Offsets

For locating ground features Lateral measurements to chain lines are known as offsets. Perpendicular or oblique offsets may be taken for this purpose .If the object to be located (say road) is curved more number of offsets should be taken. For measuring offsets tapes are used commonly.

                                              (a)

                                    (b)

                                           Offsets

Any one of the following methods is used for setting perpendicular offsets:

1.   Swinging
2.   By Using cross staffs
3.   By Using optical or prism square.