École de technologie supérieure — Academic Award Winner 2024

Clash Avoidance and Improved Model Quality with Rule-based Expert System

The construction industry increasingly relies on BIM coordination to integrate architectural, structural, and MEP systems into a unified model. This integration, however, is often hindered by clashes—conflicts in the model where two or more elements overlap improperly. Traditional clash detection processes identify these issues “after the fact”, resulting in rework, project delays, and additional costs. With the advent of advanced technologies and the industry's growing demand for accurate project delivery with the highest efficiency, a novel proactive clash management solution has become essential.

While current BIM-based clash detection systems contribute to cost savings, the high incidence of irrelevant clash detections and the lack of mechanisms to prevent recurring clashes imposes a substantial strain on project resources. Studies indicate that clash management can account for up to 20% of contract costs, driven by the resources needed for post-detection clash resolution. Furthermore, the escalating number of clashes in federated BIM models can compromise model quality and complicate collaboration. As BIM technology evolves and the number of detected clashes increases, they create an industry-wide challenge: how to minimize clash instances and the need for manual intervention for clash management effectively. Our innovation addresses this challenge by shifting from reactive clash detection to proactive “before the fact” clash avoidance with an automated system for real-time clash avoidance.

High-Level Solution

The presented solution leverages a rule-based expert system to encode clash prevention strategies in the form of design rules within BIM authoring tools, providing real-time feedback to designers. Unlike traditional systems that identify clashes post-design, this system incorporates expert knowledge and lessons learned directly into the BIM model creation phase. Using Revit as the platform for the plugin, we developed an application programming interface (API) that applies C#-coded rules based on insights from industry experts. This approach enables the system to be highly scalable and adaptable across various disciplines and project types, supporting broad industry applications.

This proactive approach aligns with industry trends prioritizing efficiency, collaboration, and early clash prevention. Competing technologies lack preventative power to reduce clashes, as they mainly focus on post-design clash detection, identifying issues only after modeling. By combining rule-based automation with adaptive, expert-guided insights, our approach learns new rules over time, applying them in future projects to prevent recurring clashes. This forward-thinking solution efficiently bridges the gap between traditional clash detection and real-time clash avoidance.

Solution Details

The core concept of this proactive clash avoidance approach centers on a rule-based expert system that embeds expert knowledge directly into the design phase via a Revit-based plugin. Key features and functionality include:

1. Rule Integration and Knowledge Base: Through multilevel interviews conducted with construction experts across architectural, structural, and MEP disciplines, 35 expert-driven rules were established to prevent clashes during BIM modeling phase. These rules were validated by cross-referencing their efficacy with additional experts, resulting in a refined, effective set of design standards.

2. Real-Time Feedback Mechanism: As designers work, the plugin monitors model elements in real-time, issuing immediate warnings or error prompts if deviations from clash prevention rules are detected, along with related element IDs and suggested corrective actions. The system offers an "explanation module" that explains flagged issues and allows designers to override or accept suggestions, with an override counter for managerial review to ensure accuracy and trust in the system.

3. IFC Standard Compatibility: Utilizing the Industry Foundation Classes (IFC) standard for data exchange, the system ensures seamless interoperability, allowing data to be shared consistently across various platforms. By supporting open standards, data fidelity is maintained, enhancing collaboration and minimizing information loss during data transfers.

4. Adaptability and Continuous Improvement: The rule-based framework is adaptable, with rules and system knowledge base being modifiable to align with evolving industry standards or project-specific needs. This flexibility makes the system scalable across different projects and disciplines, increasing its applicability and long-term relevance.

5. Quantitative and Qualitative Results: The system was evaluated through two studies. In a qualitative assessment, users rated the system highly for ease of use and clash avoidance effectiveness. A quantitative study compared a project model utilizing the plugin to two models without it, revealing a 23% reduction in clashes, validating the system’s effectiveness in improving model quality.

Business Benefits

The rule-based expert system for clash avoidance provides a valuable solution for the construction industry with multiple benefits:

Efficiency and Cost Savings: By proactively preventing clashes, the system reduces rework, shortens project timelines, and lowers overall costs.

Enhanced Model Quality and Consistency: Real-time feedback enforces best practices, improving model accuracy and reducing the need for manual error-checking and clash resolution.

Improved ROI and Reduced Project Risk: The proactive approach to clash management yields a measurable ROI by minimizing rework, delays, and waste, reducing financial risks associated with traditional clash management.

Interoperability and Standardization: With IFC compliance, the system ensures efficient data exchange across platforms, fostering collaboration and enabling standardized workflows.

Environmental Impact: Reducing rework minimizes material waste, aligning with sustainable practices and lowering the construction project’s carbon footprint.

This system enhances clash management, promoting efficient, quality-focused BIM coordination that benefits project outcomes and sets a new standard in proactive clash avoidance.

Summary‍

The rule-based expert system for clash avoidance represents a breakthrough in BIM coordination. By embedding expert-derived design rules into the BIM authoring tool’s API, the system provides designers with real-time feedback during the designing and modeling phase, effectively preventing clashes before they arise. This proactive approach not only improves model quality but also reduces the time, cost, and environmental impact of rework associated with traditional clash detection.
This system aligns with current industry demands for sustainability, and adaptability, making it a valuable tool for any construction project involving complex, multidisciplinary coordination. As an scalable solution that utilizes open standards, it enhances interoperability, facilitates knowledge sharing, and promotes a higher standard of construction practices across the industry.

By implementing this expert system, the construction industry can address the persistent challenges of clash management, driving a more efficient, economically sustainable, and collaborative future for BIM and project delivery.