BIM or Building Information Modeling amalgamates different types of construction drawings. The final drawing is useful for architects, contractors, builders, and engineers. Clash detection is one of the many benefits of using BIM in the AEC industry. It provides valuable information during the design coordination stage where all the building systems are collaborated with the base models. During this process, we receive information about possible clashes between these designs, and these clashes can be categorized in various categories according to their characteristics. In this article, we will touch upon these different types of clashes and their detection techniques.
As per the National BIM Report 2019:
- 60% of the industry professionals say that BIM is cost-efficient along with speeding up the construction drawing process.
- The majority of the clients today are asking for BIM integrated models.
Since BIM involves a cumulative integration of design models, any disorientation among them leads to a clash. Clash detection has become easier with the help of BIM. With BIM, clash detection can be effectively done prior to the beginning of the construction process.
BIM clashes are further categorized in various categories. Let’s have a little tour.
Types of Clashes in BIM and Their Detection
Earlier the process for identifying design clashes was complex and needed hard labor. The architects would make the drawings on a tracing paper. Earlier, by aligning them on top of each other, they were able to find the clashes.
Modern clash detection software is able to filter out the collisions, clashes, overlaps, and other such anomalies in the construction model. Listed below are the types of clashes you would usually come across during the coordination process.
1. Hard Clashes
Hard clashes are easier to detect, but if they go missing, it becomes a costly affair.
A hard clash persists when two components of a building share the same space.
A duct that crosses through the pipes or electrical wires or a pipe that is crossing through a steel beam are examples of a hard clash. Such sort of incompatibilities in the design of the building is evidence of a hard clash. Irrespective of the type of clash, they inhibit the construction process and lead to an increase in time and total costs.
Also, out of all the types of clashes in BIM, hard clashes are most prominent.
Here’s something interesting: The Association of Construction Development has found that any type of clash if converted into monetary terms is kept at $17,000. A large building project has an average of 2000 to 3000 clashes. This brings the total cost to $34,000,000.
2. Soft Clashes
After a hard clash, soft clashes are the other types of clashes in BIM. Building construction is a precise and complex process. The designers have to address all kinds of spatial boundaries, tolerances, and buffers.
The spatial differences will help in maintenance and safety. Plus, it helps with accessibility and insulation works. Soft clashes arise out of the failure to account for this buffer zone.
Especially for the MEP drawings, the buffer zones maintenance is essential. An Air conditioning unit pipes needing buffer space for maintenance or alteration purposes is important. Failure to leave that much space is what accounts for a Soft Clash.
There are grave risks and problems associated with soft clashes. A wire that is very close to the plumbing water pipe, tantamount to short circuits.
3. Workflow (4D) Clashes
4D clashes are the last types of clashes in BIM. Also called Workflow clashes, these are timeline conflicts. They represent mismatch in the scheduling and delivery of the materials. Other than this, any interdisciplinary disputes arising out of the work methods of the stakeholders and the participants also amount to workflow clashes.
More importantly, the 4D clashes have a domino effect. A dispute in one segment leads to inhibiting the workflow in all the other segments.
With 4D BIM, all the timelines are set and readable by the contractors and other participants of the project. This creates a sync between the activities, and all of them can set their actions accordingly.
Coordination Meetings- Collaborative Process to Resolve All Types of Clashes
During the design coordination phase of building construction, Coordination meetings are a standard practice where general contractor lead and facilitate the coordination process. The individual building system designers are asked to produce LOD 300 design models to coordinate with base models, architectural and structural models. During the coordination meeting, the generated clash report is discussed and required design changes are decided to implement in the designs to avoid the clashes.
The coordination meetings are organized and design changes are made until the clash-free construction model is achieved.
From the Past to the Future of Clash Detection
From stacking the construction drawings on a light table to making 2D drawings to 3D modeling, Clash detection techniques have come a long way in identifying different types of clashes in BIM.
Light Table Technique
In the light table technique, the architect would stack the drawings one upon the other on the top of a light table. Then the AEC professionals would read the designs to find clashes in the structure.
Then came the 2D CAD technique for clash detection. It provided great tools that helped in carrying out the design with higher accuracy. The sketches and drawings became easier and faster to generate and share.
But with the help of 3D modeling, everything changed. Now the clash detection has become automatic. After the amalgamation of the designs in the BIM tools like Navisworks, the clashes are highlighted.
With the help of clash detection process, the design can be edited accordingly before the construction process begins.
Going ahead, the clash detection software is going to get even more sophisticated and precise.
- The Level 3 BIM is the first step into the future of making collaborative and coordinated construction designs.
With the help of BIM, it has become easier to understand the three types of clashes in BIM. Be it a hard clash, soft clash, or a workflow clash, the AEC professionals can have technically sound designs. Errors in the construction process can prove to be a costly affair. Keeping that in mind, the BIM software like Navisworks and Revit ensures consistent communication among all the components and segments of the building.