1. What is “Leveling”
Levelling is the process by which differences in height between two or more points can be determined. Its purpose may be to provide heights or contours on a plan, to provide data for road cross-sections or volumes of earthworks, or to provide a level or inclined surface in the setting out of construction works

3. Definitions
Datum - This is an arbitrary level surface to which the heights of all points are referred. This may be the National Datum (Australian Height Datum) or local datum point established on a construction site.

6. Mean Sea Level(MSL)
Mean sea level (MSL) is the average (mean) height of the sea between High and Low tides

7. Definitions
Reduced Level (RL) – A distance recorded as a Height Above or Below the DATUM. This height is in metres

11. Definitions
A benchmark in every-day language is a point of reference for a measurement. In surveying a benchmark is specifically any permanent marker placed by a surveyor with a precisely known vertical elevation (but not necessarily a precisely known horizontal location). Designed to be used for many projects.

12. Height Benchmark

13. Other Types of Bench Marks

14. Horizontal Control

16. Definitions
A Temporary benchmark (TBM) Benchmark usually placed for a particular project. Not designed to be a reference for other projects or for long term use

17. Australian Height Datum (AHD)
The Australian Height Datum is a theoretical reference surface (datum) for altitude measurement in Australia.
In 1971 the mean sea level for was assigned the value of zero on the Australian Height Datum at thirty tide gauges around the coast of the Australian continent.
The resulting datum surface, has been termed the Australian Height Datum (AHD) and was adopted as the datum to which all vertical control for mapping (and other surveying functions) is to be referred.

20. Tools For Leveling
Spirit Level - or bubble level is an instrument designed to indicate whether a surface is level or plumb
                                                

21. Spirit Level Varying Lengths 300mm to 2400mm Can also be magnetic
Quality of Levels vary markedly

22. Non Magnetic
Magnetic
Digital Levels
Masonry
Torpedoes

23. Tools For Leveling
A line level is a level designed to hang on a builders string line. The body of the level incorporates small hooks to allow it to attach and hang from the string line. The body is lightweight, so as not to weigh down the string line, it is also small in size as the string line in effect becomes the body; when the level is hung in the centre of the string, each leg of the string line extends the levels plane
                                                

25. Boning Rods
Boning rods are T-shaped and made of wood. Their height is normally 100 cm and the cross-lath is 50 cm x 10 cm. The bottom part is sometimes reinforced with metal
It is important that all boning rods have exactly the same height (100 cm) and while working with the boning rods, the sun should be kept in the back, as it would otherwise be difficult to see them. Usually a total of 3 or 4 boning rods is required.

26. Boning Rods

27. Water Level Transparent flexible tube of about 14 m long.
The tube is filled with water so that the water level is about 1 m high in each of the tube ends. It is essential that no air bubbles be trapped in the tube. Air bubbles can be removed by tapping the tube with the finger.
Wherever the two staffs are set, the free water surfaces in the tube ends have the same level

28. Water Level

29. Transit Levels Very Accurate Very Difficult to Set Up
Can also set grades
Works similar to a plumbers pipe level

30. Definition
Line of Collimation – Imaginary line that passes through leveling instrument at Cross Hairs

31. Automatic Level
The Automatic Level is an easy to use surveying Instrument
Instrument needs only to be setup level within its circular level bubble
Has a damping compensator which adjsuts line of colimation
Generally accurate to +/- 2mm

32. Automatic Level Base Plate Horizontal Circle Eyepiece Circular Bubble
Sighting Pointer
Objective Lens
Focusing Knob
Fine Motion Drive
Footscrew
Bubble Mirror

33. The Compensator Prism suspended by wires
Prism moves to keep line of collimation level within its design (+/-) 2mm etc
Prism is magnetically dampened
Suspended Prism may go out adjustment

34. Laser Level Has a compensator similar to Automatic Level
Radiates a Laser Beam 360 through line of collimation
Laser is then picked by a receiver to indicate line of collimation
Some lasers are self leveling

35. Errors particular to Lasers
Reflections from other glass objects ie car windscreens
Rotating Beacons
Lasers being used at other sites, typically lasers have range of 300m

36. Definition
Backsight – A sight taken to a benchmark or temporary benchmark.
Typically the first sight taken after setting the instrument up

37. Definition
Foresight – This the last sight taken before the instrument is moved during a traverse

38. Definition
Intermediate Site – These are the sights taken at nominated position, known as stations. The sights are then converted to reduced levels

39. Leveling Errors
There are a large number of potential sources of errors in leveling. Many of these are only significant for precise leveling over long distances. For the short segments of leveling that will occur in connecting a TGBM to nearby benchmarks there are only four worth mentioning: 
·        Collimation Error
·        Error due to Earth Curvature
·        Error due to Parallax Error
·        Error due to Refraction

40. Collimation Error
The Automatic Prism compensator goes out of alignment.
The level provides readings outside of its specification

41. Collimation Error

42. Parallax Error
When using an optical instrument — both the image and cross hairs can be focused- if either is imprecisely focused, the cross hairs will appear to move with respect to the object focused, if one moves one's head horizontally in front of the eyepiece.

