This paper was first published in the Canadian Journal of Civil Engineering, Vol. 21, 1994 pp 939-953, under the title "A Pragmatic Approach to Using Resource Loading, Production and Learning Curves on Construction Projects". It has been modified only to the extent necessary to make it presentable in web page format. Published here October, 2001.

## Appendix 1

Definitions and Formulae adopted in this paper

#### Production (Rate)

The rate at which units are produced over a given period of time, independent of the number of man-hours consumed.

#### Productivity

In its broadest form, productivity may be described as a measure of how well the resources in a firm are brought together and used to accomplish a set of results.[7] In its simplest form, it may be expressed as the ratio of output to input or the actual rate of output or production per unit of time worked.[8] These represent measures of production efficiency. When measurements are taken over a given period of time, the period productive efficiency is the number of units produced in that time period divided by the number of man-hours to do so.

#### S-curve

When the cumulative total of on-going work on a construction job is plotted against time, the resulting curve typically follows the shape of the letter "S". It is more generally referred to as a Progress Curve.

#### Learning or Experience Curves

Studies have shown that the change in cost associated with a change in productivity has, in many situations, a characteristic curve that can be estimated with reasonable accuracy. This is called the "learning curve" or "experience curve".[9]

The underlying phenomenon is that skill and productivity in performing tasks improve with experience and practice and there are a number of different ways of plotting this relationship that facilitate mathematical analysis. Two models of Learning Curves are given in Appendix 2, Learning Curve Mathematics.

#### Well-run

A well-run construction job implies that adequate and realistic planning has taken place and a positive cultural environment has been established for the performance of the work on site. It also means that supporting logistics, including delivery of materials and equipment, have been properly assessed and will be provided when needed to enable optimized crew sizes to maximize their production at least cost at each point in time. It follows that the resulting project should be perceived as successful in terms of meeting requirements and being completed within credible time and cost parameters. For an owner this would mean that the resulting facility has satisfied the stipulated needs, within reasonable time and budget. For a contractor, it would mean satisfying the owner at a profit.

In contrast, actual progress on a not-so-well-run job will depart from the plan or proceed as "a voyage of discovery". The records will likely reflect wasted manpower before sufficient work is available or after it is substantially completed, lower productivity, higher manpower turnover, additional learning costs, added supervision, labour and non-labour-related job expenses and overhead, added material storage, handling and wastage, and extended completion.

Standard Resource Input curve (SRI S-curve)

Points on the SRI S-curve may be determined as follows:

Standard Production Output curve (SPO S-curve)

Points on the SPO S-curve may be determined as follows:

7. Cleland, D. I. 1990. Project Management Strategic Design and Implementation. TAB Books Inc. Blue Ridge Summit, Pennsylvania. 344.
8. Cleland, D. I. and Kerzner H. 1985. A Project Management dictionary of Terms. Van Nostrand Reinhold C. New York. 193.
9. Anthony, R. N. and Reece, J. S. 1975. Management Accounting: Text and Cases.Richard D. Irwin, Inc., Homewood, Illinois. 540.