BIM based collision tracking at the intersections of different building systems: A review of current approaches

Prioritizing design of different building engineering systems

The effective design and coordination of various building engineering systems, such as structural, architectural, HVAC, plumbing, electrical, and communications networks, is crucial for reducing design errors, minimizing rework, and improving overall design productivity. To achieve these goals, a comprehensive approach is required that prioritizes the design of different building engineering systems during the model development phase. This ensures a consistent and well-coordinated design across all the interconnected systems.

One of the key challenges in this process is the identification and resolution of collisions or intersections between the various building components and systems. As these systems are designed simultaneously within a shared digital information repository, the potential for overlaps and conflicts is high. Proper management of communication and information exchange between the design team members is essential to minimize rework and avoid potential issues at the start of the project.

Collision detection and classification

Building information modeling (BIM) tools provide valuable capabilities for detecting collisions between the modeled elements. These tools distinguish between two main types of collisions: relevant and irrelevant. Relevant collisions are those that require resolution, as they can lead to productivity losses, interruptions, and rework. Irrelevant collisions, on the other hand, do not require resolution, as they may be a single error repeated multiple times or collisions that were deliberately created.

Collisions typically occur when elements from different systems or components collide with each other. Research findings indicate that collisions are most likely to occur within the range of 30-299 mm, with the 100-199 mm discrete category being the most common. This is based on predictive modeling, and the implementation of specific tolerances tailored to the type of system can prevent a significant number of unnecessary collisions.

The accurate identification of relevant and irrelevant collisions, as well as the appropriate distribution of collision resolution tasks among the BIM project teams, play a crucial role in the design process. Specialized software can capture thousands of collisions, and estimating the time required for an individual specialist to resolve a conflict can be challenging due to the varying nature of the intersecting systems and their crowding at the intersections. However, it is generally assumed that eliminating an average collision can take several minutes, and the automation of collision elimination can result in significant time savings for engineers.

Causes of collisions and current approaches

The literature review has identified several key causes of collisions in BIM-based design:

1. Incorrect or low level of detail: The use of inaccurate or low-level of detail in the BIM model can lead to collisions.
2. Uncertainty in design and use of “fillers”: Uncertainties in the design process and the use of placeholder or “filler” elements can contribute to collisions.
3. Failure to follow design rules: Not adhering to established design rules and guidelines can result in collisions.
4. Accuracy vs. timing: The balance between design accuracy and timely completion of the project can impact collision occurrences.
5. 3D model objects exceeding acceptable clearances: Modeled elements that exceed the acceptable clearances can cause collisions.
6. Designers working in isolation: Lack of collaboration and coordination among designers working in isolation can lead to collisions.
7. Complexity of the design: The inherent complexity of the building design can increase the likelihood of collisions.
8. Lack of time: Time constraints during the design process can contribute to collision issues.
9. Use of 2D rather than 3D models: The use of 2D design models instead of 3D BIM models can result in increased collisions.
10. Design errors: Mistakes and errors in the design process can lead to collisions.
11. Use of different file formats: The use of multiple file formats and incompatibilities can introduce collisions.
12. Lack of experts: Insufficient expertise and experience in the design team can increase the occurrence of collisions.

To address these issues, various approaches have been explored in the literature:

1. Collision detection algorithms: Researchers have focused on developing advanced collision detection algorithms to automate the identification of intersections between building components.
2. Network analysis: Some studies have proposed the use of network analysis techniques to enhance collision detection by considering the dependency relationships between building components.
3. Automated grouping and prioritization: Plugins and software tools have been developed to automatically group detected collisions and prioritize their resolution based on various criteria.
4. Machine learning for relevance prediction: Researchers have explored the use of supervised machine learning algorithms to differentiate between relevant and irrelevant collisions, improving the quality of the collision detection process.
5. Sequence-based design approach: A few studies have suggested prioritizing the design of different engineering systems in a specific sequence to minimize early collisions during the design stage.

Proposed methodology for collision tracking

The current research proposes a systematic approach for prioritizing the design of different building engineering systems and effectively managing the collision detection and resolution process. The key elements of this methodology include:

1. Prioritized design sequence: The design of the various engineering systems, such as structural, architectural, HVAC, plumbing, electrical, and communications, is carried out in a predetermined order to minimize the occurrence of collisions.
2. Collision detection and classification: Collision detection is performed using BIM tools, with a focus on distinguishing between relevant and irrelevant collisions. Relevant collisions require resolution, while irrelevant collisions can be excluded from further consideration.
3. Tolerance management: Appropriate tolerances are set for the joining of system elements to prevent the inclusion of technically correct but visually conflicting intersections in the collision reports.
4. Automated collision tracking and reporting: A custom plugin has been developed to automate the identification, visualization, and tracking of collisions throughout the project lifecycle. This plugin enables efficient reporting and resolution of collisions, reducing the time and effort required compared to traditional methods.

The proposed methodology has been tested and validated through a case study involving a complex data center project. The results demonstrate that the systematic approach to collision detection and resolution can significantly reduce the time required for identifying and resolving intersections, as well as eliminate duplicate collisions and optimize the reporting process.

Advantages of the proposed approach

The key advantages of the proposed methodology for BIM-based collision tracking include:

1. Prioritized design sequence: By following a predetermined order for designing the various engineering systems, the likelihood of early collisions is reduced, leading to more efficient coordination and fewer design conflicts.
2. Relevant collision identification: The distinction between relevant and irrelevant collisions ensures that the project team focuses its efforts on resolving the most critical issues, improving overall design quality and productivity.
3. Tolerance management: The implementation of appropriate tolerances for joining system elements helps to exclude technically correct but visually conflicting intersections from the collision reports, streamlining the review and resolution process.
4. Automated collision tracking and reporting: The custom plugin developed as part of this research enables faster identification, visualization, and tracking of collisions, reducing the time and effort required compared to traditional methods.
5. Scalability and efficiency: The proposed approach has been tested on a large-scale data center project, demonstrating its effectiveness in managing complex building systems and the ability to scale up for larger, more intricate projects.

By adopting this comprehensive methodology for BIM-based collision tracking, design teams can significantly improve the coordination and integration of different building engineering systems, leading to reduced design errors, minimized rework, and enhanced overall design productivity.

Conclusion

The effective design and coordination of various building engineering systems is crucial for the successful delivery of construction projects. BIM-based tools and methodologies play a vital role in this process, enabling the identification and resolution of collisions between the modeled components.

The proposed approach in this research emphasizes the importance of prioritizing the design sequence of different engineering systems, accurately classifying collisions as relevant or irrelevant, and implementing appropriate tolerances for joining system elements. The development of a custom plugin to automate the collision tracking and reporting process has been a key innovation, significantly improving the efficiency and scalability of this crucial design coordination task.

By adopting this comprehensive methodology, design teams can enhance their ability to proactively detect and resolve collisions, leading to reduced design errors, minimized rework, and improved overall design productivity. As the complexity of building projects continues to increase, the importance of effective BIM-based collision tracking will only grow, making this research a valuable contribution to the field of construction technology and project management.