Volume 6 – Geotechnical Manual, Site Investigation and Engineering ...

Chapter 3 TYPES OF SURVEY
3.3 SURVEY NETWORKS
Horizontal and vertical survey control within a country like Malaysia was established by a network of
control arcs, which are all referenced to a single datum and are therefore linked in position and
elevation to each other, regardless of their distance apart. These networks for topographic mapping
are referenced to the KERTAU Datum for the Malayan Revised Triangulation (MRT) network in
Peninsular Malaysia and the TIMBALAN Datum for the Borneo Triangulation 1968 (BT68) network in
the Sabah and Sarawak states of East Malaysia.
3.3.1 Basic Horizontal Control Network
The horizontal control for mapping was established by connecting a mixed series of stations
(geodetic, primary, secondary and tertiary stations) by a combination of precise electronic distance
measuring techniques (Geodimeter) and first order astronomical observation to form the Malaysian
geodetic net covering Peninsular Malaysia. The stations in the network were then transformed into
the RSO coordinates system. This network is being replaced by the GDM2000 network, shown in Fig
2.3, which has been established using GPS satellite point positioning techniques to fit it into a global
geodetic framework. This network is termed Malaysia Primary Geodetic Network (PMPGN) and the
East Malaysia Primary Geodetic Network (EMPGN).
3.3.2 Basic Vertical Control Network
This control was established to provide orthometric (mean sea level) heights in the national height
system in the configuration of leveling networks. The datum for orthometric leveling in Peninsular
Malaysia is Bench mark No. B0169 Height 3.863 metres above Mean Sea Level (MSL) located at the
back of the tide gauge station on Warf No. 25 North Port, Port Klang. Hydrographic survey for
design of marine structures may require the heights to be tied to the Chart Datum used in Nautical
Charts. In such situations the Orthometric (Mean Sea Level) heights relative to the Chart Datum
available from the Hydrographic Division of the Royal Malaysia Navy has to be obtained. Fig 4.1
Survey Datum shows the relationship between the Chart Datum and Land Survey Datum.
3.4 REAL TIME KINEMATIC (RTK) SURVEY
The Geodesy Section, Department of Survey and Mapping Malaysia provide Real Time Kinematic
(RTK) Virtual Reference Station (VRS) technique which extends the use of RTK to the whole of
Peninsular Malaysia by the establishment of a network containing GPS reference stations over the
whole of Peninsular Malaysia. This service, which attracts a standard fee, is provided by the Malaysia
Real-Time Kinematic GPS Network System (MyRTnet), for users to conduct dynamic GPS Survey to
meet applications below:-
• Geomatics
• Deformation Monitoring
• Scientific Research
• Surveying
• Construction
• Navigation
• Mapping and GIS (Geographic Information System)
• Location Based Services
RTK VRS networking exploits the concept of all users sharing a common GPS coordinate control
framework and it significantly reduces systematic errors and extends the operating range with
improved accuracy requiring less time. It is surveying where users do not have to set-up their own
base stations
March 2009 3-3