Surveying

Course: B.Sc. Agricultural

Subject :Fundamental of Soil, Water and Conservation engineering

Unit: 1

• Surveying:

It is the art of determining the relative positions of different

object on the surface of the earth by measuring the horizontal

distance between them and by preparing a map to any suitable

scale. Thus, in this process, the measurements are taken only

in the horizontal plane.

• Leveling:

Leveling is the art of determining the relative vertical distance

of different points on the surface of earth. Hence, in leveling,

the measurements are taken only in the vertical plane.

Objects of surveying:

• The primary object of survey is thepreparation of plan estate or buildings roads,railways, pipelines, canals, etc. Or to measurearea of field, state, nation.

• Object of geodetic surveying is to determineprecise positions on the surface of the earthof widely distant points.

• Types of Surveying [Classification]:

• Primary Classification or Primary Division :

Plane surveying and

Geodetic surveying

• Plane Surveying :

The shape of the earth is spherical. Thus the surfaceis obviously curved. But in plane surveying thecurvature of earth is not taken into account. This isbecause plane surveying is carried out over a smallarea, so the surface of the earth is considered as aplane. The degree of accuracy required in this type ofsurveying is completely low. Plane surveying is doneon an area of less than 250 km2.

• Geodetic surveying :

• In geodetic surveying the curvature of the earth istaken into consideration. It is extended over alarge area greater than 250 km2.

• The line joining any two points considered as acurved line. Very refined methods andinstruments are used in this type of surveying. Inthis method very high precision or accuracy isrequired.

• Secondary classification:

Survey can be classified on different bases.

• 1. Based on instrument:

- Chain Survey

- Compass survey

- Plane Table survey

- Theodolite survey

- Tacheometric Survey

- Photographic survey

• 2. Based on methods:

- Triangulation Survey

- Traverse Survey

• 3. Based on Objects:

- Geological survey

- Mine survey

- Archeological Survey

- Military survey

• 4. Based on nature of field

- Land Survey- Marine survey- Astronomical survey

• Again Land Survey is classified into following Classes:

• 1. Topographical Survey

To determine natural features of a country such as valleys,rivers and artificial features such as road, railways, etc.

• 2. Cadastral Survey:

To determine boundaries of field, estate

• 3. City survey:

To locate premises, streets, water supply and drainagesystems

• 4. Engineering survey:

To collect detailed data for the design for of projects involvingroads, railways, etc Engineering surveys are sub divided into:

1. Reconnaissance Survey

2. Preliminary Survey

3. Location Survey

Equipment used in Surveying1. Chain

The chain is composed of 100 or 150 pieces

of galvanized mild steel wire 4mm in

diameter called links.

The end of each link are bent into a loop and

connected together by means of three oval

rings.

The ends of the chain are provided with brass

handles for dragging the chain on the ground.

The length of link is the distance between the

centers of the two consecutive middle rings.

The end links includes the handles.

Metallic tags or indicators are fixed at

various distinctive of the chain to facilitate

quick reading.1

a. Metric surveying chains:

The chains are made in lengths of 20 and

30 meters.

To enable the reading of factious of a

chain, tallies (tags) are fixed at every five

meter length and small brass rings are

provided at every meter length.

To facilitate holding of the arrows in

position with the handle, a groove is cut on

the out side surface of the handle.

The handle joints are flexible.

The tallies used for marking the distances

in a metric chain are marked with letters

‘Me’ and ‘m’.2

b. Steel Band Chain:

It consists of a ribbon of steel with bras

handle at each end. It is 20 or 30 fit long and

16 mm wide. It is wound on an open steel

cross or on the metal reel in a closed case.

The graduations are etched as meters

decimeters, centimeters on one side and 0.2

m links on the other. Brass tallies are fixed at

every 5 m length of the band.

c. Gunter’s Chain:

It is 66 fit long and is divided into 100 links.

Each link is 0.66 ft long. It is very convenient

for measuring distance in miles and furlongs.

Also for measuring area and when the units

of area is an acre

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d. Revenue Chain

It is commonly used for measuring

fields in cadastral survey. It is 33 ft

long and divided into 16 links. Each

link is 2.0625 ft long.

e. Engineer’s chain:

It is 100 ft long and it is divided

into 100 links. Each link is 1 ft in a

length. Used in all Engineering

surveys.

