## TL;DR
The $12 trillion global construction industry is one of the least digitized sectors -- and AI is changing that. Computer vision monitors safety in real-time, drones capture construction progress, and BIM digital twins compare plans to reality automatically. AI reduces accidents by 25-40% and rework costs by 15-20%.

## Core Explanation
Construction AI stack: (1) Safety monitoring -- CCTV cameras + computer vision detect PPE compliance, unsafe behaviors (climbing unprotected scaffolding), and exclusion zone violations. Real-time alerts to safety managers; (2) Progress monitoring -- drones and 360-degree cameras capture site daily/weekly. Photogrammetry generates 3D point clouds. AI compares point cloud to BIM model, detecting deviations and quantifying progress (concrete poured, steel erected); (3) Quality inspection -- AI analyzes concrete surface for cracks, checks rebar spacing from images, inspects welds via thermal imaging; (4) Schedule optimization -- AI predicts delays from weather, labor availability, and supply chain signals. Reinforcement learning optimizes resource allocation.

## Detailed Analysis
YOLOv8/DETR for construction: fine-tuned on construction-specific datasets (SODA: site surveillance; MOCS: multi-object construction scenes). Tasks: worker detection, PPE classification (hard hat, vest, glasses, boots), equipment detection (crane, excavator), and hazard zone monitoring. Automation in Construction (Elsevier) special issues (2023-2025) document deployment at major projects (Crossrail London, NEOM Saudi Arabia). BIM + AI: OpenSpace and DroneDeploy automatically align drone imagery to BIM coordinates. 4D BIM adds time dimension -- visualizes construction sequence, compares planned vs actual at each stage. Generative design: AI proposes optimal construction sequences given spatial constraints, crane positions, and material delivery schedules. Key challenges: construction sites are dynamic and unstructured (unlike factory floors), weather degrades camera images, and dust/mud obscure sensors. Edge AI processing on-site (no cloud dependency) addresses connectivity in remote sites.