f. Step 6: Convert the answer into meters. Multiply 17 times .75. This will get an answer of 12.75
meters. Round it off to the next highest 13 meters.
g. This formula will work on the inner portion of the road or on the outer portion of the road.
18. Slope Percent Formula.
a. The speed at which a vehicle can travel is affected by the slope of the ground. Military vehicles
have limited capabilities on slopes. The Army determined that a slope percent of 7 percent or greater
obstructs traffic flow. The Army has developed a formula to determine slope percent. The formula is:
(1) Vertical over horizontal distance times 100 slope percentage. The method used is known as
line, sight, and pace method. Horizontal distance is the distance from the bottom of the hill to the top of
the hill. Vertical distance is from the base of the slope (or hill) to the top of the hill. (see Appendix A.)
(2) Use the average line of sight height of a soldier (1.75 meters) to get the vertical distance in
this formula. To determine the horizontal distance, use the normal pace of 30 inches (or .75 meters).
(3) Stand at the base of a slope facing towards that slope. Take a pencil or other object with a
straight edge to sight with. Have your partner walk up the slope, counting the paces as he goes. Hold
the pencil horizontally in front of your eyes. Sight down the pencil until you see the heel of his boot. At
this point, tell your partner to stop. Walk up the hill to where your partner is. Count the paces. Once
you reach your partner, tell your partner to continue walking. Count his paces again. When you see
his heel again or he reaches the top of the slope, tell him to stop. You have obtained the vertical
distance. Remember that the average person's height is 1.75 meters. The person walked up the hill
two times. Multiply the number of times the individual walked up the hill times 1.75. In this case it will
be 2. Multiply 2 times 1.75 which becomes 3.50 meters. This will be the vertical distance.
(4) Now go back to the horizontal distance. Suppose the distance was 75 paces plus 125
paces. Add those two together for 200 paces. Remember we had to convert paces to meters. Our
vertical distance is already in meters (3.50). We now have to convert horizontal distance from paces to
meters. 200 times 1.75 gives us 150 meters.
(5) Use the information just obtained. Insert in the formula
Use 3.5 for vertical and 150 for the horizontal. Divide 150 into 3.5 to equal .0233. Multiply that by 100.
You will get an answer of 2.33 percent.
MP1007
3-16
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