43. Parallax Error

44. Correction of Parallax Error
Adjust Focus of lens to infinity
Focus of Cross Hairs to a sharp setting Note every users parallax focus is different
Refocus on Target and check for parallax

45. Curvature of the Earth
Due to the curvature of the Earth, the line of sight at the instrument will deviate from a horizontal line as one moves away from the level

46. Correction of Curvature Error
For a sight length of 100m the effect is only 1mm.
Keep Sight lengths under 50m
the effect is eliminated by using equal sight lengths for fore- and backsights.

47. Refraction
The variable density of the Earth's atmosphere causes a bending of the ray from the staff to the level.
May also be caused by heat emitted by plant
May be caused by heat haze

48. Leveling Staffs
The staff is simply a large ruler, available in lengths of 3, 4 or 5 metres and usually made of aluminium with telescopic sections

49. Reading the E Staff Color Alternates every metre
Each graduation is 100mm
Each “E” is 50mm
Metre height & 1/10m is located in lower 50mm
Each Part of the E is 10mm
Millimeters are interpolated
Staff is read to the millimeter

50. Reading an “E-face” staff
0.339
0.33
0.3

51. Staff Reading Excercise
Staff Leveling Tutorial
On Line Excercises found at

52. Reading Staffs It is important to hold staff plumb
Use slow rocking technique
Use vertical line in level to keep plumb

53. Removing Staff Reading Errors
Step 2 Staff Slowly Tilted away from Instrument. When Vertical lowest reading will be reading recorded
Step 1 Staff Slowly Leant Towards Instrument
Step 3 Staff Slowly Tilted away from instrument. Once past vertical readings will increase
Important Note – The person using the instrument keeps the staff vertical by use of the Vertical line in the instrument.

54. Stadia Reduction The middle line is the line of Collimation
The Short lines are called stadia lines
Usually Stadia multiplier is 100

55. Stadia Reduction Upper stadia = 3.040 Lower stadia = 2.946
Stadia difference = 0.094
Distance to staff = x 100 = 9.4 metres

56. Stadia Reduction Method used for Measuring Distance
Not Very Accurate (1mmVrt=100Hz)
Not to be used to setting out
Used with Horizontal Circle to make contour drawings

57. Definition - Traverse A method of transferring a benchmark
Can be Open or Closed
Open Traverse begins at a point of known position and ends at a station whose position is unknown (This traverse type should be avoided)
Closed Traverse begins and ends at the same point whose position is known.

58. Schematic of a Traverse

59. Traversing Exercise

60. Step 1
Set up the instrument where the benchmark can be viewed within correct parameters and a reasonable number of sights can be viewed. This location is identified as L1 circled in red

61. Step 2

62. Step 3

63. Step 4

64. Step 5

65. Step 6

66. Step 7

67. Step 8

68. Step 9 Tally Backsight & Foresight columns

69. Definition - Misclose
Definition – Misclose- is when closing of a traverse due to errors in readings and instrument limitations there is a discrepancy.
The allowable discrepancy is (12 x square root of traverse in kilometres)

70. Traverse Misclose Traverse Length = 190 metres
Allowable Misclose = 12 x SQRT(0.190) = 12 x = mm

71. Step 10a Calculate Rise & Falls

72. Step 10b Tally Backsight & Foresight columns Note – Misclose should equal Backsight/Foresight Misclose

73. Step 11

74. Traverse No. 2

75. Traverse No. 2

76. Traverse No. 3

77. Traverse No. 3

78. Field Exercise

83. Height of Collimation Method

84. Height of Collimation Method
It is more convenient for “Area Levelling” and can become cumbersome on long traverses.
It is also an easier method for “On the Fly Levelling”
Also Known as Instrument Height Method

85. Traversing Exercise Height of Collimation Method

86. Step 1
Set up the instrument where the benchmark can be viewed within correct parameters and a reasonable number of sights can be viewed. This location is identified as L1 circled in red

87. Step 2

88. Step 3

89. Step 4

90. Step 5

91. Step 6

92. Step 7

93. Step 8

94. Step 9 Tally Backsight & Foresight columns

95. Definition - Misclose
Definition – Misclose- is when closing of a traverse due to errors in readings and instrument limitations there is a discrepancy.
The allowable discrepancy is (12 x square root of traverse in kilometres)

96. Traverse Misclose Traverse Length = 190 metres
Allowable Misclose = 12 x SQRT(0.190) = 12 x = mm

97. Step 10