With the advent of Building Information Modeling (BIM) technology, digital representation of physical and functional properties of the building became possible. Still, despite all the technological advances, the coordination issue remains one of the major challenges of complicated construction projects. Therefore, the knowledge of BIM clash and clash detection is crucial.
Why BIM Clashes Matter?
First of all, it is vital to note that the appearance of coordination issues in any BIM projects is inevitable. The reason for such statements is that multiple disciplines, namely, architectural, structural, mechanical, electrical, and plumbing (MEP), develop separate models of the building which leads to overlaps, spacing problems, and scheduling conflicts.
Each team develops its model according to certain requirements and design needs. So, the architect develops the building envelope and the interior spaces; the structural engineer develops the load-bearing frame of the building; and finally, the MEP engineer develops the systems of the building. When these models converge, clashes arise as no discipline team knows what the others do.
Therefore, the early detection of clashes is critical in order to minimize the number of rework and to increase efficiency of the project. Detecting and solving the clashes in the design phase instead of the construction phase saves lots of money and time as the rework performed on the construction site is up to 10 times more expensive than in digital model.
What Are BIM Clashes?
By definition, BIM clash is the violation of clearance and tolerance rules and/or occupancy of the same physical space by multiple elements. In simple words, it is a digital signal telling "these two elements cannot be in one place at the same time".
However, clashes are not always limited to geometric intersection. They may also consist in accessibility, maintenance or sequencing issues. For instance, an element might fit geometrically, however, there is no enough space to perform the maintenance on it. Similarly, some materials might be scheduled for delivery in advance while the site is not ready to accept it.
Thus, the understanding of the BIM clashes as the coordination issues will help project teams to think more comprehensively about their work on the project.
Types of BIM Clashes
Hard Clashes
As the name suggests, hard clash is the collision or occupation of one physical space by several elements.
Common examples include:
A duct passing through a structural beam
A pipe penetrating a wall where no hole was预留
A conduit penetrating the structural reinforcement
HVAC equipment overlapping with structural column
This type of BIM clashes is easy to detect as there is always a geometric violation. However, they are also extremely expensive if not detected.
Discovering that there is a clash between major duct and a structural beam during the construction phase will require redesign, demolition and rework leading to delays of the whole project.
Soft Clashes
Soft clashes are clearance, buffer or access-space violations. There is no geometric intersection between these elements, however, they violate the clearance or access-space requirements.
Some examples are:
Insufficient maintenance space around mechanical equipment
Violation of safety clearance near electrical panels
Insufficient headroom in corridors and passageways
Fire sprinklers blocked by the other elements
Soft clashes are important in terms of functionality, safety and compliance. A building might be structurally strong and geometrical correct but if the maintenance personnel cannot access the equipment for maintenance it will fail in its functional purpose. Similar situation appears during the building inspection in case of safety code violation.
How Are BIM Clashes Detected
The process of BIM clash detection has a specific workflow.
Model Integration – At the first stage of the clash detection process, models are federated in one single coordinated model. All discipline models are imported into one common coordinate system.
Automated Clash Scanning – Special software scans the federated model for intersections, clearance violations and logic-based collisions. Rules and tolerances set by the project team are applied to detect potential issues.
Clash Identification and Categorization – At the next stage, clashes are identified and categorized according to the type of conflict (hard, soft or workflow), severity and location.
Clash Reporting – At the reporting stage, comprehensive report on detected clashes is generated. Every clash is described by the location, elements involved and potential solutions. Navigation links to elements are also included in the report.
Review and Coordination – At this stage, project stakeholders review the report and coordinate the solutions. Usually it consists of design changes and coordination meetings.
Rechecking After Fixes – At this final stage, the process of clash detection is run again to make sure that the issues were solved and there are no new clashes.
Manual vs Automated Clash Detection
Traditional manual detection consisted in comparing of 2D drawings from different disciplines visually. It was time consuming, prone to mistakes and limited in scope of analysis.
Modern automated clash detection in BIM software is a significant step forward. The automated tools can detect potential clashes scanning thousands of elements within several minutes while the manual detection would be hardly possible. Moreover, it provides more consistent results, minimizes human errors and allows focusing on the problem solving not searching for it.
In the case of complicated projects with hundreds of thousands of elements the use of automated clash detection is not optional – it is absolutely necessary.
Common BIM Clash Detection Tools
There are special software tools which are popular in clash detection workflow. Navisworks is one of the most famous platforms for the model aggregation and clash detection. Also Autodesk Design Collaboration and Forma, Solibri, Revizto and BIMcollab are popular.
These tools provide such services as model review, issue tracking and coordination among project stakeholders. The aim of this list is not comparison of tools' features but understanding that effective clash detection requires robust technology platform and clear process of work.
