When preparing the final construction project estimate, the compilation of which we described in previous chapters, the scope attributes for each category of design entity-elements are either collected manually or extracted from the volume attribute specifications provided by CAD (BIM) programs.
In the traditional manual process that has existed for the last ten thousand years, the foreman and estimator perform a detailed analysis of drawings presented in the form of lines on paper or in PDF (PLT) or DWG formats. Relying on their professional experience, foreman and estimator accurately calculate the attributes of the volumes of work and materials required. This method requires considerable effort and time, as well as special attention to detail. Determining the scope attribute in this way can take anywhere from a few days to a few months, depending on the scope of the project. In addition, because each measurement and calculation are done manually, there is a risk of human error, which can lead to inaccurate data, which then affects errors in project time and cost estimates for which the entire company will be held responsible.
In modern practice, the use of CAD (BIM) design models greatly facilitates the process of calculating volume attributes. This is achieved by the ability to automatically calculate volume for a group of entity elements when the geometry of each entity group is represented in CAD (BIM) as detailed tables with volume attributes. When a CAD (BIM) model of the project is available, the estimating department contacts CAD (BIM) specialists to export the volume and quantity attributes in tabular form.
If the requirements of the estimating department were taken into account when developing the 3D CAD model, and the names and identifiers of the element entity groups match the identifiers of the estimating groups, the volume attribute data from the CAD systems can be automatically entered into the estimating systems.
Automatic acquisition of volumetric attributes in the form of specifications from CAD (BIM) models allows you to instantly get up-to-date data on the cost of works and total project cost, while ensuring high accuracy and efficiency of calculations.
Tables with volume attributes from CAD (BIM) are automatically entered into the estimate, and summing all the values automatically gives the total cost of the project
Automatic obtaining of quantities from CAD (BIM) projects with using specifications and tables created in CAD (BIM) program is performed using QTO (Quantity Take-Off) tools by grouping all project entities by special element identifiers or element attribute parameters.
