BEARINGS AND AZIMUTHS

BEARINGS AND AZIMUTHS

  • Horizontal angles are angles measured in a horizontal plane by a level instrument
  • Used to determine:
  • The units of measurement most commonly used in surveying is the sexagesimal system

    TYPES OF ANGLES

  • Interior angles
  • Deflection angles

    DIRECTIONS OF LINES

  • Defined by a horizontal angle between the line and a defined reference line called a meridian
  • True meridian is the north-south reference line through the earthÆs geographic poles
  • Magnetic meridian is a north-south reference line as defined by the earthÆs magnetic field
  • An assumed meridian can arbitrarily chosen to serve as a reference for all other lines in a survey

    BEARINGS

  • Designate the direction of a line by an angle and quadrant letters. (e.g. N30° E)
  • Bearings are never greater than 90°
  • Bearings are referenced from north or south and the angle to the east or west from the north-south meridian.
  • True bearings are based on true north.
  • Magnetic bearings are based on magnetic north.

    TRUE BEARINGS



    BEARING DIRECTION



    MAGNETIC BEARINGS



    AZIMUTHS

  • Angles measured clockwise from any reference meridian
  • Azimuths range from 0 to 360°
  • Azimuths are referenced from north
  • True azimuths are based on true north
  • Magnetic azimuths are based on magnetic north