Private projects over HK$30 million carry Buildings Department conditions for a Mobile Plant Alert System and a Tower Crane Alert System, specified by sensor performance. AI on your existing cameras adds a second layer.
Imposed as qualified supervision conditions under item 6 of section 17(1) of the Buildings Ordinance. Public works follow DEVB's own 4S circular.
BD Circular Letter, 28 Mar 2024
BD Circular Letter, 31 Mar 2025
BD Circular Letter, 30 Mar 2023
BD 4S FAQ
The alert systems are sensor based. A safety monitoring system using AI is one of the other 4S devices BD encourages (CL 2023, para 2(g)).
BD: Sensors with 360 degree coverage; zone at least 2m from the plant.
On your cameras: Person-in-zone alert from fixed cameras, beside the plant sensors.
BD: At least 7m radius from the hook, at every loading floor.
On your cameras: Person-under-suspended-load alert at landings a camera sees.
BD: Where sensors are not needed, crowd management keeps people out.
On your cameras: Every zone entry logged with time and clip.
BD: BD checks the implementation plan and TCP records.
On your cameras: Findings assigned and closed, with trends by zone and shift.
BD: Excluded from the mobile plant definition.
On your cameras: Forklift and vehicle proximity alerts.
BD: Strongly encouraged as far as practicable.
On your cameras: Missing PPE, work at height without edge protection, worker down.
BD's alert systems use sensors on the plant and crane, and camera AI does not replace them. BD treats CITF Pre-approved List products as generally acceptable; confirm anything else with BD and your AP.
No. The conditions cover two alert systems specified by sensor performance. A safety monitoring system using AI is among the other 4S devices BD encourages, not a mandatory item.
Projects whose total estimated building works cost exceeds HK$30 million, including alteration and addition works with structural works.
DEVB TC(W) No. 3/2023 is for reference only on private works, and BD does not require its central platform or recording (FAQ Q12).
Usually yes, if they stream over RTSP or ONVIF. The plant and crane sensors stay in place.
Send recorded footage of your plant and crane zones and we show you what it would have flagged, free.