Question

Why is it necessary for the estimator to visit the site even when extensive site information is provided in the bid documents?

Answer 1

After reviewing various preliminary drawings, specifications and information the estimator visits the site of the proposed project. The estimator gathers information on access to the site; surface topography and drainage, and the availability of electricity, water, and other services. The estimator records this information, which may go in the final project estimate.

After the site visit, the estimator determines the quantity of materials and the labor required to complete the firm’s part of the project. This process, called the quantity survey or “takeoff,” involves completing standard estimating forms, filling in dimensions, numbers of units, and other information. A cost estimator working for a general contractor, for example, estimates the costs of all of the items that the contractor must provide. Although subcontractors estimate their costs as part of their own bidding process, the general contractor's cost estimator often analyzes bids made by subcontractors. Also during the takeoff process, the estimator must make decisions concerning equipment needs, the sequence of operations, the size of the crew required, and physical constraints at the site. Allowances for wasted materials, inclement weather, shipping delays, and other factors that may increase costs also must be incorporated in the estimate.

After completing the quantity surveys, the estimator prepares a cost summary for the entire project, which includes the costs of labor, equipment, materials, subcontractors, overhead, taxes, insurance, markup, and any additional costs that may affect the project. The chief estimator then prepares the bid proposal for submission to the owner. On large construction projects, there may be several estimators, each specializing in one area, such as electrical work or excavation, concrete, and forms.

Construction cost estimators also may be employed by the project's architect, engineering firm, or owner to help establish a budget, manage and control project costs, and to track actual costs relative to bid specifications as the project develops. During construction, estimators may be employed to manage the cost of change orders and negotiate and settle and extra costs or mitigate potential claims. Estimators may also be called upon as expert witness on cost in a construction dispute case.

In manufacturing, cost estimators usually are assigned to the engineering, cost, or pricing department. The estimator's goal is to accurately estimate the costs associated with developing and producing products. The job may begin when management requests an estimate of the costs associated with a major redesign of an existing product or the development of a new product or production process. For example, when estimating the cost of manufacturing a new product, the estimator works with engineers, first reviewing blueprints or conceptual drawings to determine the machining operations, tools, gauges, and materials that will be required. The estimator then prepares a parts list and determines whether it would be more efficient to produce or to purchase the parts. To do this, the estimator asks for price information from potential suppliers. The next step is to determine the cost of manufacturing each component of the product. Some high-technology products require a considerable amount of computer programming during the design phase. The cost of software development is one of the fastest growing and most difficult activities to estimate. As a result, some cost estimators now specialize in estimating only computer software development and related costs.

Thereafter, the cost estimator prepares time-phase charts and learning curves. Time-phase charts indicate the time required for tool design and fabrication, tool “debugging”—finding and correcting all problems—manufacturing of parts, assembly, and testing. Learning curves graphically represent the rate at which the performance of workers producing parts for the new product improves with practice. These curves are commonly called “cost reduction” curves, because many problems—such as engineering changes, rework, shortages of parts, and lack of operator skills—diminish as the number of units produced increases, resulting in lower unit costs.

Using all of this information, the estimator then calculates the standard labor hours necessary to produce a specified number of units. Standard labor hours are then converted to dollar values, to which are added factors for waste, overhead, and profit to yield the unit cost in dollars. The estimator compares the cost of purchasing parts with the firm's estimated cost of manufacturing them to determine which is less expensive.

Computers play a vital role in cost estimation because the process often involves complex mathematical calculations and requires advanced mathematical techniques. For example, to undertake a parametric analysis (a process used to estimate costs per unit based on square footage or other specific requirements of a project), cost estimators use a computer database containing information on the costs and conditions of many other similar projects.