CHAIN SURVEYING

• PRINCIPLE OF CHAIN SURVEYING     

The principle of chain surveying is triangulation. This means that the area to be surveyed is divided into a number of small triangles which should be well conditioned. In chain surveying, the no angular measurements are taken. Here, the tie lines and check lines control the accuracy of work.

      It should be noted that plotting triangles requires no angular measurements to be made, if the three sides are known  

          Chain surveying is recommended when

               1.The ground surface is more or less level

               2.A small area is to br surveyed,   

               3.A small-scale map is to be prepared, and

               4.The formation of we'll-conditioned triangles is easy. 

          Chain surveying is unsuitable when

               1.The are is crowded with many details, 

               2.The area consists of too many undulations, 

               3.The area is very large, and

               4.The formation of well-conditioned triangles becomes difficult due to obstacles. 

Large-Scale and Small-Scale Maps

When 1 cm of a map represent a small distance, it is said to be a large-scale map. 

      For example, 

                                    1 cm =1 m, I. e.   RF = 1/100

When 1 cm of the map represents a large distance, it is called a small-scale map. 

          For example, 

                                      1 cm = 100 m,  I. e.   1 RF = 1/10000

    A map having an RF of less than 1/500 is considered to be large-scale. A map of RF more than 1/500 is said to be small-scale.