In project execution, the impact of changes will be dependent on the period when the changes will be implemented. In concept definition or feasibility study, there might be a dozen of choices of achieving a single goal. But later on the project execution, these choices will be significantly reduced that selecting the most appropriate solution is deemed vital.
Small changes at this stage of the project will have a massive effect. A good example is changing a tag numbers to suit the correct area on the field.
The effect of this means that piping arrangement will change, cable routing will change, documents and drawings need to be changed. The few strokes on the keyboard to do the changes on the tag number can result in a pile of documents and drawings to be modified.
During a project construction, site personnel have initiated a change of location of electrical equipment. Unknowingly, despite moving the equipment only a few meters away from the original location, the plant area are not the same. As the equipment tag numbers are area dependent, then the electrical equipment tag numbers need to change.
This change was communicated to the design office. The effect of the site implemented change means that there will be about a thousand man-hours required in design compared to about two (2) hundred hours of site hours.
The result of the assessment prompted the construction engineer to revert back to the equipment original location.
A small change in the later stages of the project execution means a massive impact in cost and schedule.