Direct Ranging

This method is possible if the first and last points are intervisible. Given figure shows the intervisible stations A and B in which an intermediate point C is to be located. Point C is chosen at a distance slightly less than a chain length. Ranging rods are fixed at points A and B. Assistant holds another ranging rod near C. Surveyor positions himself about 2 m behind station A and looking along line AB directs the assistant to move at right angles to the line AB until he aligns the ranging rod along AB. Then surveyor directs the assistant to mark that point and stretch the chain along AC.

                        (a) Plan view

                       (b) Sectional view

.                           Direct ranging