In Singapore, settlement monitoring is a regulatory requirement for ERSS and tunnelling works. The Qualified Person (QP) must prepare an approved instrumentation and monitoring plan that covers geotechnical parameters and specifies the reporting frequency. Where public sewers or the deep tunnel sewerage system (DTSS) are affected, PUB concurrence and a Construction Impact Assessment Report (CIAR) are also required.
TL;DR:
- Before work starts, the Qualified Person must establish the base set from the average of three independent readings and document instrument calibration.
- The plan should select measurements relevant to the site, including settlement, pore pressure, water table, ground stress, and tunnel face pressure where applicable.
- The plan should increase monitoring frequency during excavation and tunnelling and define staged numeric triggers, notification contacts, required actions, and restart conditions.
- For work affecting public sewers at least 900 mm wide or DTSS structures, obtain PUB concurrence on the plan and a CIAR before starting.
- If monitoring exceeds PUB’s allowable limits, work must stop immediately; agreed trigger exceedances also require immediate notification to the Engineer under the LTA specification.
Table of Contents
- Which projects need settlement monitoring under Singapore law
- Who is responsible: the QP, the Accredited Checker and site supervision
- What to monitor: core geotechnical parameters
- Instrumentation and methods used on Singapore sites
- Designing the monitoring plan: baseline, frequency, triggers and reporting
- PUB requirements near public sewers and DTSS
- Templates, forms and a practical submission checklist
- Where monitoring plans go wrong in the field
- How we help with plans, QP/PE services and submissions
- FAQ
- Sources
Which projects need settlement monitoring under Singapore law
The legal anchor is the Building Control Act, with detail in the Building Control Regulations. They require the QP to determine instrumentation and monitoring for geotechnical parameters, considering the location, type and number of instruments and the frequency of monitoring and reporting. Results must be assessed at every critical stage to confirm the geotechnical aspects stay within design assumptions.
In practice, monitoring requirements depend on the works and the approved plan. ERSS and tunnelling works are among the activities addressed by the regulations.
BCA’s permit for structural works page lists the BEV templates that frame each submission. Our ERSS submission checklist walks QPs through the documents that accompany them.
The approved plan must cover relevant geotechnical parameters and specify the reporting frequency.
Who is responsible: the QP, the Accredited Checker and site supervision
Responsibility is split, and each role has a distinct job.
- Qualified Person: prepares the instrumentation and monitoring plan.
- Accredited Checker (Geo): under the Accredited Checkers Regulations, reviews the adequacy of monitoring, monitoring results and site conditions, as well as site investigation scopes and relevant geotechnical parameters.
- Site supervision and contractor: follow the project’s approved arrangements for instrumentation, readings and reporting.
A plan that nobody on site owns tends to fail quietly. Name a responsible person for each instrument group before excavation starts.
What to monitor: core geotechnical parameters
The Regulations list the parameters the plan should consider: ground deformation and settlement, pore water pressure, water table level, ground stresses and, for tunnelling, face pressure. The parameters selected should be relevant to the works and the geotechnical aspects being monitored.
Each parameter answers a different question. Settlement readings show whether adjacent ground and structures are moving. Pore pressure and water table readings provide additional information about ground conditions.
Decide early whether you are measuring absolute or relative movement. Absolute readings tie back to a fixed datum, while relative readings compare against a base set. LTA’s materials and workmanship specification requires that base set to be the average of three independent readings taken before work starts.
Parameter selection should be justified site by site. Map the zone of influence, list the assets inside it, and choose parameters that protect those specific assets rather than copying a template.
Instrumentation and methods used on Singapore sites
Common choices include settlement plates and points, extensometers, piezometers, inclinometers, tiltmeters, total stations, precision levelling, GNSS and crack monitors. Our field guide to geotechnical instrumentation compares them in more detail, and our article on settlement monitoring methods covers survey and GeoAI approaches.
