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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."
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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. |
| 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.
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| 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.
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SWECO 450 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 8,000 to 10,000 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.
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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.
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| Tread The trail
surface itself, or the area which is "tread" upon by the trail
user.
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