AI-Powered CCTV · Construction · NX Witness
How we deployed an intelligent CCTV and AI analytics system across an active high-rise construction site — reducing safety violations by 74% in 90 days.
The client was a growing construction firm managing a 28-storey mixed-use development in an urban centre. With over 120 workers on site at peak, spread across multiple floors, a tower crane operation, and a busy site entrance shared with public footpaths — their existing CCTV system was purely reactive. Cameras recorded. Nobody watched. Incidents were reviewed after the fact, not prevented.
Following two near-miss incidents in a single quarter, the project director needed a system that could act as a permanent, tireless safety presence across the entire site.
PPE Non-compliance
Workers removing hardhats and hi-vis vests in active zones, undetected until incident review.
Exclusion Zone Breaches
Crane lift areas and excavation perimeters regularly accessed without authorisation.
After-hours Intrusion
Perimeter hoarding breaches overnight leading to tool theft and site liability concerns.
No Visibility on Progress
Management had no reliable way to remotely track site progress or validate subcontractor activity.
We designed a layered CCTV and AI analytics deployment using NX Witness as the VMS backbone, with Nx AI Manager handling model orchestration. The system was built in four integrated phases.
Phase 1 — Infrastructure & Fixed Camera Network
Installed fixed IP cameras at all perimeter hoarding points, the site office block, welfare facilities, and the tower crane — covering the counter-jib, operator cabin approach, and crane base exclusion zone. Cameras selected for wide dynamic range to handle Singapore's harsh contrast between shade and direct sun.
Perimeter · Office · Tower CranePhase 2 — Mobile CCTV Deployment
Deployed two rapid-deploy mobile CCTV units on battery and solar power for internal site coverage at the active working floor and hoisting bay. Units were repositioned weekly as construction progressed upward — giving us eyes on the most dangerous active work zones at all times.
Mobile Units · Hoisting Bay · Active FloorPhase 3 — NX AI Manager Integration & Model Tuning
Deployed and configured three AI analytics pipelines on NX Witness: PPE/hardhat detection, person & vehicle detection, and perimeter intrusion. Critically, we spent two weeks tuning — drawing precise ROI polygons per camera, calibrating confidence thresholds to the site's specific PPE colour palette, and establishing day/night rule scheduling to eliminate false alarm fatigue.
AI Analytics · ROI Tuning · Rule SchedulingPhase 4 — Exclusion Zone Enforcement Layer
Built a dedicated exclusion zone rule set on top of existing person detection — flagging any person detected within the crane lift radius during active lifts, within 2m of excavation edges, and within scaffold base zones without simultaneous hardhat detection confirmation.
Exclusion Zones · Compound Rules · Crane Safety| Analytics Module | Coverage | Key Configuration |
|---|---|---|
| PPE Detection | 8 cameras — all active work zones | Confidence set to 68%; yellow & orange hi-vis classes separated; 75-sec cooldown per zone |
| Perimeter Intrusion | 6 cameras — full hoarding perimeter | Direction-of-travel filter (inbound only); night mode high sensitivity 19:00–06:00; linked to mobile PTZ |
| Person & Vehicle Detection | 4 cameras — entrance, hoisting bay, crane base | Separate event streams per class; vehicle proximity alert within 5m of active crane zone |
| Exclusion Zone Rules | Crane lift area, excavation, scaffold base | Compound rule: person detected + no hardhat confirmed = immediate alert; crane lift schedule-linked |
Reduction in recorded PPE non-compliance incidents
After-hours perimeter breaches in the final 6 weeks of review period
Reduction in false positive alerts after ROI tuning vs. week one
Beyond the safety metrics, the client's project director gained remote visibility into site activity through the NX Witness mobile app — able to pull live feeds and AI event logs during off-site management meetings. The system also provided timestamped site progression footage used to resolve a subcontractor attendance dispute, saving the firm a potential contractual penalty.
"Before this system, we were reviewing cameras after something went wrong. Now the system tells us when something is about to go wrong. That's a completely different posture for site safety — and honestly, it's changed how our safety officer does his job."
Project Director · High-rise Residential Development