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

Chapter 1 GEOMATICS AND LAND SURVEY SERVICES
KNOWN
STATIONS
A. CLOSED LOOP TRAVERSE
KNOWN
STATIONS
KNOWN
STATIONS
B. CLOSED CONNECTION TRAVERSE
KNOWN
STATIONS
C. OPEN TRAVERSE
Figure 1.1 Types of Traverse
1.5.3 Revision
Whenever a survey is initiated, the methods and scope of works employed by the surveyor should be
formulated in the light of the following requirements:
a. The requirements of the team of professionals who will be designing and subsequently
implementing the project for the Department of Irrigation and Drainage. Checks should also
be made that the requirement of another Department is taken into consideration e.g. the
Ministry of Agriculture, Public Works Department or the Land Office resettlement plan.
b. It is important that a survey work done for one purpose may at some future date be used
for a different purpose. The department concerned should anticipate this and consider
whether, by some minor adjustment, the scope of works can be made more generally useful
than the immediate needs.
c. It is important that all leveling or height control and connection work which include the
establishment of hydrological stations are tied to Survey and Mapping Department Bench
Marks (BM) and that Temporary Bench Marks (TBM) are established on permanent features
at strategic locations within the proposed scheme for future use.
d. The field surveyor’s first task is to establish the horizontal and vertical control frameworks
which are tied to the Survey Department Horizontal Datum for position and to the Land
Survey Vertical Datum or the Chart Datum at the respective tide gauge stations for levels or
TBM. Fitted within this framework are the supplementary control such as the DID proposed
baseline, check line or secondary gridline where appropriate to pick up details of features
and points contained in the Term of Reference (TOR)
March 2009 1-3