Measuring of Horizontal angle Practical Part
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This document is a practical report on the use of a theodolite in surveying, detailing the setup and methods for measuring horizontal and vertical angles. It outlines three methods for measuring horizontal angles: ordinary, repetition, and reiteration, and explains how vertical angles are measured in relation to the horizontal plane. The report includes instructions for ensuring accurate measurements and minimizing instrumental errors.
Measuring of Horizontal angle Practical Part
- 1. 1 Erbil Polytechnic University Technical Engineering College Civil Engineering Department Surveying Engineering Plane and Applied surveying 2 Theodolite practical part 1
- 2. Report number(1) Report name: Setting up Theodolite Instrument Measuring Horizontal and Vertical Angle. Apparatus: Theodolite Instrument 1 No. Tripod 1 No. Pin 3 Nos. Tape 1 No. Range pole 2 Nos. Object : 1. To perform temporary adjustment of theodolite instrument 2. Measuring of Horizontal angle H.A Face Left (F.L) and face right(F.R) . 3. Measuring of Vertical angle V.A Face Left (F.L) and face right(F.R) 2
- 4. Measuring Horizontal Angle There are three methods of measuring horizontal angles: i) Ordinary Method ii) Repetition Method. iii) Reiteration Method. 4
- 5. 5 Angular measurement : Angular measurement is made using surveying instruments which measure both horizontally and vertically in degrees. Degrees are sexagesimal units which are subdivided into minutes and seconds in exactly the same manner as time. q = 25°48'30"
- 6. Calculation and Measuring Horizontal Angle i)Ordinary Method. To measure horizontal angle: 1-Set up the theodolite at station point ( O) Direct telescope to point A and set the horizontal angle to the zero or 360°. 2-Turn the instrument clockwise and direct the telescope towards B and read the horizontal B and record both the readings. 3-The reading angles at B gives the value of the angle AOB directly. 6 A B O
- 7. Measuring Horizontal Angle 4-Change the face of the instrument and repeat the whole process. The mean of the two readings gives the second value of the angle AOB which should be approximately or exactly equal to the previous value. 5-The mean of the two values of the angle AOB ,one with face left and the other with face right ,gives the ,required angle free from all instrumental errors. 7 A B O HORIZONTAL ANGLE AOB
- 8. Measuring Horizontal Angle ii) Repetition Method. This method is used for very accurate work. The No. of repetitions made usually in this method is six, three with the face left and three with the face right .In this way ,angles can be measured to a finer degree of accuracy . 8
- 10. Measuring Horizontal Angle iii) Reiteration Method It is generally preferred when several angles are to be measured at a particular station. This method consists in measuring several angles successively and finally closing the Horizon at the starting point. The final reading of the point A should be same as its initial reading. 10
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- 12. Measurement of horizontal angles: 12
- 13. Measuring Vertical Angle Vertical Angle : A vertical angle is an angle between the inclined line of sight and the horizontal. It may be an angle of elevation or depression according as the object is above or below the horizontal plane. 13
- 14. Measuring Vertical Angle 14 Measuring Vertical angles Face Left V-angle= 90- Zenith angle Face Right V-angle= Zenith angle-270
- 15. Measurement of Vertical angles: F.L= 90˚- Zenith angle. F.R= Zenith angle - 270˚ 15