Report Levelling

2050 Words Dec 26th, 2010 9 Pages
LEVELLING (Two Peg Test)
Introduction
Two Peg test need to carry out before we start the levelling job to ensure the instrument in good condition 1.0 Aim
Peg Test is a surveying operation carried out to determine if the leveling bubble (bubble axis) and telescope line-of-sight ( line of collimation )are parallel.

2.0 Equipments 3.1 Level and Tripod ( 1 set) 3.2 Staff ( 2 sets ) 3.3 Staff bubble (2 sets ) 3.4 Tape ( 1 set )

3.0 Procedures 4.5 Each group will be required to perform a peg test to check the instrument. 4.6 All person in the group should recorded the result of the peg test in their own field book. 4.7 Two point some 60 m apart are set out and marked the ground (with
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The first reading from any instrument position is termed back sight (BS). Readings which are neither the first nor the last from the instrument station are termed intermediates (IS). The last reading from an instrument position is termed a foresight (FS).The concept of levelling based on the horizontal line through the level with level line through the points on the surface of the earth.

Example diagram measuring levelling position:

INSTRUMENT

Equipments levelling (two peg tests): * Level and tripod (1 set)

* Staff (2 sets)

* Staff bubbles (2 sets)

* Tape (1 sets)

Equipments levelling (establish temporary benchmark (TBM)) * Level and tripod (1 set) * Staff (2 sets) * Staff bubbles (2 sets)

Fundamental two types of equipment:

(i) Level
(ii) Levelling rod

Types of level:

(i) Dumpy & Wye levels
(ii) Tilting levels
(iii) Automatic level (usual used)
(iv) Digital levels
(v) Electronic laser levels

Levelling rod/levelling staff: Levelling rod is manufactured from wood, metal, or fibreglass and is graduated in meters or feet. The metric rod can usually be directly only to 0.01 m.

FIELD PROCEDURES

Surveying work must be started from a Bench Mark (BM @ TBM).
All the observation must started from the back sight observation to fore sight observation.
The distance

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