Page 24 - Industrial Process Plant Construction Estimating and Man Hour Analysis

Introduction xxxix

Factors affecting labor productivity and impacts of overtime
The American Association of Cost Engineers defines productivity as a “relative
measure of labor efficiency, either good or bad, when compared with an estab-
lished base or norm.” Estimates are based on a defined work scope, duration, start
date and clarifications, and exceptions to the bid documents. The design may be
incomplete, or changes are made that will impact the bid estimate.
Examples of impacts that affect labor productivity are as follows:
Project has added work scope and owner request project completed on bid
date. Request may require increased craft manpower, a second shift, overtime,
and many other impacts to the schedule and estimate.
The increased man-hours, extended schedule, and other resources will
impact the schedule and project cost.
Delay of owner provided material and equipment to be install will affect the
erection sequence, duration, and schedule of work packages. Reassignment of
craft is required.
These impacts will cause an increase in manpower and joint occupancy with
other trades causing a drop in productivity.

Labor factors

The estimator can use the following table of labor factors and values for
factoring labor productivity for work packages.
The overtime labor factors provide a basis for estimating inefficiencies
utilizing quantitative data actually measured on construction projects.
The principles and techniques in this manual will enable the experienced
estimator to apply the methods to measure, analyze, and compile accurate
estimates for industrial projects (Tables 9–11).