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EST.01
Anyone who has been performing estimating for a period of time knows that the productivity varies at different job sites and even on the same job site at different times. Predicting productivity is often one of the more difficult tasks confronted by an estimator. The purpose of this paper is threefold. First, productivity will be defined so that we can all communicate effectively. Second, we will discuss the factors that affect construction productivity. Third, we will discuss how you can determine the basis of your estimate database for productivity application. Finally, a productivity application spreadsheet will be presented for developing the factor to apply to your estimate.
WHAT IS 1.0?
There are two things to ask regarding a productivity of 1.0. First, you must decide what the productivity basis is for the unit hours in your database. This will be discussed in a later section of the paper. Second, the more important question may be, "Is 1.3 better or worse than normal productivity?" In order to understand the application of productivity it is important to define the productivity factor. For this paper it is assumed that productivity will be defined as units of input per units of output. As an example, let us assume that it normally takes 6 hours to install a composite cubic yard of concrete. Therefore, below normal performance would require more than 6 hours per cubic yard. We will assume that the factor is a multiplier and therefore a factor larger than 1.0 reflects below normal productivity.
Base project estimate for composite concrete = 6.0 hours per cubic yard
The inverse to the productivity factor is the production factor. Production is defined as the units of output per period of time. If we use the above example and assume a crew of 8 men:
While the above description of productivity and production factors is relatively basic, it is not unusual that companies and software arc inconsistent with this definition. They use a factor of less than 1.0 for a poor productivity factor and greater than 1.0 for a poor production factor. It is not important which definition you use for the factors except that all parties using the factor must understand the use. So for this presentation and...