Civil and Environmental Engineering Questions

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Chapter 17
Problem 6
What is the cost breakdown structure (CBS)? What are its purposes? What is included (or excluded)? How does it relate to a work breakdown structure (WBS)?

Cost Breakdown Structure (CBS) A hierarchical decomposition of project costs, either on the basis of the organization of the project's work (its WBS) or the physical structure of the system (PBS), where each element in the decomposition contains the allocated budget (as a percentage of its parent in the hierarchy), any actual costs (for upward aggregation of project spend), the confidence in the cost (a percentage), and the amount of possible variation. It utilizes over 40 cost equations and 20 cost throughput parameters to characterize the life-cycle cost of a system. The purpose of the CBS is that the user can select the cost elements that best fit the application being analyzed and the CBS that best fits the Program Office and contractual requirements. It is also used to distribute system costs into phased expenditure categories by fiscal year. This allows allocation of costs to units for comparison of alternative equipment or approaches, and further allows the evaluation of costs over the life cycle of the system, accounting for the present value of money, as appropriate. The detail required in the baseline structure will depend on the complexity of the system and the level of analysis that will be undertaken during system development. The details of the baseline will influence the types of tools that will be required for analysis of alternative systems and approaches.

Work Breakdown Structure is a hierarchical decomposition of the work to be performed by the people in a project that identifies phases, milestones, gates and activities (which are often represented in a project network, plan, program or Gantt chart). It identifies the cost areas to which project costs are charged as the project unfolds, such costs often being associated with a Cost Breakdown Structure.

P-7
How does the CBS relate to the functional analysis (if at all)?

Functional analysis is the process of translating system operational and support requirements into specific qualitative and quantitative design requirements. The process is iterative and accomplished through the development of models using functional flow diagrams, n-squared charts, behavior diagrams, and IDEF models. Functional analysis is used in the CBS, where CBS analyzes each function to determine the cost breakdown structure of the system.

p-8
Describe some of the more commonly used cost estimating methods. Under what conditions should they be applied? Provide some examples.

Some cost estimating methods used in environmental, safety, and health (EHS) management are program cost estimating and trades estimating.
Program costs are done by ensuring that all ESH costs are included in the estimate, and reflecting the ESH costs consistent within the format requirements for Program cost estimates. Ensuring that costs are included can be accomplished by using a series of documents as checklists that stimulate research and questioning. This in turn, will lead to areas where ESH costs may exist. For example, during the Engineering and Manufacturing Development (EMD) phase of a satellite program, the prime contractor develops an alternate manufacturing process for satellite sensors to eliminate the use of several Class II Ozone Depleting Substances (ODS). The process applies to more than one component and more than one payload. The costs could be collected and accounted for under "Industrial Facilities, Equipment Acquisition or Modernization".
Trade estimating focuses on the delta costs between alternatives. Because over 80% of the ESH costs of alternatives take place, it is important that cost trades be LCC trades. Trade studies are really micro program cost estimates for two or more alternatives in which cost categories that have no change in value between alternatives, can be treated as infrastructure or ignored. Accordingly, the same approach that is used for the program cost estimate can be used for trade studies with several differences. The first difference is that after the list of ESH cost categories is prepared, each cost element is evaluated to determine whether it is sensitive to the alternatives. If it is, then it carries forward just as any cost identified for ...