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Compass Surveying: Measuring Directions and Angles with a Prismatic Compass, Lecture notes of Survey Sampling Techniques

This document, authored by Prof. RD Gupta from MNNIT Allahabad (India), provides an in-depth exploration of compass surveying. Topics covered include the designation of bearings, magnetic declination, compass surveying techniques, and the calculation of bearings from included angles. The document also discusses instruments used in compass surveying, such as the prismatic compass and its parts.

Typology: Lecture notes

2020/2021

Uploaded on 01/30/2022

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B. Tech. IV Semester (Civil Engineering)
CE: 14102 SURVEYING
Unit-II: Measurement of Direction and Angle, Traversing
(Part-I: Measurement of Direction)
By Prof. RD Gupta, MNNIT Allahabad (India)
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Download Compass Surveying: Measuring Directions and Angles with a Prismatic Compass and more Lecture notes Survey Sampling Techniques in PDF only on Docsity!

B. Tech. IV Semester (Civil Engineering)

CE: 14102 – SURVEYING

Unit-II: Measurement of Direction and Angle, Traversing

(Part-I: Measurement of Direction)

Unit-II: Measurement of Direction and Angle, Traversing

Syllabus

➢ Designation of Bearings and inter-conversion, ➢ Included angles from bearings and vice versa, ➢ Magnetic declination, local attraction, ➢ Temporary adjustments and parts of prismatic compass; ➢ Vernier Theodolite, measurement of horizontal angles: repetition method & reiteration method, traversing by compass and theodolite, computations of traverse coordinates, traverse adjustment; Total Station

Compass Surveying

Compass Surveying is the branch of Surveying in which directions of all the survey lines are determined with a compass and the length of the survey lines are measured with a tape. ✓ In practice, Compass Survey is generally used to run a traverse. ✓ In a traverse, framework consists of a series of connected survey lines to form an open or closed polygon. ➢ When the lines form a framework which ends at the starting point, it is known as a closed traverse. ➢ If the framework ends elsewhere, it is said to be an open traverse.

Compass Surveying

Location of a Point by Distance and Direction The direction of a line is defined by a horizontal angle with respect to a reference line. ✓ This reference line is known as Meridian.The horizontal angle measured with respect to reference line (i.e. meridian) is termed as Bearing. In relative direction, the reference line does not remain fixed over a period of time.

Meridians and Bearings

1. Magnetic Meridians : Magnetic Bearing

2. True Meridian : True Bearing

3. Arbitrary Meridian : Arbitrary Bearing

Meridians

The reference line with respect

to which horizontal angle of a

survey line is measured is called

as meridian.

1. True Meridian

✓ True Meridian through a point is the great circle passing through the point, geographical North and South poles. ✓ Thus, true meridian may be considered as a plane passing through the point on the surface of Earth and containing the axis of rotation of the earth. ✓ The direction of true meridian through a point is established by astronomical observations. ✓ The true meridian does not change with time.

Bearings

Bearing of a line is its direction measured with reference to a given meridian.

Three types of Bearings:

1. True Bearing

2. Magnetic Bearing

3. Arbitrary Bearing

✓ True Bearing or Azimuth of a line is its horizontal angle from the true meridian, i.e. Geographical North. ✓ Arbitrary Bearing of a line is the horizontal angle which it makes with any arbitrary meridian ✓ The horizontal angle which a line makes with the magnetic meridian is called Magnetic Bearing.

Designation of Bearings

Inter-conversion

Designation of Bearings

RB / QB : Reduced Bearing or Quadrantal Bearing System

WCB & RB Systems Represented Together

Inter-conversion: RB to WCB

Fore Bearing & Back Bearing

FB & BB

Thanks to all of You Any Questions!