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# Fore Bearing And Back Bearing In Surveying Pdf

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Published: 11.04.2021

## Azimuths and Bearings in Surveying-Difference & Determination

This direction is known as magnetic meridian. The angle between the magnetic meridian and a line is known as a magnetic bearing or simple bearing of the line. Grid meridian: Sometimes for preparing a map some state agencies assume several lines parallel to the true meridian for a particular zone these lines are termed as grid meridian.

Quadrantal Bearing: The magnetic bearing of a line measured clockwise or anticlockwise from NP or SP whichever is nearer to the line towards the east or west is known as QB. Reduced Bearing: When the whole circle bearing of a line is converted to quadrantal bearing it is termed as a reduced bearing.

Magnetic declination: The horizontal angle between the magnetic meridian and true meridian is known as magnetic declination. Dip of the magnetic needle: If the needle is perfectly balanced before magnetisation, it does not remain in the balanced position after it is magnetised.

This is due to the magnetic influence of the earth. The needle is found to be inclined towards the pole. This inclination of the needle with the horizontal is known as dip of the magnetic needle. First Method : Sum of the interior angle should be equal to 2n-4 x Then starting from unaffected line the bearings of all the lines are corrected using corrected interior angles. Second Method: Unaffected line is first detected.

Then, commencing from the unaffected line, the bearing of other affected lines are corrected by finding the amount of correction at each station. Have an account? Sign In Now. Remember Me! Don't have account, Sign Up Here.

## SURVEY FORE BEARINGS(FB) & BACK BEARINGS(BB)

Bearings of lines may be calculated if bearing of one of the lines and the included angles measured clockwise between the various lines are given. In a closed traverse, where local attraction is not suspected i. The ordinary compass cannot read directly the angle between two lines. The angles can be determined by observing the bearings of the two lines from their point of convergence. When the two lines meet at a point, two angles interior and exterior and formed. The following rules may be employed to find the angles between the lines whose bearings are given.

Bearings measured in the direction of progress of the survey are known as fore bearing and bearings measured opposite to the direction of the survey are known as back bearing. The bearing of a line is the direction with respect to a given meridian; Meridian is a fixed reference line. While setting out a survey line, the bearing readings are necessary. Fore Bearing - Bearing measured in the direction of progress of the survey. Back Bearing - Bearing measured opposite to the direction of survey.

The bearings obtained in surveyor's compass are the quadrantal bearings. Fore and back Bearing. The bearings of a survey line in the direction of the survey is.

## Calculation of Angles from Bearings | Compass Surveying | Surveying

Local attraction is the phenomenon by which the magnetic needle is constantly prevented to point towards the magnetic north at a place. This is because that these magnetic compass is influenced by other magnetic objects at that locality such as wires carrying electric current, rails, steel and iron structures, steel tapes etc. The occurrence of local attraction can be detected by observing the difference between the fore and back bearings. If there is no influence of local attraction and other error, this difference will be

Taking a forward bearing. The first compass bearing we need to take is from our known location to our cabin on the far shore. The bearing we end up with represents the angle between a line from Magnetic North to our location, and a line from our location to the cabin. These bearings in the opposite direction are called back bearings or reciprocal bearings.

In navigation , bearing is the horizontal angle between the direction of an object and another object, or between it and that of true north. In nautical navigation the absolute bearing is the clockwise angle between north and an object observed from the vessel. If the north used as reference is the true geographical north then the bearing is a true bearing whereas if the reference used is magnetic north then the bearing is a magnetic bearing. An absolute bearing is measured with a bearing compass.

The bearing we end up with represents the angle between a line from magnetic north to our location, and a line from our. Surveying is a very important part of civil engineering.

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ИСТЕКШЕЕ ВРЕМЯ: 15:17:21 - Пятнадцать часов семнадцать минут? - Он не верил своим глазам.  - Это невозможно. Он перезагрузил монитор, надеясь, что все дело в каком-то мелком сбое.

Плутоний и уран, - повторял Джабба.  - Переходите к главному.

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ГЛАВА 42 Вернувшись в комнату, Сьюзан, не находя себе места, нервно ходила из угла в угол, терзаясь мыслью о том, что так и не выбрала момент, чтобы разоблачить Хейла. А тот спокойно сидел за своим терминалом. - Стресс - это убийца, Сью. Что тебя тревожит. Сьюзан заставила себя сесть.

Нам обоим грозит опасность. Сьюзан не верила ни единому его слову. Хейл подтянул ноги и немного приподнялся на корточках, желая переменить позу.

1. ## Sharon G.

17.04.2021 at 00:14