Rethink Clash Detection ? Standardise and Automate

Photo: Clash due to clearance issue

Photo courtesy: Autodesk Knowledge Network

Buildings are getting more complex to meet the rising market demands, maximise use of available land and enhance occupant comfort. These results in multiple levels of services packed closely together to function in a seamless manner above an aesthetically designed false ceiling. Ensuring smooth execution and maintenance of these services requires fully coordinated drawings where all prospective clashes among services are resolved upfront. The process to come up with such drawings requires better integration of information, effective communication and smarter use of technology. As per MGI survey , there is a common consensus among owners, contractors and design consultants that the design and planning processes need improvement and require technologically advanced softwares. The main driving force behind this is that the cost of identification of clashes at an early design stage is negligible compared to the exorbitant cost of rectification and correction later during execution or maintenance.

Though the advantages of clash detections are well known in the industry, 3D generation softwares such as Autodesk Revit, MicroStation, Vectorworks Architect, ArchiCAD generate a clash report only between models of different disciplines. Though it serves the purpose to a certain extent, it does not apply any logic beyond identifying straightforward clashes. At the same time, it also flags elements which are actually built-in by design. For example, the fire hydrate in mechanical model could be touching the wall in architecture model, and is a required connect. But the software will identify it as a clash. Due to such a limitation, the BIM manager usually has to spend substantial time to review the clash report manually in order to identify valid findings and assign the tasks. It is an iterative process of identification, communication and rectificationand has to be run a few times for a fully co-ordinated model.

The next generation softwares such as Navisworks and Solibri, 3D Repo not only identify clashes but rather help in addressing the constructibility issues by carrying out advance clash detection, deficiency detection such as egress analysis and matching design (architecture v structure).

This enables the BIM manager to set rules for maintaining safe tolerance among different services within the model. With simple rules, BIM manager can set the minimum distance from a duct to be 900 mm (3 ft) or space around the MEP pipes to be 150 mm.

Similar checks can also be performed by respective disciplines at a frequent interval for quality checks. By setting the rules, architects can define the door clearance, width of staircases and other standard parameters for quality check.