This blog is purely dedicated to discuss the theories, procedures and methods of Surveying. In case you are someone who is from Civil Engineering field, this blog will improve or keep you in touch with this art. So, after reading the articles, subscribe yourself through the email to keep track of the posts.
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Minor Surveying Instruments
There are some instruments used for the rough surveys, they are not used for the precise surveys:
It is compact instrument used for locating contours, taking cross sections in reconnaissance surveys.
It is a light compact instrument used for measuring vertical angles, finding out slope of the ground and for locating points on a given grade. There are three commonly used forms of clinometers:
(i) Abney's level
(ii) Tangent Clinometer
(iii) Ceylon Ghat Tracer
It is a reflecting instrument capable of measuring up to 120 degrees with an accuracy of one minute. It is one of the most precise hand instrument.
Pantagraph: It is used to reduce or enlarge the given figure.
Planimeter: It is used to measure the area of the given figure.
Reference: surveying Vol-1,2, by Dr. B.C.Punmia, Kanetkar, and internet surfing
Tacheometry is the branch of Surveying in which we determine the horizontal and vertical distances with the angular measurements with an instrument , Tachemometer. It is not so accurate method of finding the horizontal distances as the Chaining is, but it is most suitable for carrying out the surveys to find the distances in the hilly area where other methods are quite difficult being carried out. It is generally used to locate contours, hydrographic surveys and laying out routes of highways, railways etc.
The instruments required for carrying out the Tacheometric survey are: (1) A Tacheometer (2) A Stadia Rod. Tacheometer: Tacheometer is more or less a Theodolite installed with a stadia diaphragm. Stadia diaphragm is equiped with three horizontal hairs and one vertical hair. So we can take three vertical staff reading at the same instruments setting, lower most hair reading, central hair reading and the top hair reading. The difference between the lower hair reading and the upper ha…
A short introduction to plane tabling- A graphical method of Surveying.
Plane Table Survey: Plane Table Survey is a method of Surveying in which field work and the office work are done simultaneously. It is also known as the graphical method of Surveying. A manuscript map is made in the field and the topographic details can be filled in later.
List of Instruments used in Surveying:
(1) Plane Table(2) Alidade(3) Plumbing fork and Plumb bob(4) Spirit Level(5) Chain or Tape(6) Rain roof cover for the plane table(7) Compass(8) Ranging Rods(9) Drawing Sheets(10) Drawing equipment.
Procedure: To do the plane tabling one has to follow the following procedure at every plane table set-up: (a) Fixing the plane table to the tripod stand(b)Setting up and temporary adjustments:
Leveling the plane table with the help of spirit level Centering with the help of plumbing fork Orientation by trough compass or by back sighting
Trigonometric Leveling is the branch of Surveying in which we find out the vertical distance between two points by taking the vertical angular observations and the known distances. The known distances are either assumed to be horizontal or the geodetic lengths at the mean sea level(MSL). The distances are measured directly(as in the plane surveying) or they are computed as in the geodetic surveying.
The trigonometric Leveling can be done in two ways: (1) Observations taken for the height and distances (2) Geodetic Observations. In the first way, we can measure the horizontal distance between the given points if it is accessible. We take the observation of the vertical angles and then compute the distances using them. If the distances are large enough then we have to provide the correction for the curvature and refraction and that we provide to the linearly to the distances that we have computed. In the second way, i.e geodetic observations, the distances between the two points are g…