Distance Measurements, Principle and Methods

Differents methods of distance measurement

1. Thematerialusedinthispresentationi.e.,pictures/graphs/text,etc.issolely
intendedforeducational/teachingpurpose,offeredfreeofcosttothestudentsfor
useunderspecialcircumstancesofOnlineEducationduetoCOVID-19Lockdown
situationandmayincludecopyrightedmaterial-theuseofwhichmaynothave
beenspecificallyauthorisedbyCopyrightOwners.It’sapplicationconstitutesFair
Useofanysuchcopyrightedmaterialasprovidedingloballyacceptedlawofmany
countries.Thecontentsofpresentationsareintendedonlyfortheattendeesofthe
classbeingconductedbythepresenter.
Fair Use Notice

2. CLO Description
Taxonomy
level
PLO
1DEMONSTRATE varioussurveying
equipmentandtechniquesusedfor
linearandangularmeasurementsand
forcomputationoftheareasand
volumes.
C3
1
(Engineering Knowledge)

3. Two principles of
measuring distance
1) It takes two points to form a line.
2) The shortest distance between two points is a straight line.

4. Distance
In surveying, the term “distance” has two uses.
Distance can also be used to
define the dimensions of an
object
The common use is to measure the
displacement (distance) between two
or more points.

5. Selecting The “Best” Method
◼Environment
◼Use of the data
◼Equipment available
◼Expertise of individuals
▪Personal preference
▪Topography
▪Client specifications
▪Regulations
▪Standard practice
The most important factor is the intended use of the data.
The best distance measuring method/device to use is
influenced by many factors.

6. Example-selecting best method/device
What unit of measure should be used to determine
the size of a wetland?
•Decimal feet?
•Foot?
•Miles?
•Acres?
What unit of measure should be used to
determine the size of a chemical spill?
What unit of measure should be used to record the location of a
site?

7. Distance Measuring Methods /devices
1.Pacing
2.Passometer
3.Pedometer
4.Odometer
5.Speedometer
6.Perambulator
7.Judging distance
8.Time measurement
9.Chaining
10.Stadia
11.Electronic Distance Measuring (EDM)
12.Global Positioning System (GPS)

8. ranging
rod at -A
Distance between A & B,m
ranging rod
at -B
GROUND

9. There are three methods for
making linear measurement :
➢DirectMethods
➢OpticalMethods
➢E.D.M.Methods

10. Direct Methods withoutinstruments
1)Judging thedistance
2)Pacing
3)Timeinterval

11. 2)Pacing
8

12. 2. Passometer

13. Direct Methods with
instruments
1)Chain
2)Odometer
3)Passometer
4)Pedometer
5)Speedometer

14. Odometer
An Odometer is a simple device which can be
attached to the wheel of a bicycle or any such
vehicle.
➢The odometer registers
the number of revolution
made by the wheel.
➢The distance covered is
equal to the product of
the number of
revolutions and the
perimeter of the wheel.

15. Types ofChain
Metric Chain :
It Consists of galvanized mild steel wire of 4mm diameter
known as link.
It is available in 20m, 30m, 50m
length which consists of 100 links.
Gunter’s Chain :
A 66 feet long chain consists of 100
links, each of 0.66 feet.
This chain is suitable for taking length in miles.
I mile = 8 furlongs and 1 Furlong = 660ft.

16. Types ofChain
Engineer’s Chain :
A 100 feet long chain consisting of 100 links each of 1 feet is
known as engineer’s chain.
This chain is used to measure length in feet and area in sq. yard.
Revenue Chain :
It is 33 feet long chain consisting of 16 links.
This chain is used for distance measurements in feet & inches
for smaller areas.

17. Types of Tapes
Cloth tape or Linen Tape :
they are woven linen and varnished to resist moisture.
They are generally 10m, 20m, 30m long and 12 to 15 mm wide.
Steel tape : It is made up with steel material and
commonly available in 20 m, 30m or 50m length.
It is graduated in m and cm.
Fiber tape :
These tapes are made of Glass Fiber.
These tapes don’t stretch and shrink due to
temperature. It is available in 20m, 30m and 50 m length.
25

18. Ranging Rods
Plumb Bob

19. Units of Measurements
◼Linear Measurement
◼One Foot = 12 inches
◼One Yard = 3 ft
◼One Furlong = 660 ft = 10 Gunter’s Chains
◼One Statute Mile = 5280 ft = 8 Furlong = 80 Gunter’s Chain
◼One Nautical Mile (in Marine Survey) = 6076 ft
◼One Meter = 3.28 ft
◼One Kilometre = 1000m
◼One Mile = 1.61 Km

20. Units of Measurements
◼Angular Measurement
◼Angle: direction of line wrtan otherline
◼Bearing: direction of line wrtmeridian e.g.North
◼Degrees, Minutes, Seconds
◼One Degree = 60 minutes
◼One Minute = 60 seconds
◼Radian

21. Units of Measurements
◼Measurement of Area (Length * Width)
◼One SqYard = 9 sqfeet
◼One Acre = 43560 Sqft = 10 SqGunter’s Chain
◼One Hectare = 10000 sqm
◼Measurement of Volume (Length * Width*Hight)
◼Cubic Feet ft
3
◼Cubic Meter m
3

22. Slope vs. Horizontal Distance
◼Distances can be measured in two ways:
1.Horizontal distance
2.Slope (surface) distance
•The horizontal distance between two points is the distance
between those points measured on a horizontal plane.
•The slope distance between two points is a distanced measured
along the surface of the earth.

24. Direct Method (Stepping Method):
➢Themethodconsistsinmeasuringthe
lineinshorthorizontallengthscalled
steps.

25. Indirect Method :
➢Therearefurtherthreetypesofindirect
methods.
✓ByusingClinometer/AbneyLevel
✓Byknowingthedifferenceoflevel
(elevation)betweentwopoints.

26. Using Clinometer / Abney Level
➢The distance along the slope is
measured and then the angle of slope
i.e. angle between the sloping ground
and the horizontal surface is found
with the help of Abney’s level.
➢ Knowing the sloping distance say “L”
and angle of slope say α horizontal
distance, D can be calculated by the
relation,
D =L cos α

27. D =L cos α

28. By knowing the difference of level (elevation)
between two points.
The distance along the slope is measured with chain and
the difference in elevation between the first and the end
stations is found with the help of any levelling instrument
Knowing the sloping distance I and the
difference in elevation h, the horizontal
distance, can be found out by the relation

31. = 20 in 100 = 1 in 5

32. h = 30m

38. Since the tape was 2.5 cm too short
e = 2.5 cm = 0.025 m
L’ = L -e