Among many BIM Uses listed on PennState, it is possible to highlight the ‘modeling of existing conditions’ as essential for planning and preparing a road project. And what does this term mean? It is the elaboration of a three-dimensional model with the mapping of the terrain where the project will be elaborated.
To capture this information in the field, there are the following options of methodology: traditional topographic survey, photogrammetry or laser scanner. The professional responsible for the project analyzes the most appropriate method for the case, evaluating the extension of the project, type of land, term, availability and cost-benefit.
Why is this surface so important? Because the mass balance is the first thing evaluated in a basic project, which is the total volume of excavation and compaction that this project has. Thereafter, it is important to understand if there is an equilibrium of the material, the need of donation/ purchase material or dump the material. Unfortunately, in the initial studies, the characteristics of the materials are not yet known because future geotechnical investigations will be necessary. However, in the project planning stage, mass balance information is essential. In addition, it should be noted that the earthmoving item has a significant impact on the total cost of the project.
Among the options of the methodologies mentioned, the aim of this text is to address the workflow of photogrammetry:
Step 1: request the authorizations from the competent agencies for the drone flight
Step 2: the drone is configured through the application that accompanies it in order to capture the terrain (flight plan).
Step 3: the flight is done and the photographs are captured
Step 4: These images are transferred to a computer
Step 5: With a specific software, these files are transformed into a mesh file or point cloud, where it is possible to manipulate, edit and better configure this data. The type of data will depend on the purpose of use.
Step 6: This file is imported into the highway modeling software, where it is possible to use it for the preparation of the basic study or project.
It is worth mentioning that these types of files resulting from photogrammetry are large, requiring good computers to perform this task, so, there is a significant investment for the adoption of such technology.
The idea here is not to promote one methodology over the other, as each case is different, and it may happen that a combination of technologies may be necessary to supply such demand. Because, sometimes not everything can be captured with a certain technology, so there is the need of a complementation from another technology.
Regardless of the chosen technology, the more accurate the region is mapped, the better the quality of the project because the result will be: a more economical, assertive project, with better productivity and less risk of rework. Technology is our allied force!
Image credits: Concessionária Rota das Bandeiras e Fernando Pellegrino Martin
Author: Solange Gaspar, Project Engineer | BIM | Road Infrastructure | Innovation. Alumni of the Zigurat’s Master Internacional em BIM Management para Infraestruturas, Engenharia Civil e GIS.