JNTU B.Tech II SURVEYING Previous Question Paper (August/September - 2022 - R16)

Surveying chains are classified based on their length and construction material. The primary types are:

• Metric Chain: Available in 20m and 30m lengths, divided into 20cm links. These are the standard in modern surveying due to their decimal system, which simplifies calculations.
• Gunter's Chain (Surveyor's Chain): 66 feet long with 100 links. It is specifically designed for land area measurements where 10 square chains equal 1 acre, making it highly advantageous for cadastral surveys.
• Engineer's Chain: 100 feet long with 100 links. Each link is 1 foot long. It is preferred for large-scale engineering works where measurements are required in feet and inches.
• Revenue Chain: 33 feet long with 16 links. It is primarily used for cadastral surveys in India for measuring small fields.
• Steel Band (Band Chain): Consists of a long ribbon of steel with graduations. It is the most accurate type, though it is more fragile and prone to kinking compared to link chains.

When two stations A and B are not intervisible due to a hill, the process of indirect ranging (or reciprocal ranging) is employed. This requires two surveyors to stand at intermediate points M1 and N1 such that they can see both A and B.

The procedure is as follows:

1. Two surveyors stand at M1 and N1, positioned such that M1 can see N1 and B, and N1 can see M1 and A.
2. The surveyor at M1 directs the person at N1 to a new position N2 so that N2 is in line with M1 and B.
3. The surveyor at N2 then directs the person at M1 to a new position M2 so that M2 is in line with N2 and A.
4. This process of shifting the intermediate points is repeated until M and N are in a straight line with A and B.

The sketch involves a plan view showing the line AB obstructed by a central rise, with the points M1, N1 shifting iteratively to M, N until the line of sight is clear and collinear.