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2. Arrows (chain pins):

They are also called as marking or

chaining pins and are used to mark

the end of chain during the process

of chaining.

They are made up of good quality

hardened and tempered steel wire of

4 mm in diameter. The arrows are

made 400 mm in length.

They are pointed at one end of

inserting in to the ground. The other

end is in to a ring.6

3. Tapes:

a. Cloth or Linen Tape

Used for taking subsidiary measurements, such

as offset. It is very light and handy. It is easily

affected by damp. If wet it shrinks. It stretches

easily and likely to twist.

b. Metric Woven Metallic Tape:

They are available in 2, 10, 30, and 50 meters.

The tape is made of yarn and metal wire. A metal

ring is attached to the outer end of tapes. The

length of the tape includes the metal ring. At

every centimeter a black line 8 to 10 mm in

height is drown. Every 5 centimeters is marked

with an arrow in black. Every decimeter and

meter is marked with a back line extending over

the full width of the tape/ the graduation marks at

every decimeter and meter are numbered with

black and red figures, respectively.

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c. Metric Steel Tape:

Tape is available in 1, 2, 10, 30,

and 50 meters. The tape is of steel

or stainless steel. The outer end is

provided with a ring. The length

of the tape includes the metal ring.

The tape is marked with a line at

every five millimeters,

centimeters, decimeters, and

meter.

Every decimeter and meter shall

be marked with Hindu Arabic

numerals in bold. When the

button release devised is pressed,

the tape automatically rewind in

to the case.

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d. Invar Tape:

For highest precision work the invar tape in

used. It is made of an alloy of steel and

nickel (36%).

It is 6 mm wide and may be obtained in

length of 30m and 100m. It is not calibrated

through its length but has terminal lines.

Each terminal division has ten 1 mm

division. It is very expensive.

e. Synthetic Tape:

The tapes are manufactured of glass fiber

having PVC coating. They are graduated

every 10 mm and figured every 100 mm.

Meter, figures are shown in red. They are

convenient for measuring shorts lengths.

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Instruments for marking stations:

1. Wooden Pegs:

These are used to mark the positions. They aremade of hard timber and tapered at one end.

They are usually, 2.5 cm square and 15 cm long.But in soft ground 40 to 60 cm long and 4 to 5cm square is suitable.

They should be driven in the ground with about4 cm lengths, projecting above the ground.

2. Ranging rods:

Used for making the positions of stations and forranging.

They are made of seasoned timber of teak, bluepine, deodar. They are circular or octagonal incross section of 3 cm diameter. Lower shoe is 15cm long.

They are made in two sizes as 2 meters and 3meters and are divided in to equal parts each 0.2m long.

They are painted alternatively black and whiteor red and white. Now a day instead of timber,mild steel hallo pipes are used.

Range pole

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3. Ranging Poles

Similar to the ranging rods but are

heavier, they vary in length from 4 m

to 6 m or more. Used in the case of

very long lines.

4. Offset Rod

Similar to the ranging rod, they are

usually 3 m long and is divided into

parts each 0.2 m length. Top is an

provided with an open ring for

puling or pushing the chain through a

hedge. It has two short narrow

vertical slots. It is used for aligning

short offsets.

Offset RodRanging Poles15 16

5. Laths

Useful for ranging long lines, also used over

uneven ground where the ranging rod is not visible

due to obstructions, they are light, cheap, being

white; they are easily visible at a great distance.

Unusually 1.0 m long

6. Whites

When the ranging rod is not available or

insufficient, whites are used. These are thin strip of

bamboo and 40 cm to 1 m in length. One end is

sharp and the other end is split for inserting pieces

of white papers. They are also useful for

temporary marking of counter points.

7. Plumb Bob

The plumb bob is required when measuring the

distance along slopes in order to transfer points to

the ground. It is also used for testing the verticality

of ranging poles.

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Uses of Surveying:

• To prepare a topographical map this shows the hills, valley, rivers, villages,

town, etc, of a country.

• To prepare a cadastral map showing the boundaries of fields houses, and other

properties.

