Change orders and construction projects characteristics: A relational quantitative study

The changes clause is recognized to be the most litigated in construction contracts because it affects, among other factors, the cost and the schedule of the project. This study examines the potential quantitative relationships that exist between the construction project characteristics and the impact of the change orders on the cost and on the duration of the project. The literature review provided a framework within which research variables were selected and research hypotheses defined. Data gathered on 104 publicly financed new projects have been statistically analyzed by the methods of multiple regression, using the computer SAS package.

The results of this study show that defective contract documents and differing site conditions are the two leading origins of change orders. Also, significant relationships were found between the type of the project and the impact of changes on both contractual cost and contractual duration. The same impact was found significantly related to the duration of the project.

The impact assessment of changes on project cost and schedule has motivated the modeling of regression equations to predict those changes on two types of projects included in the research sample. It was found that (1) the best predictors of the change in contractual cost of highway projects are the contractual cost and duration, the length of the road, the number of subcontractors, and the year in which the contract was awarded; (2) the change in highway project duration is best predicted by considering the geographical location of the project, its contractual duration, and the year in which it was awarded; (3) the change in contract cost of building projects depends on the year in which the project was awarded and the season in which its completion was started; (4) the best predictors of change in contractual duration of building projects were the project contractual cost and duration, and the year in which the contract was awarded.

Information generated from this study may be used by owners and contractors to reduce changes on the project, as well as to plan the project cost and duration with greater accuracy.