1. Surveying Chain Surveying
Faculty of Applied Engineering and Urban Planning
Civil Engineering Department
Surveying
2nd Semester 2007/2008
Chain Surveying

2. Types of Distance Measurement Measurement Methods
Contents
Types of Distance Measurement
Measurement Methods
Direct (tapes)
Indirect: (EDM, Stadia)
Errors and Corrections for Tape Measurement
EDM

3. Introduction
One of the fundamentals of surveying is the need to measure distance. Distances are not necessarily linear, especially if they occur on the spherical earth. In the present subject we will deal with distances in Euclidean (geometric) space, which we can consider a straight line from one point or feature to another.

4. Common Methods for Measuring Distances
Pacing
Taping
Tachometry (required theodolite, and graduated rod)
EDM (Electronic Distance Measurement)

5. Equipment Used in Chain Surveying
Measurement of Lines
Chain
Tapes
Invar Tapes (more accurate, 65% steel, 35 Nicke)
Making Right Angles
Optical Prism
Others
Ranging Rods
Arrows
Pegs
Plumb bobs

6. Types of Distance Measurement

7. Types of Distance Measurement

8. Types of Distance Measurement

9. Examples: When use which
1. If you are intending to draw a map or area, horizontal distance and height difference (vertical distance) should be used to enable plan and height information to be drawn.
2. If you are to locate points such as a corner of a building or centre line of a road, slope distance and vertical distance are required to enable pigs be located at correct points on site (Layinging Out).

10. Methods of Measurement
Pacing
Accuracy 1 : 100
Taping
Accuracy 1 : 10,000
Electronic Distance Measurement (EDM)
Accuracy 1 : 10,000 to 1:100,000

11. Pacing Practical measure of distance.
Don't try to pace out one meter with every step. Walk casually over 100 m counting the number of steps. Work out the length of a casual step and use this instead.
Varies with uphill, downhill, and your age.
Low accuracy
No equipment needed

12. Taping (or chaining)
Chaining is applied to measurement with a steel tape or synthetic tape (plastic or fiberglass).
All standard in lengths
100 m, 50m, 30 m, 20 m.
It is fairly quick, easy and cheap, and hence is the most common form of distance measurement.
Unfortunately, Chaining is prone to errors and mistakes.
For high accuracy, steel tape should be used which is graduated in mm and calibrated under standard temp (20 degree) and tension (5kg). Be careful, easily break.
Synthetic tape is more flexible graduated in 10mm

13. Equipment Used in Chain Surveying

15. Some Taping Instruments
Measuring wheels
Tapes in lengths up to 100 ft

16. Taping Procedures ranging rods set up between points A and B
from A to B, set zero of tape at A
tape unwound towards B
A third range rod is “ranged” in at C
Tape straightened, held tight and read at rod C
C marked with a pin
for next bay, tape moved from A and zero set at C and so on

17. Accessories

18. Processes in Chain Surveying
Ranging and Measurement of Lines
Level Ground
Uniformly Sloping Ground
Uneven Ground

19. Level Ground
Rod
Rod A A1 A2 A3 A4 B

20. Stationing Along Baseline: stations At right angle: offset dist. 0+00
2+50
4+96

21. 21

22. Length AB = 4 x Full tape distance + 1 Short section22
Length AB = 4 x Full tape distance + 1 Short section
REMEMBER ! It works only on smooth ground or uniform slope surfaces

23. Example 23

24. Example How about this very uneven case or high accuracy is required?24

25. Example
Sag curve
Sag curve measurement is not common nowadays and is restricted to steel tape only. 25

26. Processes in Chain Surveying

27. Uniformly Sloping Ground

28. Uneven Ground

30. In Previous Ranging and Measurement of Lines Level Ground
Uniformly Sloping Ground
Clinometers
Abney Level
Uneven Ground

31. Homework
Solve Problems:
1.5, 1.6, 1.7
2.1, 2.2, 2.5

32. Lecture 5

33. Setting Out Right Angles
Method 1
Extend tape horizontally, swing it left and right , observe min. Reading
This method is primarily used on smooth ground where a free swing of tape is possible. C A B

34. Setting Out Right Angles
Method 2
With free end of tape, strike an arc to cross the line AB at points D & E. bisect DE at F.
Then angle CFE=90 C F A B D E

35. Setting Out Right Angles
Method 3
Run tape from C to D, bisect CD, with E as center and radius equal to ED, strike an arc to cross line AB at F, then DFC=90 C E D B F A

36. Setting Out Right Angles
Method 4
Using optical square with double prism
Prove Method 4 provided in the text book

37. Setting Out a Line at Right Angles
Method 1

38. Setting Out a Line at Right Angles
Method 2

39. Setting Out a Line at Right Angles
Method 3
5 m
3 m
4 m

40. Mapping Details Methods of Locating Ground Details Method of Ties:
a point is located by measuring two reasonable distance called ties between this point and two points on the chain line (a)
Method of Offsets :
a point is projected on he chain line and then the distance between the points and its projection (called offset) as well as the distance from the beginning point of the line to the projected point are measured. (b)

43. Choice of Chain Lines
Well conditioned triangles (Angles 30 – 120)

44. Choice of Chain Lines
As close as possible to the buildings

45. Choice of Chain Lines
At least two stations can be seen

46. Choice of Chain Lines
Minimum Number of Lines

47. Choice of Chain Lines
Provide check line possibility

48. Choice of Chain Lines
Avoid obstacles

49. Booking Details

50. Begin with fresh page
All measurement should be recorded
Proceed with booking from the bottom of the page to the top, the records should be recorded in the direction of chaining
All details must be sketched neatly and roughly to scale
All other chain lines which meet the chain line being measured should be recorded in appropriate place

52. Plotting the details

53. Booking the Measurements