Traversing is that type of survey in which a number of connected survey lines form the framework and the directions and lengths of the survey lines are measured with the help of an angle measuring instrument and tape or chain respectively. is a method used in land surveying to determine the positions of points on the Earth's surface. It involves measuring angles and distances between a series of points, which are connected in a sequence to form a polygonal shape. This technique is essential for mapping, property boundary determinations, and various engineering applications.
The principle of traversing is that if the direction and length of any line is known then the coordinates of its head (end point) can be found from the given coordinates of its tail (starting point). i.e.
Latitude (∆N) = l cos θ
Departure (∆E) = l sin θ
If coordinate of A is known then coordinate of B can be calculated.
i.e. E2 = E1 + ∆E and
N2 = N1 + ∆N
a. On the basis of starting and ending points
• Closed traverse: The traverse which returns to its starting point, thereby forming a closed polygon. Also, a traverse which begins and ends at the points whose positions on the plan are known is also referred to as closed traverse.
• Open traverse: The traverse, which does not return to the starting point. It consists of a series of lines expanding in same direction. An open traverse cannot be checked and adjusted accurately.
b. On the basis of used instrument and method
• Chain traverse: Linear as well as angular measurements are done with the help of chain and tape only. The measured angles are called chain angles.
• PT traverse: Plane table traverse is the traverse in which alidade is used for direction of traverse leg and distance measured by tape.
• Theodolite traverse: Theodolite traverse is the traverse in which theodolite is used for angular measurement and steel band is used for linear measurement.
c. On the basis of accuracy and precision:
• Primary traverse: Primary traverse is the traverse in which long range EDM is used for distance and precise theodolite T2/ T3 is used for angle measurement.
• Secondary Traverse: Secondary Traverse is the traverse which are used to establish the third and fourth order points
• Tertiary Traverse: Tertiary traverse is the traverse which is conducted under controlled area of primary and second order traverse