Chain surveying (plane surveying) constructs a map by combining linear measurement along a control baseline with perpendicular offset measurements to peripheral detail, following the surveying principles of working from whole to part, redundancy, and provision for a check. Offsets are classified as perpendicular or oblique and recorded against chainage in a field book, with offset density governed by the required plotting scale and accuracy; perpendiculars themselves are established or dropped using cross-staff and optical-square instruments, or by tape-based geometric constructions (equal-arc bisection, the Pythagorean 3-4-5 relation), and parallel lines are constructed from congruent perpendicular offsets or equal-segment geometric constructions. Map accuracy is quantified as relative error by comparing an independently measured ground distance to the corresponding scaled distance on the plotted map. This lecture belongs to the domain of plane surveying, specifically the linear-measurement (chain-and-tape) module of introductory surveying methodology.
Chain surveying (plane surveying) constructs a map by combining linear measurement along a control baseline with perpendicular offset measurements to peripheral detail, following the surveying princi…