The goal of Building Information Modeling (BIM) is to achieve collaboration and coordination in the implementation of design and various other elements of any construction project. Whenever designs from different disciplines are joined together on a common platform, many hard and soft clashes and workflow clashes occur. BIM efficiently helps contractors and construction engineers in detecting these clashes, by considering constructability or operations of the building.
The question is, why is clash detection so important in BIM? To answer this question, first it is important to understand what exactly a clash is. A clash occurs when variables of different models occupy the common space. Clashes maybe geometric, like pipes passing through walls. Schedule based clashes occur when various sequential aspects of work are scheduled to occur simultaneously or in reverse order, or clashes may occur when changes and updates are not made to the drawings.
Clash detection aids in effectively identifying, inspecting and reporting interference in a construction project model. It is useful in checking work status and wanes down human errors during model inspections. Clash detection is important in BIM because it integrates several models (structural, MEP, etc.) into a single BIM model. With clash detection feature, faults that conventionally were detected on the site and involved high cost and schedule implications, if corrected at that stage, can now be seen by BIM service providers in the office even before visiting the site. With BIM, clash detection is made possible for even objects within objects (like a steel rod completely immersed inside a concrete wall).
In case of huge buildings, manual clash detection and resolutions take a lot of time and still may not give a satisfactory solution. On the other hand, with BIM, clash detection can be done easily and with utmost accuracy. That is the reason why clash detection is so important in BIM.