DEVB TC(W) Nos. 3/2023 and 8/2025
4S and DWSS integration: one hub for site safety data
Where a contract adopts both systems, DEVB TC(W) No. 8/2025 says the centralised management platform of the Smart Site Safety System (4S) shall be amalgamated into the DWSS as one Smart Construction Management hub (paragraph 7, footnote 1). Every 4S alert then reaches the DWSS dashboard with its media, date, time and location. Kodifly's SpatialSense is both.
What the two circulars say
TC(W) No. 3/2023 says that, for cost effectiveness, the centralised management platform (CMP) of a Smart Site Safety System may amalgamate with the Digital Works Supervision System (paragraph 5, footnote 1). TC(W) No. 8/2025 goes further. For contracts that adopt both, the CMP shall be amalgamated into the DWSS to form an integrated Smart Construction Management hub for safety, progress, deformation, material, machinery and environment (paragraph 7, footnote 1).
The DWSS has three core components. Smart Construction Management is the data hub for smart site applications, and Annex A, clause 1.3.1, says it collects, consolidates and centralises data from IoT devices, remote sensors, AI applications and smart carry-on devices. For safety monitoring, clause 8.2.1 names AI cameras, wearables and the other devices required under the Smart Site Safety System.
The contract documents adjust to match. Annex A of TC(W) No. 3/2023 says the CMP requirements are then incorporated into the DWSS with necessary adaptation, and Annexes B and C say to amend the CMP payment item or fold it into the DWSS item. The devices stay a separate cost: the provision of smart site applications does not form part of the DWSS (TC(W) No. 8/2025, paragraph 12, footnote 2).
How CMP duties line up with DWSS hub duties
Two circulars, one set of behaviours on screen.
| 4S requirement (TC(W) No. 3/2023, Annex A) | DWSS requirement (TC(W) No. 8/2025, Annex A) | What it means on site |
|---|---|---|
| Receive, manage and record alerts from every component (5(12)(a)(i)) | Collect and consolidate data from all smart site applications (1.3.1) | Every device feeds one hub. |
| Highlighted pop-up warnings with details and follow-up actions (5(12)(a)(iii)) | Real-time alerts to responsible officers by API or real-time protocols, by system email or Mobile App push (8.1.2) | A supervisor sees the alert in the app and in the inbox. |
| Display video, audio, image and data (5(12)(a)(iii)) | Photographs, short videos, date, time, location, type and parties recorded with each event (8.2.2) | Each event keeps its media and context. |
| Dashboard with a unique web link (5(12)(a)(v)) | Dashboards filtered by application, period, area, user and alert status (8.1.3, 8.3.1, 10.2.7) | One dashboard, filtered by area or trade. |
| Storage of at least 3 months (5(12)(a)(vii)) | Media in a file store linked to the database by path and metadata (8.2.4) | Events are indexed and searchable. |
| Timestamped data available by API (5(6)) | API libraries for authorised parties, and data to iCWP within 24 hours (11.1.1, 1.7.2) | 4S data can reach the employer's systems. |
| 99.9% uptime during working hours (clause 1(3)) | 99.9% uptime during working hours (2.4.4) | One uptime commitment for both. |
How one 4S alert travels into the DWSS
Detect
A device sees a person enter a danger zone, a permit expire or a lock forced open.
Warn
Siren and red light at the scene, to the standards in Annex A clause 5(12).
Record
The alert reaches the hub with ID, date, time, location and video where specified.
Notify
Site supervisors and the Safety Officer get an SMS or in-app pop-up.
Count
The response is logged and counted in the safety statistics, such as unauthorised entries to restricted zones (8.3.2).
What Kodifly delivers as one project
SpatialSense is built as a DWSS and runs the 4S platform, so there is nothing to join afterwards.
One platform, one record
One SpatialSense platform for 4S and DWSS
Every 4S device feeding the same hub
Safety dashboard with filters by area and trade
Permit-to-work beside site safety inspection records
Alerts by app and email
API access for the employer and iCWP
One security and uptime assurance
Acceptance, handover and audit for both
4S and DWSS integration, answered
Can the 4S platform and the DWSS be one system?
Yes. TC(W) No. 3/2023 allows the CMP to amalgamate with the DWSS for cost effectiveness (paragraph 5, footnote 1). TC(W) No. 8/2025 says it shall where a contract adopts both (paragraph 7, footnote 1).
Which data must reach the DWSS hub?
Data from all smart site applications deployed on site (Annex A, clause 1.3.1). For safety, the examples are intrusion into dangerous or restricted zones and misbehaviour detected by AI cameras and wearables, plus other 4S devices (clause 8.2.1).
How are alerts delivered?
To responsible officers in real time, through APIs or real-time protocols, by the dedicated system email address or push notification to the Mobile App (clauses 6.2.1 and 8.1.2). 4S clause 5(12) adds SMS or in-app pop-up to site supervisors and the Safety Officer.
What must the safety dashboard show?
Key metrics of smart applications, for example the number and details of unauthorised entries to restricted zones. It may also give access to photographs and video of historical events (clauses 8.3.2 and 8.3.3).
Does the 4S cost count in the DWSS cost limit?
No. The DWSS cost does not include the smart site applications (TC(W) No. 8/2025, paragraph 12, footnote 2). The 4S cost has its own limit of HK$10 million or 1%, whichever is lower, and is outside the computer facilities estimate (TC(W) No. 3/2023, paragraph 10).
What changes in the contract documents when the two are merged?
The CMP requirements move into the DWSS with necessary adaptation. The CMP payment item and method of measurement are amended or included in the DWSS item (TC(W) No. 3/2023, Annexes A, B and C, notes).
Related guides
One hub for 4S and DWSS
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