's essentially a man-made grade reversal.

Sheet flow - A dispersed flow of water. It minimizes erosion by preventing water from achieving high velocity and carrying away topsoil.

Sill - Stone or timber supports that keep bridge stringers from contacting the ground.

Singletrack - A trail so narrow that users must generally travel in single file.

Single-use trails - Designed for only one type of user. This can be a problem if other users begin traveling the trail.

Slope - The natural (or man-made) pitch of the land, as shown on contour maps. Generally refers to the hill, not the trail. The trail "slope" is called "grade."

Social trails - Paths created by people who wander away from set trails.

Stringer - A structural component of a bridge. It spans from bank to bank and supports the decking.

Subaru - Great cars! Sponsor of the Subaru/IMBA Trail Care Crews. Ask for the heated seats.

Subaru/IMBA Trail Care Crews - IMBA's "Johnny Appleseed" program for spreading expert information about trail design, construction, maintenance and management.

Sustainable trails - What every designer and construction crew should strive for: low-maintenance trails that have minimal impact on natural systems.

Switchback - A sustainable turn on a hillside. The trail is routed onto a level deck where it makes a transition to the opposite direction.

Texturing - Placing natural features (rocks, logs, etc.) back into the tread to increase its technical nature. Helps limit speed, and thereby reduces user conflict.

Tight and technical - A trail design that includes tight turns, natural technical features and mandates slower speed.

Topographic (topo) map - Charts elevation changes and shows features such as knolls, ravines, rivers and contours.

Trail corridor - The area around and above the tread. Remove fast-growing impediments, but leave grasses and trees.

Tread - Ground on which trail users travel. It may include grass, bare dirt, roots or rocks. Tread width varies depending on the type of trail and its users.

Tread creep - Describes a contour trail sagging or sliding down the hill. Causes include bushes or trees protruding into the trail from above, exposure of roots from an uphill tree, an improper bench cut or poor trail flow.

Turnpike - Trailbuilding technique that uses a combination of gravel, soil or other filler material to make the tread higher than the surrounding water table. Useful in low-lying areas with poor drainage.

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