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Chapter 4 Working with Cross Sections
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5 Specify the volume computation type, Prismoidal or Avgendarea:
n
Average End Area Calculation: For the average end method, the
calculations for volumes takes the area of cut or fill at one station plus the
area of the cut or fill at the next station divided by two, multiplied by the
distance between the stations. The commands calculate all data from the
actual values, but the reported values are rounded to the volume precision of
your choice.
n
Prismoidal Calculation: The prismoidal method of calculating volumes is
more accurate than the average end area method. However, this technique
involves a more complicated calculation and may take a longer time to
process.
The prismoidal method calculation is:
Total sum of cut (or fill) area at first station (A1), cut (or fill) area at second
station (A2) plus the square root value of A1*A2. Divide the total sum by 3
and multiply by the distance between the two sections.
The following prompt is displayed:
Use of curve correction (Yes/No) <Yes>:
6 Specify whether to use curve correction:
n
Type Y to use curve correction.
n
Type N to skip this option.
In normal volume calculations, the length between the end areas on horizontal
curves is taken from the length along the centerline curve. With curve
correction in use, the length is taken from the path of the average centroid of
the areas for a more accurate result.
The following prompt is displayed:
Use of volume adjustment factors (Yes/No) <Yes>:
7 Specify whether to use volume adjustment factors:
n
Type Y to use volume adjustment factors. You are then prompted for the cut
and fill adjustment factors.
n
Type N to skip this option
NOTE
For a material that expands 15 percent, enter the value
1.15
. For a material
that shrinks to 93 percent of its original value, enter the value
0.93
. A
factor of 1.00 does not adjust the volumes.
The following prompt is displayed:
Output file name <alignment.txt>:
8 Specify an output file name. Include the path and extension when entering the
file name. The default filename and path are set by the Output Settings
command.
9 Specify the range of stations to use. Enter the beginning and ending stations in
the range.
The command displays the surfaces being calculated as it generates the existing
ground surface volume report. If several surfaces are being calculated, then the
volumes of each surface are reported separately.