(1) Formula.

All methods of determining percent of slope

involve the use of a formula.

The formula states that the vertical

distance, divided by the horizontal distance, times 100, equals the percent

of slope. You must be careful to always use the same unit of measurement

when using the formula.

(2) Map Method.

A large scale map may be used to approximate

the percent of slope. After the slope has been identified on the map, you

use the contour lines to determine the elevation at the bottom and top of

the slope.

The horizontal distance is determined by using the map scale.

These distances are then inserted in the percent of slope formula.

Be

careful to use the same unit of measurements. This is the least accurate of

the methods. It is helpful, however, when you have to do the route recon by

map, or when preparing for your recon. In the latter case, it helps you to

determine in advance where you may have to stop to calculate slope. This

method does not work where cuts or fills have been made to reduce the

gradient of the slope.

(3) Line of Sight and Pace. Line of sight and pace is a quick

method of estimating percent of slope. It is based on a soldier's line of

sight and pacing off to measure ground distance.

The eye level of the

average soldier is 1.75 meters (5 feet 7 inches) above the ground. The pace

of the average soldier is .75 meters (30 inches). These measurements should

be accurately determined for each member of the recon team.

With 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 identifiable. If not, another team member may be sent forward to

mark the spot. 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.

Fractions of an eye level height

must be estimated.

Vertical distance is then computed by multiplying the

number of eye level sightings by the eye level height. Horizontal distance

is computed by totaling the number of paces and converting it to meters,

based on the soldier's length of pace. For example, for the average soldier

it would be the number of paces times .75. These numbers are then used to

complete the formula.

g.

Road Widths.

Road widths, and how to determine them, were

discussed

on

page

1-31-1-32

in

the

section

dealing

with

route

classification. They include any constriction that reduces the traveled way

below the stated standards.

Such constrictions must be noted on the

overlay.

They include such things as narrow streets, drainage ditches,

embankments, and war damage.

The symbol for a road width constriction is

opposing triangles.

The points where the two triangles meet marks the

location of the constriction. The width of the constriction is placed at

the base of the left triangle. The length of the area that is constricted

is placed at the base of the one on the right. Both are in meters.

h.

Underpasses.

An underpass is depicted on overlays by a figure

which shows the structure's ceiling and is drawn over the route at its map

location. See Figure 1-20. The width meters is written to the left of the

symbol. The overhead clearance is written to the right of the symbol. All

measurements

MP1028

1-50

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