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

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Chapter 4 REFERENCES ON GEOMATICS AND LAND SURVEY SERVICES<br />

TIDAL REFERENCE FOR PULAU SIBU<br />

31.847 m (BM S1150)<br />

Above L.S.D<br />

00m (L.S.D)/(M.S.L)<br />

32.547m (BM S1150)<br />

Above Chart Datum<br />

1.700m<br />

NAUTICAL OR ADMIRALTY CHART DATUM<br />

-1.700m (Chart Datum)<br />

00 (Chart Datum)<br />

Chart Datum is 1.700M below L<strong>and</strong> Survey Datum (L.S.D) at<br />

Survey Department Bench Mark (BM S1150)<br />

Figure 4.1 Survey Datum<br />

4.5 LEVELING BENCH MARKS (BM) OR MONUMENTATION (JADUAL 2001 ITEM<br />

1.7)<br />

A Bench Mark is a relatively permanent object natural or artificial, bearing a marked point normally a<br />

brass bolt set in concrete with a bench mark number inscribed. The elevation or the height of the<br />

point above or below the L<strong>and</strong> Survey Datum (LSD) or National Geodetic Vertical Datum (NGVD) has<br />

to be purchased from Geodesy Section, Department of Survey <strong>and</strong> Mapping. Establishment of<br />

subsidiary marks or monuments related to the Department of Survey <strong>and</strong> Mapping Bench Marks by<br />

conducting Height Control <strong>and</strong> Connection Surveys are known as:-<br />

a. Temporary Bench Marks (TBM)<br />

• Plan of a TBM marker on Normal surface is shown in Appendix 4A-6.<br />

• Plan of a TBM marker on hard surface is shown in Appendix 4A-7.<br />

b. Intersection Point Marks (IP)<br />

c. Reference Marks (RM)<br />

March 2009 4-3

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