a.
The clinometer method is the easiest to perform. A clinometer is an instrument
that directly measures the percent of slope. There are several variations in the Army
inventory. This instrument is organic equipment for most engineer units.
b.
When a clinometer is not available, use the percent-of-slope formula as shown in
Figure 1-2 along with the map or the pace method to find the correct values for the vertical
and horizontal distance. The vertical distance (Vd) and the horizontal distance (Hd) must
always be expressed in the same unit of measure.
B
Vd = 100 m
Slope
90
Vd
A
Percent of slope =
x 100
Hd
Hd = 1,000 m
100 m
Percent of slope from A to B =
x 100 = +10%
1000 m
,
Figure 1-2. Percent-of-Slope Formula
(1) A large-scale map (1:25,000) may be used to approximate the percent of
slope. After the slope has been identified on the map, the difference in elevations between
the top and bottom of the slope is found by reading the elevation contours or spot elevation.
Then the horizontal distance is measured. Both of these values must be in the same unit of
measure. The values obtained for horizontal and vertical distances are then substituted in
the percent-of-slope formula and the percent of slope is computed. This method is not
suitable where a cut or a fill has been used to reduce the gradient of the route. Figure 1-3,
page 1-4, shows an example of using a large-scale map to determine the percent of slope on
a route.
(2) The pace method relies on a soldier's line of sight to measure the vertical
distance and pacing off the ground to measure the horizontal distance (Figure 1-4,
page 1-5). The average eye level is 1.75 meters above the ground. The average pace is
0.75 meter. These measurements should be accurately determined for each member of a
reconnaissance team.
(a) With his head and eyes level, a soldier stands at the bottom of the
slope. The soldier then sights a spot on the slope. This spot should be easily identified. If it
is not, another member of the team may be sent forward to mark the location. The
individual making the sighting then walks forward to the marked spot and records the
number of paces. This procedure is repeated until the top of the slope is reached. The
vertical distance is then computed by multiplying the number of sightings times the eye-
level height. The horizontal distance is computed by multiplying the number of paces times
the soldier's measured pace or 0.75 meter.
(b) The percent of slope can then be calculated by substituting the
values into the percent-of-slope formula. Because this method considers horizontal
1-3
EN 5622
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