If the engineer’s level is used, three crew members
are generally employed for fieldwork; they are the
instrumentman, the rodman, and one person to
hold the zero end of the tape at the center line.
When a hand level is used, two persons can take
care of the job—the instrumentman also holds the
zero end of the tape and is positioned at the
center-line station as the rod reading is taken. The
procedure followed is a trial and error process.
Under field conditions, the rodman is at times as
much as 200 or 300 ft away from the instrument-
man. If power equipment is operating nearby or
a wind is blowing, oral instructions cannot be
given to the rodman about where to take trials
shots; in fact, often there. is not a clear view of
the ground slope at the station being worked.
Consequently, the rodman must know as
much as the instrumentman does about the theory
and practice of setting slope stakes. The speed and
efficiency of the party depend on the rodman
more than on any other member. The rodman
must be constantly mentally alert.
The most practical field procedure requires
that the rodman know the value of W/2 and of
s (the slope ratio). This is not difficult, since these
values are usually constant for several stations,
and the rodman can be informed when they
change. A typical procedure for setting slope
stakes is as follows:
1. The instrumentman computes the center-
line cut or fill, using the HI, finished grade, and
the existing ground elevation. Refer back to figure
14-36.
2. The instrumentman calls or signals the
center-line cut or fill to the rodman.
3. The rodman mentally computes the
approximate value of d by multiplying h x s and
adding W/2. He pulls the tape taut while holding
the tape at the computed distances.
4. Noting the approximate rise or fall of the
ground, the rodman adjusts the approximate
value of d, moves to the d point, and sets up the
rod for a trial shot.
5. The instrumentman quickly calculates the
cut or fill at this point and calls the value to the
rodman.
6. The rodman compares this with the
estimated cut or fill. He should be fairly close and
should know at once whether to move toward,
or away from, the center line. Having a much
shorter distance over which to estimate ground
slope, he again estimates new cut or fill and
hs + W/2, and moves the rod to the new
d value.
Figure 14-38.-Setting slope stakes.
7. The instrumentman again gives the cut or
fill; if the value checks, the rodman calls or signals
back the cut or fill and the distance.
8. The instrumentman quickly checks the two
values mentally, and if the values are correct,
records the values in the field book, signaling
“Good” to the rodman.
9. The rodman marks and drives the stake.
With practice and on fairly smooth ground,
a good rodman will seldom miss the first trial by
more than 0.2 ft vertically and will, quite often,
hit the correct value on the first trial.
Figure 14-38 shows the application of these
procedures to an actual situation. The following
data are known for this slope-stake stakeout:
1. The station is 15 + 00.
2. The W/2 (from the typical design section)
is 20 ft.
3. The slope ratio is 1:1; therefore, s = 1.
4. The existing ground elevation at the center
line (from the previously run profile) is 364.00 ft.
5. The HI is determined to be 369.30 ft at that
setup.
14-39
