TLDR: FORTRESS is a novel AI architecture designed for real-time structural defect segmentation in civil infrastructure. It addresses the challenge of balancing high accuracy with computational efficiency by combining parameter-efficient depthwise separable convolutions with adaptive Kolmogorov-Arnold Network (TiKAN) integration and multi-scale attention fusion. The model achieves state-of-the-art segmentation performance with significantly reduced parameters (91% reduction) and computational complexity (91% reduction), leading to a 3x inference speed improvement compared to conventional methods. This makes FORTRESS a robust and practical solution for automated infrastructure inspection in resource-constrained environments.
Maintaining the safety and efficiency of civil infrastructure, such as bridges, tunnels, and buildings, is a monumental task. Traditional manual inspections are time-consuming, labor-intensive, and prone to human error. While automated inspection technologies, particularly those leveraging computer vision and deep learning, have shown promise, they often face a critical trade-off: achieving high accuracy versus maintaining computational efficiency for real-time deployment.
Many existing deep learning models, like the widely used U-Net, can be highly accurate but demand significant computational resources, making them impractical for deployment in resource-constrained environments or on edge devices. On the other hand, lightweight models, while efficient, often compromise on segmentation performance. This challenge is further complicated by the complex and varied nature of structural defects, which can be subtle, multi-scale, and easily obscured by environmental factors.
A new research paper introduces FORTRESS (Function-composition Optimized Real-Time Resilient Structural Segmentation), a novel artificial intelligence architecture designed to overcome this fundamental trade-off. FORTRESS aims to deliver both superior accuracy and remarkable computational efficiency for automated structural defect segmentation.
How FORTRESS Achieves Its Goals
FORTRESS incorporates three key innovations to achieve its impressive balance of performance and efficiency:
- Systematic Depthwise Separable Convolutions: This is a special method of performing convolutions, the core operation in many neural networks, that significantly reduces the number of parameters and computational load per layer. For instance, it achieves a 3.6 times parameter reduction in convolutional layers compared to standard methods.
- Adaptive TiKAN Integration: FORTRESS selectively applies a powerful function composition technique from Tiny Kolmogorov-Arnold Networks (TiKAN). Unlike traditional neural networks that use fixed activation functions, KANs model complex relationships through compositions of learnable one-dimensional functions. TiKAN makes these networks viable for large-scale applications by being parameter-efficient. FORTRESS uses this adaptively, applying these transformations only when it’s computationally beneficial, for example, at certain feature resolutions.
- Multi-Scale Attention Fusion: The architecture combines spatial, channel, and KAN-enhanced features across different levels of its decoder pathway. This allows the model to focus on relevant spatial regions and recalibrate feature responses, improving its ability to recognize complex defect patterns at various scales.
Breakthrough Performance
The evaluation of FORTRESS on benchmark infrastructure datasets, including the challenging Culvert Sewer Defect Dataset (CSDD) and the Structural Defects Dataset (S2DS), demonstrates state-of-the-art results. On the CSDD, FORTRESS achieved an F1-score of 0.771 and a mean IoU (Intersection over Union) of 0.643, outperforming previous leading methods like SA-UNet. Crucially, it accomplished this while requiring significantly fewer resources: a 91% reduction in parameters (from 31 million to 2.9 million) and a 91% reduction in computational complexity (from 13.69 to 1.17 GFLOPs), leading to a 3 times improvement in inference speed.
This means FORTRESS can process images much faster and with less computing power, making it highly suitable for real-time deployment on devices with limited resources, such as drones or robotic inspectors. Its robustness was further highlighted in ablation studies, where it maintained strong performance even when trained with only 50% or 25% of the available data, showcasing its data efficiency.
The visual analysis of FORTRESS’s segmentation capabilities confirms its exceptional accuracy in detecting and delineating diverse structural defects, including thin, irregular cracks and large-scale defects like holes and fractures, across various lighting conditions and surface textures.
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Future Implications
FORTRESS represents a significant step forward for automated infrastructure inspection. Its ability to balance high accuracy with computational efficiency makes it a robust solution for practical structural defect segmentation in real-world, resource-constrained environments. The researchers suggest future work could involve making the KAN integration even more dynamic, extending the model to handle multi-modal data (like thermal or LiDAR), integrating it with federated learning for on-device training, and enhancing its explainability to provide civil engineers with deeper insights into defect analysis.
For more detailed information, you can refer to the full research paper: FORTRESS: Function-composition Optimized Real-Time Resilient Structural Segmentation via Kolmogorov-Arnold Enhanced Spatial Attention Networks.


