distance equal to incline distance, reasonable accuracy may be obtained only for slopes less
than 30 percent.
180
193 (B)
160
140
120
100 (A)
1,000 m
5,000 m
0m
2,000 m
3,000 m
4,000 m
Find Vd:
Spot elevation B
=
193 m
Spot elevation A
=
100 m
Vd
=
93 m
Find Hd:
Road distance from A to B
=
3,720 m
Calculate the percent of slope:
Vd
93
x 100 = +2.5% = ♂ 3%
x 100 =
Hd
3,720
Figure 1-3. Map Method to Determine the Percent of Slope
1-2. Curves. Curves are another land feature that must be considered by reconnaissance
personnel as possible obstructions to traffic. The speed at which vehicles can move along a
specified route is affected by curves.
a.
For reconnaissance purposes, curves with a radius of curvature of 25 meters and
less are considered obstructions to traffic flow and are indicated by the abbreviation OB in
the route classification formula. Curves with a radius of curvature between 25.1 and
45 meters are reportable on an overlay but are not considered obstructions.
EN 5622
1-4
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