Tuesday, October 18, 2022

Basics on Tacheometric Surveying - PDF

Tacheometry or tachemetry or telemetry is a branch of angular surveying in which the horizontal and vertical distances of points are obtained by optical means as opposed to the ordinary slower process of measurements by tape or chain.

The method is very rapid and convenient.
  • It is best adapted in obstacles such as steep and broken ground, deep ravines, stretches of water or swamp and so on , which make chaining difficult or impossible,
  • The primary object of tacheometry is the preparation of contoured maps or plans requiring both the horizontal as well as vertical control. Also, on surveys of hogher accuracy, it provides a check on distances measured with the tape.
  • Tacheometry (from Greek, quick measure), is a system of rapid surveying , by which the positions, both horizontal and vertical, of points on the earth surface relatively to one another are determined without using a chain or tape or a separate leveling instrument.

Uses of Tacheometry
  • The tacheometric methods of surveying are used with advantages over the direct methods of measurement of horizontal distances and differences in elevations.Some of the uses are :
  • Preparation of topographic maps which require both elevations and horizontal distances.
  • Survey work in difficult terrain where direct methods are inconvenient.
  • Detail filling
  • Reconnaissance surveys for highways, railways, etc.
  • Checking of already measured distance.
  • Hydro-graphic surveys and
  • Establishing secondary control.

  • An ordinary transit theodolite fitted with stadia diaphragm is generally used for tacheometric survey.
  • The stadia diaphragm essentially consists of one stadia hair above and the other an equal distance below the horizontal cross hair the stadia hairs being mounted in the ring and on the same vertical plane as the horizontal and vertical cross hairs.

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