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Distance Between Two
Points
Pacing
Chaining
Temperature
Standardisation
Catenary
Slope
Tension
Tachaeometry
Stadia System
Measurement of
Tacheometric Constants
Refraction and Curvature
Theodolite
Tachaeometry
Field Tachaeometry
Electronic Tachaeometry
Chaining
Historically a chain made up of 100 links was used for distance measurement, and this terminology has stayed with surveying ever since. Chainage is a bit of jargon that now applies to measurement with a steel band, fibreglass tape, 'Stylon' tape, or a cloth tape; in fact any item that measures the distance directly in the field. It is fairly quick, easy and cheap, and hence is the most common form of distance measurement. Unfortunately, chainage is prone to errors and mistakes and these will be discussed later, but this is the fundamental technique used for distance measurement in planar geomatics science.
Corrections for Chainages
Listed below are several corrections that can be applied to chained distances to minimize systematic errors and to correct for the effects of the physical environment of the measurement process.
The expressions below are used on the following pages:
| L - | true length |
| l - | length as measured |
| to - | temperature of standardization |
| t - | temperature at observation |
| Dt - |
(t - to) |
| M - | mass per unit length |
| to - | standard tension |
| DT | (T - To) |
| T - | Field tension |
| c - | coefficent of linear expansion |
| E - | Young modulus |
| q - | angle of slope in degrees |
| l' - | actual standardized length |
| DL - | correction to length |