• To prepare an engineering map to show details like roads, railways, canals, etc.

• To prepare military map showing roads and railways, communication with

different parts of country.

• To prepare contour map and to determine capacity of a reservoirs and ton find

the best possible route for roads, railways etc.

• To prepare archeological map including places where ancient relics exist.

• To prepare a geological map showing areas including underground resources.

Chain Survey

• Chain survey is the simplest method of surveying. In

this survey only measurements are taken in the field,

and the rest work, such as plotting calculation etc. are

done in the office.

• This is most suitable adapted to small plane areas with

very few details. If carefully done, it gives quite

accurate results.

• The necessary requirements for field work are chain,

tape, ranging rod, arrows and some time cross staff.

Survey Station:

Survey stations are of two kinds

- Main Stations

- Subsidiary or tie

Main Stations:

Main stations are the end of the lines, which command the boundaries of the survey,

and the lines joining the main stations re called the main survey line or the chain

lines.

Subsidiary or the tie stations:

Subsidiary or the tie stations are the point selected on the main survey lines, where

it is necessary to locate the interior detail such as fences, hedges, building etc.

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Base Lines:

It is main and longest line, which passes approximately through the centre

of the field. All the other measurements to show the details of the work are

taken with respect of this line.

Check Line:

A check line also termed as a proof line is a line joining the apex of a

triangle to some fixed points on any two sides of a triangle. A check line is

measured to check the accuracy of the framework. The length of a check

line, as measured on the ground should agree with its length on the plan.

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Offsets

• These are the lateral measurements from the

base line to fix the positions of the different

objects of the work with respect to base

line. These are generally set at right angle

offsets. It can also be drawn with the help

of a tape. There are two kinds of offsets:

• 1) Perpendicular offsets

The measurements are taken at right angle

to the survey line called perpendicular or

right angled offsets.

• 2) Oblique offsets.

The measurements which are not made at

right angles to the survey line are called

oblique offsets or tie line offsets. 21

Procedure in chain survey

1. Reconnaissance:

The preliminary inspection of the area to be surveyed is called

reconnaissance. The surveyor inspects the area to be surveyed, survey or

prepares index sketch or key plan.

2. Marking Station:

Surveyor fixes up the required no stations at places from where maximum

possible stations are possible.

3. Then he selects the way for passing the main line, which should be

horizontal and clean as possible and should pass approximately through the

centre of work.

4. Then ranging roads are fixed on the stations.

5. After fixing the stations, chaining could be started.

6. Make ranging wherever necessary.

7. Measure the change and offset.

8. Enter in the field the book.

Cross Staff Survey

• This type of survey is undertaken to locate boundaries of a field or a field

or plat and determinations of its area.

• Principle:

The principle of the survey is to divide the given area in to no of right

angled triangles and trapezoids and to calculate and plot the areas of

triangles and trapezoids.

• Instruments/Material Required:

Two Chains, arrows taps, ranging rods, cross-staff and drawing material

Procedure

Two chains are usually provided one for measuring distance along the

chain line and other for measuring the offsets.

The cross staff is used to set out the perpendicular directions for offsets.

In this survey, the base line runs through the center of the area, so that the

offsets are left or right side of base line are fairly equal.

To check accuracy length of the boundary lines may also be measured.

After the field work is over, the survey is plotted to a suitable scale.

Calculations of Field Area:

• By this method of survey, the field

as divided in to right angled

triangles and trapezoids are

calculated as under:

• Area of right -angled triangle = ½

base x Height.

• Area of trapezoid= sum of parallel

sides/2 x Height.

