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.