It is seldom that the original bid estimate to perform a particular construction activity is the same as the actual cost to do the work. The estimate will always be higher or lower because of any number of unforeseeable factors that will cause the variation. It is essential, therefore, if a contractor is to make a profit, for the contractor and the project manager to keep current on a project's cost by maintaining a reliable and accurate cost control system. what is the most effective approach to control construction cost? As a project manager, what procedures will you use, in collaboration with the contractor, to track construction activities and costs?