1. LINEAR MEASUREMENT-PART 1

2. INTRODUCTION Measurement of horizontal distance between two points.
Commonly used to set out the position of a point in construction work, etc.

7. METHOD OF LINEAR MEASUREMENT
Pacing
Odometer
Tapes
Chains
Tacheometry (stadia)
Electronic distance measurement (EDM)
Satellite systems and others.

8. TAPING
Taping is used for short distances and the length generally 10m, 30m, 50m, and 100m.
Linen or glass fibre tapes used for general use, where precision is not a prime consideration.
For more precise version, tapes are made of steel is preferred.
For high accuracy work, steel bands mounted in an open frame are used.

10. TAPING EQUIPMENT
RANGE POLE
TAPING PINS
TAPES
PLUMB BOBS

11. TAPING PROCEDURES Site inspection and setup Lining in Applying tension
Plumbing
Marking tape length
Reading the tape
Recording the distance

12. SITE INSPECTION AND SETUP
A preliminary investigation is to identify and locate initial starting and fixed points and to map out the measurements strategy.
Range poles may be placed to help define the measurement line.
Field notes should be taken for later reference (e.g. date, weather, temperature, potential obstructions, topography etc.)

13. LINING IN
Using range poles, line measured should be marked at both ends and at intermediate points where necessary (to ensured unobstructed sight lines).
Required at least 2 person (forward and rear tape person).The rear tape person holds the tape roll at the starting point; while the forward tape person pulls the tape to the end point of required distance or until the entire tape length has been deployed.
The rear and forward tape person should always remain within sight of each other. If the sight line is obstructed, it is necessary to “break” the measurement distance into shorter lengths to bypass the obstruction.

14. APPLYING TENSION
The rear tape person should holding 100-ft end of a tape over the first (rear) point lines in while the forward tape person holding the zero end of the tape.
For an accurate results, the tape must be straight and the two ends held at the same elevation. Tension apply generally between 10 and 25 lb.

15. PLUMBING
Weeds, brush, obstacles and surface irregularities may make it undesirable to lay a tape on the ground.
Thus, the tape is held above ground level in horizontal position.
Each end point of a measurement is marked by placing the plumb-bob string over the tape and securing it with one thumb .
A plumb-bob is used to locate the measurement point on the tape vertically above a fixed marker, or to place taping pins to mark tape lengths

16. MARKING TAPE LENGTHS
When line in properly, tension has been applied and the real tape person is over the point stick is called out.
The forward tape person then places a pin exactly opposite the zero mark of the tape and calls stuck.

17. READING THE TAPE
There are two commons styles of graduation on 100-ft surveyor ‘s tapes.
Common type of tape has a total graduated length of 101 ft.
Another type in practice has total graduated length of 100 ft

18. RECORDING THE DISTANCE
Accurate field work may be spoiled by careless recording.
Although taping procedure may appear to be relatively simple, high precision is difficult to achieve especially for beginners.
Taping is a skill that can be best taught and learned by field demonstration and practice.

19. EXAMPLE..

20. INCORRECT LENGTH OF TAPE
Incorrect length of tape can be one of the most important errors.
The tape is not of ‘true’ length.
Error caused by incorrect tape length occurs each time the tape is used.

22. TEMPERATURE OTHER THAN STANDARD
Error caused by temperature change may be practically eliminate by either
Measure temperature and making correction
Using Invar tape (Nickel-steel alloy tapes) *usually used primarily in high precision taping.

24. INCONSISTENT PULL (TENSION)
When a steel tape is pulled with a tension greater than its standard pull, the tape will stretch and become longer than its standard length.
Errors resulting from incorrect tension can be eliminated by
Using the spring balance to measure and maintain the standard pull
Applying a pull other than standard and making correction

26. UNEVEN OR SLOPING GROUND
In taping on uneven or sloping ground, it is standard practice to hold the tape horizontally and use a plumbob.
Wind exaggerates this problem and may make accurate work imposibble.
On steeper slope, where the length cannot be held horizontally without plumbing from above shoulder level, shorter distances are measured and accumulated to total.

27. S1
required (horizontal) distance A S2
AB= S1+S2+S3 S3

29. SAG
Because of sag, the horizontal distance is less than the graduated distance between tape ends.
Can be reduced by applying greater tension but not eliminated unless the tape is supported throughout.
Eliminated by
Supporting the tape at short intervals or throughout
Computing the sag correction

31. CATENARY TAPING measured distance required distance

32. TAPE MUST BE STRAIGHT distance distance obstruction required measured
measured distance ≠ required distance

33. Example 1:
A road centerline gradient falls from station0+00 with an elevation of m to station 1+50 at rate -2.5% . What is the elevation at station 1+50?

34. Example 2:
A road run from a station 1+00 with an elevation of m to station m with an elevation of m. What is the slope of grade line?

35. Example 3:
A measurements was recorded as m with a 30m-tape that was only m under standard conditions. What is the corrected measurements?

36. Example 4:
A 30-m tape is used with a 100-N force, instead of the standard tension of 50N. If the cross-sectional area of the tape is 0.02 cm2, what is the tension error per tape length?

38. TAPING Taping must always be STRAIGHT Tape must not be twisted
Use CHAINING ARROWS for intermediate points
Tape horizontally if possible
Tape on the ground if possible
Slope taping needs to be reduced
Catenary taping requires correction

39. Mistakes Taping
Measuring from wrong marker
Reading the tape incorrectly or transporting figures Recording the value incorrectly in the notes.
Making arithmetic mistakes in some of dimensions and error mistakes. how to avoid this mistake?