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Singapore Land Authority

Survey Reference System

In 2004, SLA introduced the Co-ordinated Cadastre system to replace the old land survey system. The new system defines property boundaries by co-ordinates, rather than bearings and distances.

Last updated 20 January 2026

Survey control network

SLA has established the land survey control network as the infrastructure to support survey work conducted by all Registered Surveyors. This allows all land lots in Singapore to be geographically linked to each other and to the whole of Singapore. We maintain 2 types of survey control, namely the Horizontal Control Network and Vertical Control Network.

Horizontal control network

There are two categories of horizontal control: Primary and Secondary control network. As a whole, they are known as the Integrated Survey Network (ISN).

The primary control network consists of about 39 points that are strategically located in Singapore, most of which are on top of HDB flats, to cover the entire area of the island.

The secondary control network comprises more than 5,000 points, which are mostly found on the ground along major roads for easy access.

Vertical control network

The vertical control network consists of physical points on the ground known as Precise Levelling Benchmarks (PLBM). There are about 400 PLBMs located at 1 km intervals along major roads. PLBM information is used to determine heights of locations in Singapore.

You can gain access to horizontal and vertical control network information here

Positioning with Global Navigation Satellite System (GNSS)

The Singapore Satellite Positioning Reference Network (SiReNT) is a national reference network infrastructure, developed to support real-time high precision Positioning, Navigation and Timing (PNT). An initiative by Singapore Land Authority (SLA), SiReNT supports GNSS (Global Navigation Satellite System) systems such as NAVSTAR GPS, GLONASS, QZSS, Beidou and Galileo. It provides Real-time Kinematics (RTK), Differential GNSS (DGNSS) and Post Process On-Demand (PP On-Demand) services which improve the accuracy, precision and reliability of satellite positioning. The network consists of 10 GNSS reference stations with round-the-clock availability, of which 9 are available to SiReNT users.

SiReNT is used to enable high precision and accuracy applications that include surveying and mapping, self-mobility vehicles development, construction automation, geodata capturing and asset management, amongst many others.

For more information on SiReNT, please visit the SiReNT website at https://app.sla.gov.sg/sirent/.