What Is Azimuths Surveying | What Is Bearings Surveying | Difference Between Azimuths and Bearings in Surveying

Difference Between Azimuths and Bearings in Surveying (1)

What Is Azimuths Surveying?

Azimuths are defined as horizontal angles that are measured from the reference meridian in the clockwise direction. Azimuths are also called whole circle bearing systems (W.C.B). Azimuths are used in compass surveying, plane surveying, where it is generally measured from the north.

What Is Bearings Surveying?

In land surveying, a bearing is a clockwise or counterclockwise angle between north or south and a direction. In surveyingbearings can be referenced to true north, magnetic north, grid north (the Y-axis of a map projection), or a previous map, which is often a historical magnetic north.

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Difference Between Azimuths and Bearings in Surveying

1. Azimuths Surveying Vs Bearings Surveying: Definitions

Azimuths Surveying: Azimuths are horizontal angles computed in a clockwise manner from the reference meridian. Azimuths are often referred to as a whole circle bearing system (W.C.B). Azimuths are used in compass surveying and aircraft surveying and are typically measured from its north. Azimuths are obtained from the south in astronomical and the army.

Bearings Surveying: The bearing is the acute angle measured between the reference meridian and the given line. The line is measured from north or south to east or west, yielding an angle less than 360 degrees. The angle is denoted by the letters N or S, followed by the angle value and the E or W direction.

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2. Azimuths Surveying Vs Bearings Surveying: Types of Azimuth in Surveying

Azimuths Surveying: The azimuths may be geodetic, astronomic, inferred, recorded, or magnetic in nature, depending on the meridian adopted. It is often recommended to state the comparison meridian before beginning surveying actions to avoid future misunderstandings.

  1. Policy Azimuths: For work-related purposes, azimuths must be interpreted to as north.
  2. Astronomic Azimuths: A azimuth calculated from the astronomical pole in a manner perpendicular to the direction of gravitational at the observation point. Celestial measurements are used to calculate astronomic azimuths.
  3. Geodetic Azimuths: A reference to the pole of a spheroid in a plane perpendicular to the spheroid at the start or end of a line. The Laplace correction can be used to calculate geodetic azimuths from astronomic azimuths. Imagine the minor adjustment required in an instrument to keep it levelled over a point if the plumb line is deflected to visualize the difference between astronomic and geodetic azimuths (deflection of the vertical). This minor adjustment will result in a correspondingly minor change in the measured angle.
  4. Grid Azimuths: The angle in the plan projection between grid north and the straight line from the point of observation to the point observed is known as the grid azimuth. Only when the point of observation is on the central meridian is grid azimuth the same as geodetic azimuth.

Bearings Surveying: Bearing of a line is its direction comparative to a specified meridian.

  1. True Meridian: The true meridian along a line is defined as a line in which a plane aligns the earth’s surface after passing via the true north as well as south extremes As a result, it traverses the true north as well as the south.  Astronomical studies can be used to determine the true meridian’s path via a point.
    • True Bearing: it is a line that is in horizontal angle formed by this with the true meridian through those line’s poles. The true bearing of a line is a consistent amount because the path of the true meridian via a point remains intact.
  2. Magnetic Meridian: A magnetic bearing is measured from a suitable magnetic meridian, a grid bearing from a suitable grid meridian, inferred bearings from a suitable arbitrary meridian, a geodetic bearing from a geodetic meridian, and an astronomic bearing from an astronomic meridian. Observing the needle of the compass yields the magnetic meridian.
    • Magnetic Bearing: The magnetic bearing of a line is the horizontal angle formed by the magnetic meridian passing through one of the line’s extremities. It is measured with a magnetic compass.
  3. Arbitrary meridian: Any convenient direction towards a permanent and important mark or signals, such as a church spire or the top of a chimney, is an arbitrary meridian. These meridians are used to calculate the relative positions of lines in a small area.
    • Arbitrary Bearing: The horizontal angle formed by a line with any arbitrary meridian passing through one of its extremities. It is measured using a theodolite or sextant.

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3. Azimuths Surveying Vs Bearings Surveying: Method of Correcting

Azimuths Surveying: Method of correcting the azimuth in surveying.

A technique for correcting an electronic compass’s azimuth error is revealed.

  1. While spinning the electronic compass 360 degrees, measure a declination value corresponding to a predetermined azimuth angle.
  2. Use a sine function to fit the measured declination value.
  3. Demonstrate a sinusoidal function.
  4. Applying offset, amplitude, and azimuth corrections to the displayed sinusoidal function.

Bearings Surveying: Method of correcting the bearing in surveying.

