A Unified Edge-Based Framework for Construction Safety: Expert-Calibrated Spatial Fusion, REBA-Driven Ergonomics, and Automated Incident Response

The construction sector still faces a high incidence of fatal accident and ergonomic injury risk, largely due to the inherent limitations of traditional manual safety auditing. While computer vision (CV) provides a viable solution to this problem, traditional deep learning architectures have struggled to balance the parametric requirements of micro-object detection, such as safety masks, with the stringent hardware limitations of traditional computer vision solutions. Furthermore, traditional spatial detectors are unable to assess active biomechanical safety risk and manage automated incident reporting without compromising inference latency. To address this critical gap in safety auditing, this research introduces a novel unified cyber-physical system using a Tri-State Routing Engine. By stratifying a dataset in a deterministic manner to prevent micro-object parametric starvation, the system dynamically routes inference using a hardware-aware Hybrid Ensemble of YOLO11 and YOLO11m backbones. The spatial inference of overlapping regions is mathematically fused using a custom-designed Expert-Calibrated Weighted Boxes Fusion (EC-WBF) algorithm to completely eliminate semantic hallucinations and deliver a peak mAP@50 of 0.910. The system also bridges passive spatial detection and active kinematic tracking using a novel routing mechanism to dynamically crop worker tensors and route them to a lightweight YOLO11n-pose network. This allows simultaneous multi-target Rapid Entire Body Assessment (REBA) ergonomic tracking and extrapolates Implicit Geometry failsafes to account for missing PPE even in severe visual occlusion. The system also introduces a novel natively coded asynchronous Robotic Process Automation (RPA) daemon. This daemon runs completely decoupled from the GPU-bound visual inference loop and sustains 14.2 FPS on severely constrained local edge hardware with 4 GB VRAM, instantaneously sending Tier 1 life safety alarms for kinematic falls and compiling Tier 2 admin compliance digests, thereby successfully closing the cyber-physical loop.