Why Clash Detection Services Are Important
The use of professional clash detection services is highly useful in order to catch the design issues as early as possible in the project life cycle. Such services provide special expertise and resources to the coordination process.
The business value of such services is obvious. It decreases the number of rework and thus reduces the costs of construction. The fewer requests for information (RFIs) will be, the fewer disruption will happen during the construction process. It also improves coordination and schedule control and makes project completion more predictable.
For those companies who lack in-house BIM coordination capability and for complicated projects with deadlines, professional clash detection services will be an efficient solution.
Benefits of BIM Clash Detection
There are multiple benefits of effective BIM clash detection process.
Reduced Rework and Change Orders – Fixing the problems in digital model is much cheaper than performing rework during the construction. Therefore, clash detection helps to avoid the change orders and rework.
Improved Coordination Between Teams – The clash detection process provides the opportunity to solve problems between the disciplines collaboratively and thus improve overall project coordination.
Accelerated Project Delivery and Less Delays – The early identification and solving of the problems prevent construction delays and accelerate the project delivery.
Reduced Waste and Efficient Materials Planning – The resolution of clashes in advance allows to order the materials precisely and minimize their waste.
Better Site Safety and Maintainability – Soft clash detection ensures safety clearances and accessibility of the equipment for maintenance.
Improved Project Quality and Client Satisfaction – Well-coordinated project from the very beginning provides high-quality results and customer satisfaction.
Best Practices for Effective Clash Detection
For successful clash detection, it is essential to use best practices that allow getting the most value from it.
Perform clash checkups regularly and at the early stages of work – Clash detection should start from the early design stages and continue until the end of construction. Regular checks will reveal potential problems before they become deeply embedded.
Use clean and well-structured models – Properly named models, correct coordinates, and clean geometry give much more accurate results of clash detection.
Adjust tolerance settings to reduce false positives – Very strict tolerances cause generation of too many false positive clashing results; loose tolerances will lead to missing real clashing issues. Try to find a good compromise for your project.
Organize clashes by groups to avoid double detections – Group clashes by their types, locations, or disciplines to facilitate review and further clash resolution.
Designate a person responsible for resolution of each clash – It is important that each detected clash will have its owner who is responsible for its solution.
Repeat detection process after every substantial change of the model – New clashes will appear when your model changes; regular repeat of detection process ensures that you will catch them in time.
When to Outsource BIM Clash Services
There are cases when outsourcing BIM clash detection services is quite beneficial for project success.
Firms which have no in-house BIM coordination capacities can gain much from the skills and equipment provided by special service providers. Large-scale or multi-discipline projects often require many additional coordination resources that internal team cannot provide. Quick generation of reports is necessary when fast turnaround is required. Sometimes expert model analysis is required; in such situations you should choose a specialized provider.
Outsourcing helps design and construction teams to concentrate on what they do best – to design and construct projects – and to leave the difficult coordination works for specialists.
Conclusion
BIM clashes are natural in complex construction projects. Designing various systems by different disciplines in one physical space inevitably leads to the clashes occurrence. However, clashes are manageable with the help of appropriate process, technologies and skills.
Professional BIM clash detection services will help to prevent any possible problem in advance. Identification and solution of design issues before construction ensures you from unnecessary rework, time loss, and delays; it will help to increase quality of the project. Investment into BIM clash detection pays itself back many times due to reduction of change orders, improvements of coordination and speeding up of project delivery.
No matter if you are an architect, engineer, contractor, or consultant, effective BIM clash detection should become integral part of your work process. The only thing which is unknown for you is not whether you will face BIM clashes or not.
Frequently Asked Questions
1. What is the difference between BIM clashes and clash detection?
BIM clashes are the conflicts or conflicts between model elements, while clash detection is the process of their identification before construction.
2. What are the three types of BIM clashes?
There are three types of them: hard, soft, and workflow clashes. The first type is the physical overlaps; the second is related to clearance and access issues; the third is connected with schedule.
3. Why is clash detection important in BIM?
It will help you to identify design issues, reduce rework, improve coordination, save money and time and avoid construction delays.
4. Which software is used for BIM clash detection?
There are many special tools including Navisworks and other BIM coordination platforms which support model aggregation, clash detection and issue tracking.
5. Can clash detection identify soft clashes?
Yes. Modern BIM clash detection can identify clearance and access-space issues if model and clash rules are correctly defined.
6. Should firms use BIM clash detection services?
Yes, especially if they need specialized knowledge, quick turnaround or coordination on complex multi-discipline projects.
Need Professional BIM Coordination Help?
BIM clash detection requires appropriate set of skills, technology, and process. If you are seeking for professional assistance in keeping your project in order and avoiding costly rework, we suggest you to contact BIM coordination specialists.
Contact CAD Drafting Services today to find out how our BIM clash detection and coordination services can help you to implement your project successfully.