Clash detection has a high return on investment in the design and construction process. A considerable amount of time and money will be saved if collisions in design models are registered and fixed early on. We’ll look at clash detection, why it is essential, and how to do it efficiently with BIM technology.
Small things can have a significant impact in both a positive and negative way. For example, you can imagine the consequences if not every designer notices a structural designer’s systematic 100-millimeter increase in the concrete beams’ height of a building. In the worst-case scenario, the unnoticed change causes costly on-site rework, which already takes up 28% of project time (How We Build Now Report, 2023, by Censuswide).
In the days of 2D drawings, it took a lot of scrutiny to detect potential clashes between designs. Overlaying drawings on a light box was a typical procedure. With three-dimensional BIM and models, we should have a better chance of identifying and avoiding conflicts. After all, designers can combine each other’s models and immediately see if an MEP designer’s pipe goes through a beam or if an architect’s door does not have a corresponding opening in the load-bearing wall.
However, the reality is not as perfect as it appears. That’s why we need tools for BIM clash detection. They aim to ensure a model’s building components have the correct quantities, dimensions, and positions.
Detection of hard and soft clashes
The clear-cut way to think about clash detection concerns checking the geometrical properties of a model or a combination of models, a so-called federated model. A model can have internal clashes or conflicts with other models.
A clash happens when two building components occupy the same space. They can be objects within objects or intersecting objects. These are called “hard clashes.” Duplicate parts fall into this category as well.
The other category of clashes is “soft.” They occur when a component is placed within another component’s buffer zone. This could be a tolerance zone or, for example, a free service space required in front of an electrical cabinet.
Speeding up clash detection
Typical clashes occur between structural and HVACE or architectural model objects. The number of HVACE installations is constantly growing. For example, a newly built Finnish hospital’s BIM model contained around 40,000 structural objects, while it had 450,000 MEP objects. As a result, checking an HVAC against a structural model can initially have over a thousand clashes. Trying to go through that number manually is a daunting task. Even though some companies still rely on a fully manual model checking, the benefits of using specialized software for the job are overwhelming.
Solibri, the pioneering leader in model-checking software, allows designers, BIM managers, and BIM coordinators to audit individual and federated BIM models automatically. It offers default rules for checking model quality, and the users can customize or extend them to specific project needs or standards.
“I just asked them, hey, what are you guys doing right now? What are you doing today? I’m checking this and that. All right, so how long does that take for you? Well, it’s going to take me about a day. Okay, let me show you how to do it using Solibri, and it’ll take you about half an hour.”
An elemental part of BIM’s success
Why do BIM models have clashes in the first place?
There are many reasons, but the asynchronous design process is a fundamental issue. Due to pressing schedules and distributed responsibilities and contracts, working on the same federated model in real-time is still rare, though technically possible.
Deficient communication is another culprit. Trying to communicate model changes manually is laborious, and keeping up with them is demanding.
Every designer should do internal clash detection before sharing their models. That would radically reduce the number of clashes in the federated model.
As BIM is becoming the backbone of all building-related information management, minimizing model-related errors programmatically is vital. Common Data Environments (CDEs) and BIM Communication Format, BCF, further enhance the checking process. Solibri’s integration offers an easy way to access and synchronize project files from CDEs, such as BIM360, Trimble Connect, Catenda Hub (Bimsync), and Aconex.
Going beyond clash detection
Clash detection is an essential function of Solibri, but it is just one part of the BIM quality assurance process. Model quality is also about design quality. This involves ensuring that the model is technically valid and that the design solution complies with the requirements.
Other aspects of model checking include:
- Code compliance – Verifying that the design adheres to relevant building codes and standards, including accessibility, fire safety, and environmental regulations.
- Accessibility analysis – Ensuring that the design complies with accessibility standards, like adequate space for wheelchair movement and proper placement of handrails.
- Project information compliance – Checking that the model complies with client and project-specific guidelines and requirements.
- Model comparison – Comparing different model versions to track changes over time.
- Custom checks – Allowing users to create custom rules to address specific project needs or company standards.
These checks are essential for improving the quality, safety, and efficiency of construction projects.
Clash detection tools are naturally necessary for designers, BIM managers, and BIM coordinators, but their value extends to the whole value chain.
Value for all project participants
Manufacturers and element producers can deliver the right products the first time, and on-site teams don’t have to improvise installations because of conflicting designs. The productivity of everyone in the project improves, providing better profitability in the low-profit-margin industry.
As a result of a systematic and quality-assured process, clients get a good product delivered on time and budget. This fosters trust and encourages clients to cooperate with the same partners in the coming projects.
This article was originally published on solibri.com.