B = time per cubic yard picking, loading, and wheeling any given kind of
earth to any given distance when the wheeler loads his own barrow.
[Transcriber's note -- formula and Tables omitted]
This general formula for barrow work can be simplified by choosing
average values for the constants, and substituting numerals for the
letters now representing them. Substituting the average values from the
note sheet on Fig. 2 (page 151), our formula becomes:
[Transcriber's note -- formula omitted]
In classes of work where the percentage of rest varies with the
different elements of an operation it is most convenient to correct all
of the elementary times by the proper percentages before combining them.
Sometimes after having constructed a general formula, it may be solved
by setting down the substitute numerical values in a vertical column for
direct addition.
Table 3 (page 164) gives the times for throwing earth to different
distances and different heights. It will be seen that for each special
material the time for filling shovel remains the same regardless of the
distance to which it is thrown. Each kind of material requires a
different time for filling the shovel. The time throwing one shovelful,
on the other hand, varies with the length of throw, but for any given
distance it is the same for all of the earths. If the earth is of such a
nature that it sticks to the shovel, this relation does not hold. For
the elements of shoveling we have therefore:
s = time filling shovel and straightening up ready to throw.
t = time throwing one shovelful.
w = time walking one foot with loaded shovel.
w1 = time returning one foot with empty shovel.