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Reference/Sources1.https://lh3.ggpht.com/eN01oZR9PxNPxpsDcr9gUZdGSUdrKiuiSM6uTY64ECJcAz1TzwZ03Up9CNHifvn5U6bl=s852.https://lh3.ggpht.com/9tUsVmdka8MeE5TQBNnJxhCik9XqSmuy2OwXq4ySVbnZbDufCvWRltLY_uJ_DuJwhm45=s953.https://lh4.ggpht.com/0afGESSNNYsmMmMv0loH0lVDvvyLKk9TetlZYwohJQn1inU_MrNSTxooTwcJC8rNizo2QYw=s1184.https://lh5.ggpht.com/xGo7qFS_xe99jBmWfVyx4wpDYVFSaK7aFT8dG1bwuk8lt404M3kHteFbBg2jprX8BPg7dtg=s1095. https://lh6.ggpht.com/KZR-0kE9ynzZpTPcZ5Tm1Gf7-5LkWs_YvUWe4csapsMxIdK9J-wUg9FX2zNAZR6ErIFmpA=s1136. https://lh6.ggpht.com/5_1Oqvwfg6P1u0HrPM-NSwMwfkklQsJ-vK8KJHA_sH03MToBGrpOyD_2sFBy1Es5DkfxSgM=s857. https://lh5.ggpht.com/eSch4M7mxb7IG-7aSArIvAfjonkDzrpMUAXVF1QcNUsKpCjsAYu6RNxJMTePz2JMaq_7bQ=s1278.https://lh3.ggpht.com/89hYheAiDqv0qR7mfGLsk39eZzDX0bI_iEpAdcNL9tBRA_UMv-kEZBKGXrS8u6jVvX2K=s859. https://lh4.ggpht.com/RBK5wB-

8WfdHm4QEo1MFeIVzD9MNYB8pzuYsTwBIk1tRroqGncPaFUpbyHPRCjCzk7oWOA=s8510. https://lh6.ggpht.com/3KB089IL-sNL7vByq4yw01aSe_b83wIvGMbEOiCZS9V0QvEXdfdpP-

kYEQD2S5QZSXMVug=s17011. https://lh3.ggpht.com/au8-70sN4qC4zzR2pN9V31mPy7eDOCCziYpJXOYfr9IbvGQzGVs2M1XZlIb8HlvYkndtSw=s10912. https://lh4.ggpht.com/Xlzt0Gnb7IYSfJuLlZHImrdKbKRw0U9unqb5A9qIPmy1AgqiHz-Y4DaKIsleCRQBO4pM_0Q=s10013. https://lh5.ggpht.com/SmNyiqF7EFp5UpA8cq3rXsCFTy9iNz0vmT8lutb_UW2d1RJ67cOBMlhjroTxwUjfkrCXQQ=s15614. https://lh4.ggpht.com/9IdAjwfXk5NXO3Mxzja-cOF80Bm3iY2XKJLsCRSHXwiFW1dpW6UKSFqrxw0lMJh-AYVuMg=s8515. https://lh6.ggpht.com/FwoZ0gcetDtRPRqJZ9CXjK9cLGT10P8ccMlyRJ2L2TDvMnY672beNQ6SbW4r3f3lMPnhPw=s8516. https://lh5.ggpht.com/tAjBWoJITFJ-gbI5exI2y8hZyRm5b134OgcujZma6suoHSTU3k0GgnHtgtZtMdAIv-MZvg=s8517. https://lh5.ggpht.com/WBZVAKVq183n8jC93lbQK4fHri3MFKte-6KjuFPG930ZcF7UIxj5xNWTRighBR_QPgucRA=s8518. https://lh5.ggpht.com/C7x33N0T2jtep5hKLMR7rGHFjKkC6Dt9Lj15E6Jvv15zya6RV7qeety4PByksrOh9ezP5A=s8519. https://lh4.ggpht.com/zgg7DK37XvrSyZHSCelix_FWW661DAKjqw00hLjIPiW2716qEEumiOCKu3T1A_Izkj-w=s17020. https://lh4.ggpht.com/4RiRKWY8MxCZl4h5bQRcZ_vnruopNr86yq6bFcUDlDdcCalFVVwKlSKUF3r0GN4PMrhu=s10221.https://lh4.ggpht.com/RIurXcgclWcPIZOjkudo-DoJw78NxwiLM8ZhQxITEks9JvB3xlIPJRq4IXk8COeXA8J5tAc=s8522. https://lh5.ggpht.com/tb3-E1StbD-UA2xhajIhLxI5IjjJZUodP6VHGkdFOjMkb9_ChG3svh8IjFirbPRF-Gf6=s85

Text book and web sources

- www.agriinfo.in

- ecourses.iasri.res.in

- Soil erosion and Conservation by R. P. Tripathiand H. P. Singh