There are two methods of correcting the bearing affected by local attraction:

  1. Included Angle Method: The traverse’s incorporated angles being determined at first, trailed by the traverse’s right bearings, that are determined to use the included angles again starting from the line that is unaltered by neighborhood fascination.
  2. Error Computation Method: At each survey station, the direction and amount of local attractions are determined. Beginning with a line that is not influenced by local attraction, the corrected bearing of the traverse is calculated. This method is more precise than the included angle method. It is used by the majority of surveyors.

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4. Azimuths Surveying Vs Bearings Surveying: Applications

Azimuths Surveying: Azimuth applications in surveying.

  1. Azimuth is used in boundary, control, and topographic surveys, among other things.
  2. Azimuths are used in compass and aircraft surveying.

Bearings Surveying:

  1. A ‘bearing’ is normally calculated in a clockwise direction starting from a reference direction of 0° and increasing to 359.9 degrees in land navigation.
  2. In aircraft navigation, an angle is commonly measured clockwise from the aircraft’s track or heading.
  3. In naval navigation, starboard bearings are referred to as ‘green,’ while port bearings are referred to as ‘red.

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5. Azimuths Surveying Vs Bearings Surveying: Forward and Back

Azimuths Surveying: Forward and Back Azimuths

  1. The forward azimuth of the line along whereby the poll is being conducted is the forward azimuth, as well as the reversing azimuth is the backward azimuth. Throughout the instance of azimuth, the values for forwarding and backward azimuth would be varied. The backward and forward azimuths can be measured by multiplying or deducting 180°.
  2. If the forward azimuth is much less than 180°, the backward azimuth is calculated by adding 180° to the forward azimuth. If the forward azimuth is larger than 180°, deduct 180° to get the backward azimuth.
  3. Forward azimuth indicates the line’s forward direction, and backward azimuth indicates the line’s backward direction. By adding or subtracting 180 degrees, the forward azimuth may be shifted to the back azimuth.
  4. If line AB has a forward azimuth of 70 degrees, then the backward azimuth would be 70 + 180 = 250 degrees. If the line AD’s azimuth is 230 degrees, the backward azimuth is 230 – 180 = 50 degrees.

Bearings Surveying: Forward and Back Bearings

  1. The forward bearing of a line is the bearing of a line in the direction in which a survey is advancing. Back bearing refers to the bearing of the line in the opposite direction of progress. Forward bearings can be converted to back bearings and vice versa in aircraft surveying.
  2. Both the forward and back bearing values will be the same, but the direction will be opposite. The direction will shift from N or S to S or N, and from E or W to W or E

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Computation of Azimuths and Bearing in Surveying

Sr.No. Quadrant Detail
1 Quadrant 1 North – East Direction: Bearing equals Azimuth
2 Quadrant 2 South-East Direction: Bearing = 180° – Azimuth; Azimuth = 180° – Bearing.
3 Quadrant 3 South – West. Direction : Bearing = Azimuth – 180°, Azimuth =Bearing + 180°
4 Quadrant 4 North – West Direction: Bearing = 360° – Azimuth, Azimuth = 360° – Bearing

Designations of Azimuth and Bearings in Surveying

  1. Back Bearing (BB): Backward Bearing refers to bearings measuring in the opposite way of surveying progress, namely in the backward direction of the survey line.
  2. Fore Bearing (FB): Bearings measured when surveying, i.e. in the forward direction of survey lines, are referred to as fore bearings or forward bearings.
  3. Calculated Bearing: The bearings computed from field observations are referred to as calculated bearings.
  4. Observed Bearing: The bearings taken in the field with an instrument are referred to as Observed Bearings.
  5. Whole Circle Bearing: Bearings measured clockwise from the north are referred to as full circle bearings. The value ranges between 0 and 360 degrees. Bearings measured from the north or south towards the east or west, whichever is closer, are known as diminished bearings. For each quadrant, the values range from 0 to 90 degrees. It is often referred to as quadrantal bearing (QB).

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FAQ

What is Bearing in Surveying?

Bearing is defined as the acute angle that is measured between the reference meridian and the given line. The line is measured either from the north or south towards east or west that would give an angle less than 360 degrees.

What Is Bearing Angle?

In mathematics, a bearing is the angle in degrees measured clockwise from north. Bearings are usually given as a three-figure bearing. For example, 30° clockwise from north is usually written as 030°.

Bearing Vs Azimuth

bearing is an angle less than 90° within a quadrant defined by the cardinal directions. An azimuth is an angle between 0° and 360° measured clockwise from North. “South 45° East” and “135°” are the same direction expressed as a bearing and as an azimuth.

