 In August 2004, SLA introduced the faster and more accurate coordinated cadastre system, called SVY21, to replace the old land survey system. The new system defines legal property boundaries by determining coordinates of all measured boundary points to derive information on a piece of property.
Having gazetted the coordinates of all lots in Singapore, the coordinated cadastre is legally valid as set out under the provisions of the Boundaries and Survey Maps Act. SVY21, which is based on the coordinated cadastre concept, is introduced to replace the Cassini-Soldner system. SVY21 provides many advantages over the Cassini-Soldner system in terms of surveying, namely,
- Establishing a homogeneous ISN network, enabling surveying to be more consistent
- Simplifying surveying procedures and documentation
- Enhancing the use of IT in surveying through E-submission
- Enabling a survey work to be carried out in a shorter time and at a reduced cost
- Enabling the use of Global Positioning System (GPS)
SVY21 is a system of cadastral surveying based on a set of parameters and conditions, including a specific datum and projection. The datum used is the WGS84 ellipsoid and the projection is based on the Transverse Mercator Projection. It supports GPS, one of the leading technological forces driving the acquisition of spatial information.
One of the defining infrastructures supporting SVY21 is the Integrated Survey Network (ISN), which is a homogeneous control network consisting of approximately 70 primary and 5,000 secondary control points spread throughout Singapore. These control points are set up using GPS technology and form the base for conducting land surveys under the new system.
Government agencies with spatial information databases referencing the cadastral base have to conform to SVY21. SLA had been surveying and converting lots to the new system and are providing various agencies, such as the Land Transport Authority and Power Grid, with transformation parameters that would help them convert their spatial information to SVY21. At the same time, organisations using cadastral maps from SLA as base maps for their operational needs are required to convert their digital maps to reference the SVY21 system.
If you belong to any of these categories, namely registered surveyors, providers of location-based services, GIS specialists, engineers or property buyers/sellers, you can also benefit from the new system!
All registered surveyors need to know about the change to the SVY21 system as they will be the first to benefit from the new system.
LBS providers need to know the coordinate system which their spatial information is referencing.
GIS specialists have to understand how spatial information will be represented in their GIS system.
Engineers can use ISN marks and GPS surveying in their engineering projects.
When a new property is transacted, cadastral surveying could be required. Due to changes in surveying procedures, property buyers/sellers would indirectly benefit from the new system.
With the coordinates of the whole of Singapore gazetted under the Boundaries and Survey Maps Act in August 2004, cadastral surveying is now based on the SVY21 system.
As a technology-driven profession, we need to utilise the latest technology to improve our work procedures. The world is moving towards positioning techniques using GPS. As such, we should also move forward to utilise GPS as a tool to make our surveying activities more efficient.
The coordinated cadastre system, SVY21, which supports GPS, is introduced to facilitate the integration and sharing of information across various sources. Information provided is therefore more uniform and less confusing to users.
As we move from local to global, we need a reference system that is comparable with the world. GPS coordinates are based on a geocentric datum (WGS84), thus making our system comparable with other countries using the same datum.
A host of opportunities has thus opened up with the implementation of SVY21. Among them is the launch of the Singapore Satellite Positioning Reference Network (SiReNT) in September 2006. SiReNT is a nation-wide infrastructure, physically represented by 5 GPS reference stations strategically located in Singapore, supporting real-time high precision surveying and positioning applications.
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