Guide to Surveying and Levelling

Principles of Chain Surveying or Linear Surveying | Civil Engineering

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Chain Surveying or Linear Surveying | Surveying and Levelling

It is the method of land surveying in which only linear measurements are made.

Chain surveying requires chain, tape and ranging rods.

Chain surveying is not suitable for large areas having many details.

(The term “details” means a natural or manmade features at or near the ground surface).

Chain Surveying
Chain Surveying

It consists of the following:

Hard details

Hard details include buildings, roads, walls etc.

Soft Details

Soft details include river, vegetation, trees etc.

Overhead details

Overhead details include power and telephone lines.

Underground details

Underground details include survey of water mains, sewer etc.

Principles of Chain Survey

A triangle is a simple figure which can be plotted from the lengths of three sides even if the angles are not known.

In chain survey, the area to be surveyed is divided into a framework consisting of triangles.

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Height of Instrument Method | Surveying and Levelling

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Height of the Instrument Method

The following readings were observed with a levelling instrument, the instrument was shifted after 5th and 11th reading.

0.585, 1.010, 1.735, 3.295, 3.775(5th)

0.350, 1.300, 1.795, 2.575, 3.375

3.895 (11th), 1.735, 0.635, 1.605

Determine the RLs of various points if the reduced level (RL) of a point on which the first reading was taken is 136.440 gives the height of collimation method and applies the check.

Station BS IS FS HI RL Remarks
123

4

5

 0.585 

 

0.350

 1.0101.735

3.295

  

 

3.775

 137.025 

 

133.600

 136.440136.015135.290

133.730

133.250

 RL of I point 

 

CPI
678

9

10

  

 

1.735

 1.3001.7952.575

3.375

  

 

3.895

  

 

131.440

 132.300

131.805

131.025

130.225

129.705

 CP II
1112 0.635 1.605 130.805

129.835
Sum of BS=2.670 Sum of FS =9.275

HL = RL + BS

= 136.440 + 0.585

= 137.025

RL = HL – IS

Check

(Summation of BS)-(Summation of FS) = Last RL – First RL

2.670 – 9.275 = 129.835 – 136.440

-6.605 = -6.605

Conventional Signs or Symbols | Surveying and Levelling

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Conventional Signs and Symbols used in Surveying

Here are a few important Conventional Signs and symbols useful in the field of Surveying:

  1. Marsh or Swarm
  2. House
  3. Embankment
  4. Cutting
  5. Single Line Railway
  6. Double Line Railway
  7. Lake or Pond
  8. Road
  9. Railway Bridge
  10. Road Bridge
  11. River
  12. Fence
Marsh or Swarm
Marsh or Swarm
House
House

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Different Methods for the Calculation of Areas in Surveying

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Different methods for the calculation of Areas in the field of Surveying

In this article, we will list out different methods to calculate the areas in Surveying and also study each of the method in depth… We will also explain each method with a suitable example for your better understanding…

Here are the five important rules (Methods) used for the calculation of areas in Surveying:

  1. Midpoint ordinate rule
  2. Average ordinate rule
  3. Simpson’s rule
  4. Trapezoidal rule
  5. Graphical rule

We will now move on with our discussion on the first rule “Midpoint ordinate rule” with a suitable example.

Midpoint-ordinate rule

The rule states that if the sum of all the ordinates taken at midpoints of each division multiplied by the length of the base line having the ordinates (9 divided by number of equal parts).

Midpoint ordinate rule | Method for calculating area in Surveying
Midpoint ordinate rule | Method for calculating area in Surveying

In this, base line AB is divided into equal parts and the ordinates are measured in the midpoints of each division.

Area = ([O1 +O2 + O3 + …..+ On]*L)/n

L = length of baseline

n = number of equal parts, the baseline is divided

d = common distance between the ordinates

Example of the area calculation by midpoint ordinate rule

The following perpendicular offsets were taken at 10m interval from a survey line to an irregular boundary line. The ordinates are measured at midpoint of the division are 10, 13, 17, 16, 19, 21, 20 and 18m. Calculate the are enclosed by the midpoint ordinate rule.

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Field work in Chain survey | Surveying in Civil Engineering

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Field work in Chain surveying | Surveying and Levelling

Earlier, we discussed “Principles of Chain Surveying” and the considerations that are taken for carrying out Chain Surveying… In this article, we will discuss various instruments that are essential for carrying out Chain Surveying.

Here are the steps to be followed for carrying out Chain Surveying:

  1. Reconnaissance Survey
  2. Marking stations
  3. Running survey lines
  4. Taking offsets

Instruments used in Chain Survey

  1. Chain, 20m or 30m long
  2. Tape
  3. Arrows
  4. Ranging rods
  5. Wooden or Iron Pegs
  6. Plumb bob
  7. Cross staff

Chain used for Surveying

20m chain – 100 links

30m chain – 150 links

1 links – 20cm

Links of chain are made by mild steel wire – 4mm diameter.

Chain used for Chain Surveying
Chain used for Chain Surveying

Each link at the end is bent into a loop and is connected to adjoiningly by means of three oval rings which offers flexibility to the chain. Ends of chains carry brass handle.

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Introduction to Surveying | Civil Engineering

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Surveying

Surveying is the art of making suitable measurements in horizontal or vertical planes. This is one of the important subjects of civil engineering. Without taking a survey of the plot where the construction is to be carried out, the work cannot begin.

Surveying Chart
Surveying Chart

Levelling

Levelling is the art of representing relative positions in the vertical plane of different points on the earth’s surface.

It helps in determining the areas that are to be levelled to achieve a certain slope.

Principles of Surveying

All the surveys that are conducted are based on two fundamental principles. They are as follows:

  1. Working from whole to part
  2. Fixing a point with reference to two fixed points

Working from whole to part

In order to localize errors and prevent their accumulation, a set of control points is always established with great precision first for the whole area to be surveyed.

Later on, details or filled in between these control points to a relatively smaller precision.

This fundamental work principle is known as “Working from whole to part”.

Fixing a point with reference to two fixed points

Survey stations are fixed by atleast two measurements, either both linear or angular measurements or linear and angular measurements from two control points.

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