Automated dataloggers with real-time alerts earn their cost during high-risk phases such as excavation and tunnelling. Manual surveys remain sensible for baselines and lower-risk periods, a split the CICES client guide also describes, tying frequency and instrument choice to construction method and asset sensitivity.
Verification matters as much as selection. Calibrate instruments, confirm that reference points have not moved, and check the accuracy band of the whole system before you rely on a trigger level that sits close to it. Digital capture tools, such as the on-site measurement workflows described by Won2Build, help keep readings and records in one place.
Designing the monitoring plan: baseline, frequency, triggers and reporting
A plan that satisfies BCA and PUB, and works in the field, contains these elements:
- Baseline: the average of three independent readings, recorded as the base set before work begins.
- Frequency: highest during excavation or tunnelling, and eased as the structure stabilises. Reporting intervals can be longer than measurement intervals while still showing trends.
- Trigger levels: numeric thresholds, usually staged, set by the QP.
- Escalation: who is notified, how fast, and when work stops.
- Reporting format: a tabular base set, relative movement in millimetres, and graphs against time.
Exceedance rule: under the LTA specification, agreed trigger levels mean the Engineer is notified immediately when they are exceeded, so the notification route must be written down and tested before the first excavation lift.
An escalation matrix should read like a phone tree with consequences: the reading, the person called, the action taken, and the condition for resuming. Our geotechnical analysis guide sets out how these steps fit a wider verification process, and our piece on managing ERSS risk in deep excavations shows how they play out on deep cuts.
PUB requirements near public sewers and DTSS
When works affect public sewers of 900 mm diameter or larger, or DTSS structures, PUB expects a CIAR and a detailed instrumentation and monitoring programme. The Code of Practice on Sewerage and Sanitary Works requires the QP or PE to submit the instrumentation plan for PUB concurrence before work starts.
Check the current Code and PUB submission guidance for the supporting documents required for your project.
If monitoring exceeds PUB’s allowable limits, work must stop immediately. Treat that as a hard stop, not a discussion point.
Templates, forms and a practical submission checklist
BCA publishes BEV templates for each work type: BEV_ERSS for earth retaining and stabilising structures, BEV_PC for piling and BEV_TUN for tunnelling. They sit alongside the site supervision plan templates on BCA’s structural works permit page.
Before submitting, confirm that your package includes:
- Base readings and the instrument calibration records
- Monitoring intervals and numeric trigger levels
- CCTV or video records where required
- Stakeholder contacts and the escalation matrix
Where required by the Regulations, site investigation works must be carried out by a SAC-accredited inspection body.
Where monitoring plans go wrong in the field
Potential problems include reference points that have not been checked for stability, an inadequately established baseline, unclear trigger actions, and late communication with neighbors or asset owners. Each is cheap to fix before excavation and expensive afterward.
Early contact with asset owners, and with PUB where sewer corridors are involved, can help coordinate the project. A consultant who has already worked through BCA and PUB comments will write the plan to survive them.
— Aman
How we help with plans, QP/PE services and submissions
We prepare instrumentation and monitoring plans, provide structural and geotechnical QP and PE services, and manage BCA, BEV and PUB submissions, including CIAR support. If you are scoping a deep excavation or a project near a sewer corridor, ask us for a compliance review through our geotechnical consultancy team. Current pricing details are on our website.
FAQ
Is settlement monitoring mandatory in Singapore?
Yes, for ERSS and tunnelling works, and for other works where the Regulations require instrumentation and monitoring. The QP prepares the plan and the Building Control Regulations require results to be assessed at every critical stage.
What parameters must a monitoring plan cover?
It must address the geotechnical parameters relevant to the works, including ground deformation, pore pressure, water table level and, for tunnelling, face pressure. The parameters selected should be relevant to the works and the geotechnical aspects being monitored.
How is the baseline established?
Take the average of three independent sets of readings before work starts and record it as the base set. This follows the LTA specification.
What happens if a trigger level is exceeded?
Notify the responsible parties immediately and follow the escalation matrix in the approved plan. Where PUB limits are exceeded, work must stop immediately.