1.1. Construction Background The construction of complex structures is a major undertaking. In the public sector, project viability and public support for future projects are partly based on the success of past projects. And in the private sector, large complex structures can be financially rewarding or devastating for both the builder and the owner. More complex projects share the common theme that they involve risks and uncertainties that can cause increased costs. For example, approximately 80% of all projects begin the construction process with a high level of uncertainty. The construction project manager has challenging tasks to build a complex project that stays within budget. The main objective of this research is to present a methodology that helps project managers control costs during the construction of a complex structure. Project management is the application of knowledge, skills, tools and techniques to project activities in order to meet or exceed stakeholder needs and expectations from a project (PMI 1997). These expectations revolve around the scope, schedule, cost and quality of the project. Project management functions consist of: scope, cost, time, human resources, communications, quality, contract/procurement, risk, and project integration (PMI 1997). This thesis focuses on the cost control aspect of project management. Project managers in the civil engineering and shipbuilding professions have long recognized the need for improvements in the area of ​​cost control, and cost management includes estimating, scheduling, accumulating and analyzing cost data and finally, implementation measures to correct a cost problem. Current cost control techniques tend to focus on changes in line items once the document is the focus of their profiles.1.5.1.1. Cost Control and Cost Accounting Cost control should not be confused with cost accounting. Cost accounting involves recording cash receipts and related disbursements, accounts payable, accounts receivable, inventories and initial investments, as well as maintaining other general and subsidiary accounts. Cost accounting identifies, defines, measures and reports the various direct and indirect cost elements associated with the production of goods and services. The main objective of cost accounting is to communicate financial information to management for planning, control and evaluation. Therefore, cost accounting is one of the primary means to an end. This research will not focus on the internal workings of any cost accounting system, but will instead focus on controlling costs using data provided by sound cost accounting techniques.