Contents• Introduction to Surveying

• Setting and Leveling of Theodolite and Tilting Levels and parts of these instruments

• Measurement of Vertical Angle using Theodolite

• Measurement of Elevation between two points using Tilting Level

• Measurement of distance

• Measurement of area using Chain Surveying

Introduction to Surveying

Planning and DevelopmentBuilding Surveying

Quantity Surveying Mineral Surveying

Geodetic Surveying

Topographical Surveying

Hydrographic Surveying

Engineering Surveying

Land Surveying

Land Surveying

Engineering Surveying is used to

at the concept and design stage

Production of maps or plans

at the construction stage

Setting out and measurement

at the post construction stage

Measurement and monitoring

Surveying for all three aspects involves the measurement of three parameters :

Horizontal Distances Vertical Distances Angles

Horizontal Distances by:

Taping & Chaining Optical Methods Electronic Methods

Vertical Distances by

Taping Optical Methods Electronic Methods

Angles by:

Magnetic Compass Sextant Theodolite

A variety of methods and equipment can be used to measureeach of these parameters.

A

P

B

HorizontalAngle

Vertical Angle

Vertical Angle

(Elevation +ve)

(Depression -ve)

Measurement of Angles

A

P

B

HorizontalAngle Vertical Angle

Vertical Angle

I

Vertical Angle

A

P

B

I

Vertical Angle

Horizontal anglesare the same

ButVertical anglesvary withelevation (height)of instrument

THEODOLITE

(For Measuring Angles)

Setting up a TheodoliteEnsure that :-

• the tripod head is approximately level

• the tripod feet are firmly fixed in the ground

This should be done BEFORE removing the theodolite from its box.

Tripod Feet

Tripod Head

Tripod Height -middle toupperchest height

Tripod Head Horizontal

Feet - Duginto ground(if possible)

Setting up a Theodolite Place the theodolite on top of the tripod, and tighten the centring screw to clamp the theodolite centrally on the tripod head.

Hold Theodoliteby handle

Attach to tripodhead

Do not let goof handleuntil theodoliteis attached totripod.

TribrachLevellingScreworFoot Screw

Pond Bubble

Plate Bubble

Forapproximatelevelling

Foraccuratelevelling

Standing axis

Trunnionaxis

CollimationAxis

EyepieceFocus(For cross hairs)

InternalFocus(For sightingobject)

Levelling up a Theodolite

Carry out an approximate levelling. Using the pond bubble and by adjusting the length of TWO tripod LEGS, bring the pond bubble into the centre of the pond bubble tube.

The theodolite is ROUGHLY LEVELLED AND CENTERED over the station.

Setting up a Theodolite

Fine level the theodolite using the PLATE level bubble tube and foot SCREWS

Bubble follows LEFT THUMB

Position aPosition a

Position a) align the plate level bubble tube with two foot screws.

Centre the bubble by rotating the two foot screws in opposite directions. The bubble follows the LEFT thumb.

Plate Level Bubble Tube

Foot Screws

Required to move the bubble to the right

Bubble follows direction of left thumb

Both thumbs move in (or out)

Position a

• Position b) align the plate level bubble tube with the third foot screw. i.e. 900 from position a)

Centre the bubble by rotating the third foot screw (only)The bubble follows the LEFT thumb.

Using the thirdfootscrew only

Levelling up a Theodolite

Position b900 to position a

Bubble still follows LEFT THUMB

Position b900 to position a

Bubble still follows LEFT THUMB

Position b900 to position a

Position a

Repeat position a and b

Position b900 to position a

Vertical Circle - (for vertical angles)

Face LeftF/L

Transit Telescope

Rotate Theodolite

Face Right(F/R)

Some Typical Theodolite Diaphragms

This is FACE LEFT This is FACE RIGHT

Target

We need to superimpose the theodolite diaphragm over the target

This is how we should sight a target for

horizontal angle measurements.

This is how we should sight a target for

vertical angle measurements.

Example:

Theodolite - Instrument Errors

Plate Bubble Error . This is checked every time the theodolite is set up.

Non - Vertical Cross Hairs . Move the telescope up and down while sighting a well defined distant point.

Horizontal Collimation Error . Sight a well defined point and read the horizontal circle on F/L and F/R. The difference should be <40”

Vertical Collimation Error . Sight a well defined point and read the vertical circle on F/L and F/R. The difference should be <40”

Exp: 14 Measurement of Height of an Object, of which base is not accessible

OBSERVATIONS:

Bench Mark:Height of Instrument at First station (A) w.r.t. Bench Mark (x) = Height of Instrument at Second station (B) w.r.t. Bench Mark (y) = Horizontal distance between the two instrument stations (b) = Difference in the height of instrument at first and second stations (s) =

Instrument Station

Face Vertical Angle Reading Angle Remarks

Vernier C 0 ‘ ‘’

Vernier D0 ‘ ‘’

Mean 0 ‘ ‘’

A Left/Right

B Left/Right