Definition, principles, classification, fields and office work, scales, conventional signs, survey instruments, their care and adjustment, ranging and chaining, reciprocal ranging, setting perpendiculars, well-conditioned triangles, traversing, plotting , enlarging and reducing figures

1. Chain surveying

2. Chain Surveying
• Chain (Tape) surveying is the simplest form of detail surveying.
• In this method the lengths of lines marked on the field are measured,
while the details are measured by offsets from these line.
• Chain surveying is the type of surveying in which only linear
measurements are taken in the field.
• This type of surveying is done for surveying of small extent to
describe the boundaries of plots of land and to locate the existing
feature on them.
• It is the method of surveying in which the area is divided into
network of triangles and the sides of the various triangles are
measured directly in the field with a chain or a tape and no angular
measurements are taken.

3. Principles of Chain Surveying
• The principle of chain surveying is to divide the area into a number
of triangles .
• As a triangle is the only simple plane geometrical figure which can
be plotted from the length of the three sides even if the angles are
not known.
• A network of triangles is preferred to chain surveying.
• Triangulation is the principle of chain surveying.
• If the area to be surveyed is triangle in shape and if the lengths and
sequence of its three sides are recorded, the plan of the area can be
easily drawn.

4. Principles of Chain Surveying

5. Principles of Chain Surveying

6. FIELD WORK & OFFICE WORK
Reconnaissance-
The preliminary inspection of the area to be surveyed is called reconnaissance.
Marking stations-
Stations are marked with ranging rod, or wooden peg, driving a nail or spikes if hard surface, or embedding stone
with a cross mark
Reference sketches-
After marking the station should be referenced i.e. located by measurement called ties taken from 3 permanent
points which are easily identified such as corner of building.
Running survey line-
After the preliminary work, chaining is started from base line and carried throughout all the line of the framework
continuously. So chain is laid and kept lying, offset are taken to locate the nearby details. Make ranging wherever
necessary.

7. Suitability of chain surveying:
Ground surface is more or less level.
Area is small.
Small-scale map is required to prepare.
Formation of well conditioned triangle is easy.
Chain surveying is not recommended when:
Area is crowded with many details.
Area consists of too many undulations.
Area is very large.
Formation of well conditioned triangle is not easy.

8. Well conditioned triangle, ill conditioned
triangle and ideal triangle.
• A triangle is said to be well conditioned triangle when no
angle in it is neither less than 30 nor greater than 120.
• If in a triangle an angle is less than 30 or greater than
120 is called ill conditioned triangle.
• An equilateral triangle having each angle of 60 is an ideal
triangle.

9. Well conditioned triangle, ill conditioned
triangle and ideal triangle.

10. Ranging and Chaining

11. Ranging [Direct and Indirect]

12. Reciprocal Ranging

13. Setting Perpendiculars

14. Traversing

15. Plotting

16. SCALE
• Scale is a fixed ratio that every distance on the plan bears with corresponding distance on the ground.
• One centimetre on the plan represents some whole number of the metres on the ground.
1cm = 10m [This type of scale is called engineering scale].
• 1 unit of length on the plan represents some number of same units of length on the ground.
i.e. 1/1000 etc.
• This ratio of map distance to the corresponding ground distance independent of units of measurement is
called Representative Factor (RF).
• For example,
1cm = 50m
RF = 1/(50×100) = 1/5000
• Above two types of scales are also known as numerical scales.