Bearing Degrees

bearing provides a direction given as the primary compass direction (north or south), degree of angle, and an east or west designation. A bearing describes a line as heading north or south and deflected some number of degrees toward the east or west. A bearing, therefore, will always have an angle less than 90°.

Azimuth Meaning

The azimuth is the angle between North, measured clockwise around the observer’s horizon, and a celestial body (sun, moon). It determines the direction of the celestial body. For example, a celestial body due North has an azimuth of 0º, one due East 90º, one due South 180º and one due West 270º.

Bearing to Azimuth

An azimuth circle consists of 360 degrees. Ninety degrees corresponds to east, 180 degrees is south, 270 degrees is west, and 360 degrees and 0 degrees mark north. The word “bearing” is sometimes used interchangeably with azimuth to mean the direction (the degree reading) from one object to another.

Convert Azimuth to Bearings

Converting azimuths to quadrant bearings or vice versa is easy. For example an azimuth of 140° is greater than 90° and less than 180°, therefore it is in SE quadrant. There are 180 – 140 = 40 degrees between the South and the point, therefore the quadrant bearing is S40°E.

Azimuth in Surveying

Azimuths are defined as horizontal angles that are measured from the reference meridian in the clockwise direction. Azimuths are also called a whole circle bearing system(W.C.B). Azimuths are used in compass surveying, plane surveying, where it is generally measured from the north.

Azimuth to Bearing

Converting azimuths to quadrant bearings or vice versa is easy. For example an azimuth of 140° is greater than 90° and less than 180°, therefore it is in SE quadrant. There are 180 – 140 = 40 degrees between the South and the point, therefore the quadrant bearing is S40°E.

Bearing in Surveying

Bearing is defined as the acute angle that is measured between the reference meridian and the given line. The line is measured either from the north or south towards east or west that would give an angle less than 360 degrees.

Azimuth Direction

An azimuth is the direction measured in degrees clockwise from north on an azimuth circle. An azimuth circle consists of 360 degrees. Ninety degrees corresponds to east, 180 degrees is south, 270 degrees is west, and 360 degrees and 0 degrees mark north.

Reverse Azimuth

back azimuth is a projection of the azimuth from the origin to the opposite side of the azimuth circle. There are 360 degrees in the azimuth circle, so the opposite direction would be 180 degrees (half of 360 degrees) from the azimuth.

Bearing of a Line

Bearing of a line is the angle measured from either the north or south end of a reference meridian. The angle is observed from north or south towards the east or west, to give a reading less than 90°. Bearing is represented by the letter N or S preceding the angle.

Azimuth Bearing

An azimuth bearing uses all 360° of a compass to indicate direction. The compass is numbered clockwise with north as 0°, east 90°, south 180°, and west 270°. So a bearing of 42° would be northeast and a bearing of 200° would be southwest, and so on.

How to Calculate Azimuth?

There are specific rules for calculating in either direction. To calculate azimuths clockwise around a traverse: Subtract the interior angle from the back azimuth of the preceding line. To calculate azimuths counter-clockwise around a traverse: Add the interior angle to the back azimuth of the preceding line.

Convert Bearing to Degrees

To convert angle of bearing to degrees of a standard angle, subtract the bearing angle from 90°. If you end up with a negative answer, add 360°, and if your answer is greater than 360°, subtract 360° from it. For a bearing angle of 180°, the standard angle would be 270°

Azimuth and Bearings

bearing is an angle less than 90° within a quadrant defined by the cardinal directions. An azimuth is an angle between 0° and 360° measured clockwise from North. “South 45° East” and “135°” are the same direction expressed as a bearing and as an azimuth.

Calculate Azimuth

To calculate azimuths about a traverse, it is necessary to obtain the back azimuth of a line. To calculate a back azimuth, simply add 180° to the azimuth of the line. For example, if a line has an azimuth of 75, its back azimuth would be 255°. If a line has an azimuth of 150, its back azimuth would be 330.

How to Read Bearings?

The bearing of a point is the number of degrees in the angle measured in a clockwise direction from the north line to the line joining the centre of the compass with the point. A bearing is used to represent the direction of one point relative to another point. For example, the bearing of A from B is 065º.

Difference Between Heading and Bearing

The difference between heading and bearing in navigational terms. Heading is the direction the aircraft is pointing. The aircraft may be drifting a little or a lot due to a crosswind. Bearing is the angle in degrees (clockwise) between North and the direction to the destination or nav aid.

Convert Azimuth to Bearing

Converting azimuths to quadrant bearings or vice versa is easy. For example an azimuth of 140° is greater than 90° and less than 180°, therefore it is in SE quadrant. There are 180 – 140 = 40 degrees between the South and the point, therefore the quadrant bearing is S40°E.

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