Collision detection refers to the process of examining building components, structural elements, mechanical equipment, and plumbing and electrical lines within a building model using BIM software to identify any intersections or clashes. After detecting collisions, the design team makes adjustments accordingly and keeps detailed records. Collisions can be categorized by mode into hard or soft collisions, and by type into either single-discipline or multi-discipline collision detection.
1. Collision Detection Using Revit
Revit allows collision detection on BIM models created through collaborative design. Its built-in clash detection tool can precisely identify collision points by generating conflict reports and displaying them visually. Users can directly modify the position of conflicting pipelines within the model. However, running the clash detection feature requires a high-performance computer. Conventional computers may experience slow processing times due to hardware limitations. To improve efficiency, zone-based detection is recommended to limit the number of components analyzed.
Here’s how to perform collision detection in Revit:
1. Use the “Insert” tab on the ribbon and select “Link Revit” to import models from other disciplines into the current project for integration. Then run a collision check on the combined model to identify any clashes between selected components.
2. To reduce computing load, not all elements need to be checked against each other. For example, pipelines don’t need to be checked against doors, windows, or furniture. Note that Revit can detect clashes between components within the current project and linked models, but it cannot detect collisions solely between two linked models. Therefore, achieving “zero clashes” requires multiple checks involving both the current model and linked models.
After detection, Revit automatically lists all conflicting components and generates a clash report. If no clashes are found, the software will display a “no conflict detected” message. Clicking any conflict in the report and selecting “Display” will highlight the collision location and involved components for easy identification and correction. Designers can export and save the report in HTML format. Once all issues are resolved, refreshing the report will remove the resolved conflicts.
2. Collision Detection Using Navisworks
While Revit demands high hardware specs for clash detection, Navisworks offers a more accessible solution with lower hardware requirements. Most standard computers can run Navisworks efficiently. Its user-friendly interface allows designers to quickly learn and operate the software. However, Navisworks serves only as a clash checking tool and does not support direct model modifications. Identified clashes must be referenced back to Revit for corrections.
The main steps for collision detection in Navisworks are:
1. Attach Files: Export each discipline’s model from Revit in the NWC format and load these files into Navisworks for integration.
2. Set Collision Parameters: In the Clash Detective module, select the objects to be checked and specify the type of collision—hard, soft, or gap collision. Soft collisions require defining allowable crossing tolerances. You can also create custom ignore rules to tailor the detection process for your project, enhancing efficiency. Run the clash detection to generate a report.
3. Analyze Collision Reports: After the check, Navisworks produces an XML-formatted report detailing collision points, project IDs, status, images, and grid locations. This information enables the design team to quickly locate clashes. Using project IDs, they can return to Revit to find and correct the conflicting elements in the original model.
These are the primary BIM software tools suitable for collision detection. I hope this overview proves useful for your projects!
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