Coordination and Clash Detection
BIM requires collaboration between designers. The coordination of the single models into the federated (combined) model requires close collaboration. Clash detection and the subsequent clash resolution is a key component in producing a buildable design.
Each clash that is resolved during the design process eliminates the possibility of a clash staying undetected until it becomes an on-site re-work event that will have cost and potentially time implications. Undetected clashes resolved on-site may also result in unsatisfactory and uncoordinated solutions.
A clash within a model occurs when a modelled geometric element or component occupies the same space as another element or component. For example a steel through the location of an internal door.
Each individual design organisation will be responsible for ensuring that their model is free of clashes. For example components of the architectural model should not clash with any other architectural components. A WIP model should not be issued as a shared model until such clashes have been resolved (refer to the requirements of the Common Data Environment for more detail).
The lead designer, usually the architect will produce the primary model. Other designers models should be coordinated to ensure that they do not clash with the lead designer’s model and also with the other designers.
It is usual that not all clashes can be resolved in isolation. Such clashes should be collated (and tracked) and resolved through a collaborative approach. A good method to resolve clashes is to have a clash detection and coordination workshop with the whole design team in attendance where the federated model and the clashes can be viewed. To get the maximum benefit a clear list of clashes that require resolution should be established in advance of the workshop.
The tolerance and the method for identifying clashes should be established within the EIR/BEP. Rules within clash detection can be setup to allow for a tolerance between elements, such as an allowance for a minimum distance between elements or an allowance for an acceptable overlap. The rules and allowances for clashes should mean that when a model is checked for clashes the same clashes can be reported by all stakeholders.
Clash Detection Tools
Tools that can be used to undertaken clash detection and coordination are listed here.
Tekla BIMsight should receive a special mention as it is a very capable model viewing tool with the ability to undertake clash detection and best of it is free, so readily available for use throughout the supply chain.
Ultimately, the coordination and clash detection tools that you choose should be the right tool for the project and should be agreed between the main stakeholders.