GLOSSARY
 
Common Trail Terms Climbing Turn  A rounded, usually insloping turn designed and constructed to allow users a flowing, easily-navigable turn.  Climbing turns have been replacing switchbacks in many areas. Mechanized trail building equipment allows the installation of climbing turns on steeper cross-slopes. The turn itself is generally easier to maintain, as its rounded shaped reduces user-caused abrasion and erosion. Crusher Fines This term is often applied to many different types of gravel or road base mixes. Generally, the term is used to describe gravel/fines mixes especially suitable for trail use. The ideal mix will be highly compactible, with the right mix of angular rock and fines so that even when wet, it drains well and is not muddy. Culvert  A method of channelling water underneath a trail, usually with galvanized steel or plastic pipe.  Generally, a catch basin is created above the trail, the culvert is then buried underneath the trail between the catch basin and the downhill side.  Usually a rock lining is lain on the downhill side to slow the flow of water, and rock headwalls are built at the inlet and outlet. Grade  A measurement of trail angle, generally described in terms of percent.  Percent is determined by a formula of rise over run, or the amount the trail rises (or drops) in feet over a length of 100'.  For example, if a trail rises at a grade of 10%, that would mean it has climbed 10' over a length of 100'.  In practical terms, a grade of 5% or less would generally be considered a "beginner" trail, whereas one of 10% or more would generally be considered "advanced." Grade Reversal A point where the grade of a flat contoured, climbing, or descending trail is reversed, or the grade changed to the opposite direction. The length, depth, and height of each grade reversal will vary depending on a variety of factors. Grade reversals are usually designed into a new trail, and built at the first phase of construction. They are generally considered the best and most sustainable method for shedding water off a trail. Along with an offsloping tread, regular grade reversals are a reliable, low-maintenance method to assure good trail function. Offslope   The angle to which the tread, or trail surface, slopes toward the downhill side.  Trails with a greater offslope angle will shed water faster and help avoid erosion.  Too little offslope angle will result in puddling of water, or running of water down the trail surface. Too much offslope angle, however, makes a trail uncomfortable for foot traffic, and can lead to tread creep. Road Base  A type of soft trail surface.  As the term suggests, this material is commonly used underneath asphalt on paved roads and trails.  Road base is a mixture of sand, clay and gravel, with the particular mix varying depending on its use.  For trails, this material can be compacted into a fairly hard surface, yet it remains soft enough to be comfortable for horses and trail runners.  The material is usually light brown, and has a natural look.   Rolling Dip   A drop in the trail grade to shed water.  Rolling dips generally replace water bars as the control measure of choice, since they require less maintenance and can handle more water.  Rolling dips can be constructed by hand or by mechanized means.  The SWECO dozer is especially adept at creating highly effective dips which are virtually unnoticeable to trail users. Using grade reversal and rolling dip technology, there is usually NO reason to ever install a traditional waterbar.   SWECO Trail Dozer  SWECO is the name of a manufacturer.  It builds the 450 and 480 trail dozers, which are engineered and built specifically for trail construction.  These are state-of-the-art machines, capable of a wide range of construction in variable conditions.  The dozers are 4' wide by about 11' long and 6' high.  They weigh about 9,000 pounds, are powered by turbodiesel engines, and have hydraulic controls with full hydrostatic drive.  The 6-way floating blade and rock rippers allow the user to remove most rock and roots from the trail, leaving a smooth and sustainable finished surface.  Alpine Trails uses the latest edition, the 480 dozer, for most of its construction projects. This piece of equipment allows us to provide the most efficient, cost-effective natural surface trail construction.   Switchbacks  A tight turn on a steep sideslope.  In most instances swithbacks are being replaced by climbing turns.  However, climbing turns (which more closely follow the natural contours of the hill) may not be practical on steep slopes.  In those cases, a switchback, which is a tighter turn incorporating a flat turning platform with mild-grade entrances and exits, will be built.  Switchbacks create specific side support and drainage problems which must be addressed for the turn to function properly. Tread   The trail surface itself, or the area which is "tread" upon by the trail user. Tread Creep A condition where the tread tends to slide, erode, or otherwise slip downhill or outside of the desired alignment. Creep can be caused by various means, but most often happens when users are forced out of the preferred alignment to avoid puddles or obstacles, or when the offslope angle is too steep for conditions. copyright © 2001-2009 Alpine Trails, Inc.