stations 11 + 00 and 11 + 43 have been plotted.
The field party took, for each station, the ground
elevation 40 ft to both the right and to the left
of the center line. For each station, however, the
center-line distance of the intermediate elevations
varies. Therefore, these are irregular sections.
For both of the stations plotted, the HI was
76.70 ft. For the point 6 ft left of the center line
at station 11 + 00, note the 4.2 written below the
6. This reading was obtained from a rod held on
this point. The number 72.5 shown in the
parentheses right below the number 4.2 is the
elevation of this point. You obtain the elevation
by subtracting from the HI, the rod reading FS:
76.70 – 4.20, or 72.50
You can see this point is plotted 6 ft to the left
of the center line and at an elevation of 72.5 ft
in figure 14-29, view B. Now if the notes are
reduced in the office, the general practice is to
print the elevations in RED; then the elevation
just computed (72.5) will appear in red in the
cross-section notes (fig. 14-29, view A).
After the road gradients, either preliminary
or final, have been designed, plot the design data
cross section on the existing ground line section
plot at each station to complete the picture of the
end-area as it will be in the finished highway.
Obtain the finished grade elevation for each
station from the profile. Plot the finished grade
point usually located on the center at each cross
section. Then draw in the outline of the pavement
surface, ditches, and cut or fill slopes as they show
on the typical design section. Plotting may be
done with triangles, but a faster method is to use
templates made of plastic, thin wood, sturdy
cardboard, or other suitable material. Prepare
templates for a cut section, a fill section, and
a sidehill section that may be flipped over to
accommodate the direction of hillside slope.
The procedures just described are the most
common and pertain to irregular sections.
However, if regular sections have been taken in
the field after the gradients have been designed,
then both the existing and the finished surfaces
will be plotted. Field notes for simplified three-
level sections on a highway are shown in figure
14-30. On the data side, the profile elevation and
the grade elevation at each station are listed. In
the columns headed Left and Right on the
Figure 14-30.-Field notes for three-level cross sections.
14-33
