plane table suveying

1. SURVEYING
PREPARED BY:
140010106003 BARSIYA CHAITANYA A.
140010106014 HADIYA SANKET M.
140010106017 KEVADIYA MANTHAN J.
140010106024 MISTRY NEEL R.
PLANE TABLE ACCESSORIES
&
SETTING UP OF THE PLANE
TABLE

2. EQIPMENTS & ACCESSORIES FOR PLANE TABLE
 Plane table is a graphical method of survey in which the field observations and
plotting are done simultaneously.
 The following instruments are used in plane table.
 EQUIPMENTS ACCESSORIES
1. Plane table 1. Trough compass
2. Tripod 2. spirit level
3. Alidade 3. U-fork level
4. Water proof cover
5. Drawing paper
6. Pins
7. Drawing accessories

3. EQUIPMENTS FOR PLANE TABLE
PLANE TABLE
1. It is made from well-seasoned wood
with its upper surface exactly plane.
2. It is normally rectangular in shape with
size 75cm x 60cm.
3. It is mounted on a tripod and clamps
are provided to fix it in any direction.
4. Types of plane table
1) simple plane table
2) Johnson plane table
3) coast survey plane table

4. EQUIPMENTS FOR PLANE TABLE
TRIPOD
1. The plane table is mounted on a
tripod.
2. The tripod is generally of open frame
type, combining rigidity with
lightness.
3. The tripod may be made to fold for
convenience of transportation.
4. Tripod is provided with three foot
screw at its top for levelling of the
pane table.

5. EQUIPMENTS FOR PLANE TABLE
ALIDADE
 The alidade is useful for establishing
a line of sight.
 There are two types of alidade
1. Simple alidade
2. Telescopic alidade

6. EQUIPMENTS FOR PLANE TABLE
Smilpe Alidade
 It is for ordinary work.
 It is generally consists of a gun metal or
wooden rule with two vertical vanes at the
ends.
 To draw the rays, one of the edge of alidade is
bevelled and this perfectly smooth working
edge is known as the fiducial edge. The
fiducial edge is graduated to facilitate the
plotting od distance to a scale.

7. EQUIPMENTS FOR PLANE TABLE
Telescopic alidade
 The telescopic alidade is used when it is
required to take inclined sights.
 It essentially consists of a small telescope with a
level tube and graduated arc mounted on
horizontal axis.
 It gives higher accuracy and more range of
sights.

8. ACCESSORIES FOR PLANE TABLE
Trough compass
 The trough compass is required for
drawing the line showing magnetic on
the paper. It is used to orient the table
to the magnetic meridian.
 When the freely suspended needle
shows 0°- 0° readings at each end, a
line is drawn on the drawing paper
which represent the magnetic North.

9. ACCESSORIES FOR PLANE TABLE
Spirit level
 A spirit level is used for
ascertaining if the table is
properly level.
 The table is levelled by placing
the level on the level on the
board in two positions at right
angles and getting the bubble
central in both positions.

10. ACCESSORIES FOR PLANE TABLE
U-Fork with plumb bob
 U-fork with plumb bob is used
for centring the table the point
or station occupied by the
plane table when the plotted
position of that when the
plotted known on the sheet.
 Also, in the beginning of the
work, it is used for transferring
the ground point on the sheet.

11. ACCESSORIES FOR PLANE TABLE
Water Proof cover
 An Umbrella is used to protect
the drawing paper from rain.
Drawing Paper
 Drawing paper is used for
plotting the ground details.

12. SETTING UP THE PLANE TABLE
 The following processes are involved in setting up the plane table over the
station.
1. Fixing the plane table on the tripod
2. Levelling
3. Centering
4. Marking the north line
5. Orientation

13. SETTING UP THE PLANE TABLE
1. Fixing the plane table on the tripod:
 The legs of tripod should be spread be well apart and firmly fixed into the
ground.
 The table should be set up at a convenient height for working on the board , say
about 1.2 m , depending upon the height of the surveyor.

14. SETTING UP THE PLANE TABLE
2. Levelling:
 In a simple plane table , levelling is done by moving the tripod legs. The levelling
is judged by eye.
 For levelling the plane table , ordinary spirit level may be used.
 The plane table is levelled by placing the level on the board in two positions at
right angles and getting the bubble central in both directions.

15. SETTING UP THE PLANE TABLE
3. Centering
 The process of setting up the plane table on the plotted position of the ground
station exactly over the station, is know as centering. It is done by U-fork and
plumb bob.
 The drawing sheet is fixed on the table. It is conventional to the table. It it is
conventional to use capital letters A,B,C etc. for ground stations and the lower
case letters a,b,c etc. for the plotted points corresponding to the ground stations.
 The table is turned clockwise or anticlockwise or the legs are slight adjusted so
that the plumb bob is centred over the ground station.

16. SETTING UP THE PLANE TABLE
4. Orientation
 The process by which the position occupied by the board at various survey
station are kept parallel is know as the orientation. Thus , when a plane table is
properly oriented, the line on the board are parallel to the lines on the board are
parallel to the line on the ground which they represent.
 There are two method of orientation
1. by magnetic needle
2. by back sighting

17. SETTING UP THE PLANE TABLE
1. By magnetic needle :
 In this method, the magnetic north is drawn on paper at a particular station.
 At the next station, the trough compass is placed along the end of magnetic
north and the opposite to zero of the scale. The board is then fixed in position
clamps.
 This method is inaccurate in the sense the results are likely to be affected by the
local attraction.

18. SETTING UP THE PLANE TABLE
2. By back sighting
 A= first survey station
 B = second survey station

19. SETTING UP THE PLANE TABLE
 Suppose a line is drawn from station A on paper as ab, representing line AB on
ground.
 The table centred and levelled at station B and then the alidade is placed the line
ba.
 The table is turned till the line of sight bisects the ranging rod at A.
 The board is clamped in this in this position.
 This method is better than the previous one and it gives perfect orientation.