8.3.5 MMBW Datum
Prior to the introduction of Australian Height Datum and the conversion of levels to metres, the MMBW Datum as it was called, was the only one widely used
in the metropolitan area. Over the years, some 3000 bench marks were
established to the old datum throughout the metropolitan area.
WARNING: Levels purporting to be on this datum
should always be verified as many were deduced from
contours or surface levels without a bench mark check.
Source: Survey Practice Handbook – Part 2: Survey Procedures – Levelling Section 8
Height Determination
Area A: Tables may be directly applied to obtain A.H.D. Values
adjustment: Subtract 1.72 feet (x 0.3048)
Area B: Values derived from tables must be reduced by 0.06m to obtain A.H.D. values
adjustment: Subtract 1.92 feet (x 0.3048)