1. Chemical Department. Guided by- prof D.M Prajapati. Prof. J. M. Jadav
Linear Measurements
Chemical Department.
Guided by- prof D.M Prajapati.
Prof. J. M. Jadav

2. Presented By Group no-7 Roll no. Leader- Singh Pritish 61
Dholariya Jigar 62
Sanghani Anuj 63
Chadmiya Keval 64
Aal Vinod 65
Patel Vikrant 51
Prasad Om Prakash

3. Index METHODS OF LINEAR MEASUREMNENT APPROXIMATE METHODS
CHAIN SURVEYING
CHAIN
TAPES
RANGING RODS
METHODS USED IN CHAIN SURVEYING
PRINCIPLE OF CHAIN SURVEYING
SELECTION OF CHAIN SURVEYING
OFFSETS
ERRORS
TYPES OF ERRORS
SOURCE OF ERRORS

4. Methods There are 3 methods of making linear measurements.
1- Direct Method.
2- Optical Method.
3- E.D.M Method.

5. Approximate Methods Pacing. Passometer. Pedometer. Odometer.
Speedometer.
Measuring Wheel.

6. pedometer
Speedometer
odometer
Measuring wheel
passometer

7. Instruments used in Chain Surveying
2) Tapes
3) Arrows
4) Ranging Rods and Offset Rod
5) Pegs
6) Plumb- bob

8. Types of Chains Metric chain Gunter’s chain or Surveyor’s chain
Engineer’s chain
Revenue chain
Steel band or Band chain

9. CHAINS

10. Taking measurements on chain
Metric chains are made in lengths 20m and 30m. Tallies are fixed at every five-meter length and brass rings are provided at every meter length except where tallies are attached.

11. Testing and Adjustment of chain
Closing up the joints of the rings if found to be opened out.
Reshaping the elongated rings.
Replacing damaged rings.
Removing one or more small rings.
Adjusting the links at the end.
Straightening the bent links.
Opening the joints of the rings.
Replacing one or more small circular rings by bigger ones.
Inserting new rings where necessary.
If chain is found to be too long
If chain is found to be too short

12. Types of Tapes Cloth or linen tape. Fibre tape. Metallic tape.
Steel tape.
Invar tape.

13. Tapes

14. Arrows Arrows are made of tempered steel wire of diameter 4mm.
One end of the arrow is bent into a ring of diameter 50mm and the other end is pointed.
Its overall length is 400mm.
An arrow is inserted into the ground after every chain measured on the ground.

15. Ranging Rods and Offset Rod
Ranging rods are 2 to 3 m in length.
Used for ranging some intermediate points on the survey line.
Painted with alternate bands of black and white or red and white colours.
With length of each equalising 20 cm.

16. Ranging rods

17. Pegs Made of timber or steel. Used to mark the position of stations.
Pegs are in length of 15 cm.

18. Plumb-Bob Used to transfer points on ground.
Used for fixing instrument exactly over the stations.

19. Principle of Chain Surveying
Triangulation is the principle.
In this area is divided into a number of triangles with the suitable sides.
The plan of the area can be easily drawn.
As a triangle is the only simple plane geometrical figure.

20. Terms related with Chain Surveying
1) Survey Stations: (a) Main stations (b) Subsidiary stations (c) tie stations 2) Main survey lines 3) Base line 4) Check line 5) Tie-line

21. Selection of Survey Stations
1) Survey lines should be minimum as far as possible and should be taken on fairly level ground. 2) should be intervisible. 3) Should form well conditioned triangles. 4) Should be located that tie lines, check lines, baseline etc. an be formed. 5) Should be selected within the boundary of the area to be surveyed.

22. Operations in Chain Surveying
Chaining
Ranging
Offsetting

23. Chaining on Level Ground
It involves following operations
Fixing the stations.
Unfolding the chain.
Ranging.
Measuring the distance.
Folding the chain.

24. Chaining on Sloping Ground
There are 2 methods:
Direct Method:
Also called as stepping. In this method, the distance is measured in small horizontal stretches. Say a1, a2 …an.
with suitable length of chain or tape.
finally the total horizontal distances are added to get the required distances

25. Chain surveying (“stepping”)w b x c y z

26. Chaining on sloping ground

27. Indirect Method
It involves calculation from directly measured lengths.
Method1:
Horizontal distance of the segment is calculated by knowing sloping length of the segment and angle of inclination of that with horizontal. The angle
The angle of the sloping surface with horizontal can be known by instrument called Abney’s Level.

28. Method2:
If the elevation difference between 2 terminals points and the sloping distance between 2 terminal points is known the horizontal distance D can be calculated as
D = (l²­h²)

29. Method3: Also called as hypotenusal allowance method
Instead of putting the end arrow at actual end of chain, it is put at some advanced distance and that point is considered as the end of one chain length

30. Ranging There are 2 methods: Direct ranging
Indirect ranging or reciprocal ranging.

31. Direct Ranging
When intermediate ranging rods are fixed on a straight line by direct observation from end stations, the process is known as direct ranging.
Direct ranging also can be done with a line ranger it consist of 2 right isosceles triangular prisms. Placed one above other.

32. Indirect or Reciprocal Ranging
When the end stations are not intervisible due to there being high ground between them, intermediate ranging rods are fixed on the line in an indirect way.
The method is known as indirect ranging or
reciprocal ranging.

33. Indirect Ranging

34. Offsetting There are 2 types of offsets: Perpendicular offsets:
the offsets which are taken perpendicular to the chain are termed as above.
2) Oblique offsets:
Oblique distance is always greater than perpendicular distance. All the offsets which are not taken at right angle to chain line are known as above.

35. Instruments for laying Offsets
Optical square.
Indian optical square.
Open cross staff.
Prism square.

36. Errors in Chaining There are 2 types Compensating errors
Cumulating errors

37. Sources of Errors in Chaining
Instrumental Errors
Natural errors
Personal errors

38. Errors due to Incorrect Chain
If chain is too long
If chain is too small
Measured distance will be less. Correction: positive
Measured distance will be more. Correction: negative

39. Tape corrections Corrections for absolute length
Corrections for temperature
Corrections for pull
Corrections for sag
Corrections for slope

40. Thank you