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Measuring construction project performance is an important piece of the project management/project controls process and must be taken very seriously. The industry has historically used measures of change from the original contract's time and cost as its cardinal performance metrics [8]. While these metrics certainly are well-- used and well understood, they suffer from a lack of clarity as to what they actually portray with respect to project performance. The change in a project's time and cost are typically called time growth and cost growth [9, 10]. They are generally represented as either a positive or negative percentage of original contract requirements. While these are indeed useful measures, they do not numerically indicate the reason for the change from original nor do they assign responsibility for that change. For example, a project with a high level of construction cost growth could be suffering from a very poor original design that necessitated the issuance of costly change orders. This is not the fault of the construction contractor. Conventional wisdom would rule that the project is "going sour" and generally ascribe responsibility to the constructor [3]. On the other hand, the same cost growth could be the function of a costly unforeseen site condition or act of God over which neither party to the contract has control.
On the other hand, a negative value of both time and cost growth is generally seen as beneficial, and the project is usually ruled "successful" [3]. For instance, if an owner decides to remove a feature of work from the original contract, both time and cost growth will become negative because the owner has reduced the scope of work from the original. However, by building less than originally contracted, the project performance metrics will both be negative and the project will be thought to have finished "ahead of schedule" (negative time growth) and "under budget" (negative cost growth).
The other issue with the use of project performance metrics is their individual applicability for the type of construction that they are measuring. Construction projects can generally be categorized into vertical construction (architectural and other building-type projects) and horizontal construction (highways, railroads, bridges, etc.) [10]. The two types have different contractual bases. Vertical projects tend to have a firm-fixed price contract...