Hello, guys here we will see types of chain in surveying. When you move toward the survey of land then you have to take several measurements or distance between two points.
So, this measurement is measured by some standard measuring devices that may be electronic like the total station, theodolite, EDM, etc. or mechanical devices like chain and tape.
The chain is used to measure the distance of the land. There are different types of chains for the survey. The chain has its own process of folding and opening to measure land. At last, I have provided a chain surveying pdf for download.
Principle of Chain Surveying
The required area is measured along its perimeter. Then the perimeters of the land are joint with other points of the perimeter of the land forming numbers of the triangle.
Now the area of all triangles can find out to get all the area of land. This is known as triangulation.
Types of Chain in surveying
- Metric chain
- Gunter’s chain
- Engineering chain
- Revenue chain
It may be of different lengths. It may be 20 meters and 30 meters. The length of one link is 20 cm. Then you can calculate the numbers of links in a chain.
Then, You have to convert the length of the chain into centimeter by multiplying with 100, and then you have divided it by length of the link.
For example if you have a chain length 30 meter then number of link will be,
Number of link = (30 x 100)/20 = 150 links
It was developed by a civil engineer Gunter So, this chain was named Günter’s chain. It is 66 feet long and has 100 links in one chain tape. Then the length of one links becomes 66/100 feet.
The engineering chain is mostly used in the civil engineering field in survey. Its length is 100 feet and has 100 links. Then the length of one links becomes 1 foot.
The length of the revenue chain is 33 feet and has 16 links. Then the length of one link becomes 33/16 links.
Equipment used for chain surveying
This is a metallic peg or nail-like structure that is used to indicate the measured distance taken by a chain. It is buried at all distances taken by a chain.
Its length is about 40 centimeter and diameter is 4 millimeter.
If the measuring distance is too long then it makes it difficult to measure from one point to another in straightway. So, ranging rod can be placed at the center of chaining to take straight measurement from one point to another.
Its length is 2 meter to 3 meter and diameter is 3 centimetre.
This rod is used to take offset of the measuring line. Offset is the line exactly parallel to the reference line at some distance. It is used to take offset when some obstacle appears at the line of measurement while chaining.
Peg is marking equipment for measurement. It is buried on the ground at some distance to indicate the measuring lines and measurement reading. It is made up of wood. It is generally square in shape. Its length varies from 15 centimeters to 60 centimeters and cross-section varies from 3 cm2 to 5 cm2.
We have discussed types of chain in surveying and Equipment used for chain surveying. Now let us read somewhat about types of tape for the survey.
Types of tape
- Cloth tape
- Metallic tape
- Steel tape
- Invar tape
It is rarely used for the survey because it doesn’t provide accurate measurement due to stretching and twisting of tape.
It also gives fault measurement due to sagging and hogging by absorbing moisture from the environment.
This tape is superior to cloth tape. It is made up of brass, bronze, and other materials. It provides more accurate measurement because it does not absorb moisture from atmosphere and less twisting effect.
This tape is superior to cloth tape and metallic tape. This tape is made up of steel and having less stretching effect due to warm weather.
This tape is superior to all tapes. This tape is made up of an alloy of nickel. This tape is used for measuring the accurate measurement for the baseline survey of the land.
It has a negligible effect on temperature, humidity, sagging, etc.
Opening or Unfolding of Chain
The chain has two handles to measurement. Both handles are attached at both ends of the chain. To unfold chain, first of all, catch both handles with one hand (left hand) and all the chain with the other hand (Right hand).
After that throw chain as far as possible so that it can unfold taking two lines of the chain. Because you have taken both ends of the chain.
Folding of chain
To fold the chain finds the center point of the chain. You can find a metallic tag at the center of the chain. Now, fold all the chain individually in both directions of the chain. Don’t mix the chain with each other from the center of the chain.
At last, make a bundle of chains and bind with any materials. You can unfold the chain in the same process as told in the above opening of the chain.
Download chain surveying pdf
I hope this article remains helpful for you.
Happy Learning – Civil Concept
Civil Engineer – Ranjeet Sahani