Cost engineers in industry use a very simple model based on factors of man-hours of labor per unit of production. The factors are based on experience. The use of predetermined time and motion studies requires a finished engineering design and a methods study.
e = man-hours per unit of the process, p, being performed, in Earth environment
F = factor by which e will be increased or decreased
for the process, as a function of location
p = manufacturing, extracting, or erecting process being evaluated
W= quantity of the end product in production units
I = location at which the process will be carried out
= man-hours required to produce W units of production by the process, p
E = man-hours required for some finished structure or unit.
Then for any process and any location,
and for any finished structure or unit,
The model makes possible a labor estimate at any stage of design, simply becoming more detailed as to operations and factors as the design becomes more firm.
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