Surv 2

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iCAST2

Subdecks (1)

Cards (45)

  • METHODS FOR LINEAR
    MEASUREMENT
    • Pacing
    • Taping
    • Tachymetry
    • Graphic and Math
    • Mechanical Devices
    • Photogrammetry
  • PACING
    • Simplest method of measuring distances.
    • It is used in instances where approximate results can be
    enough for the data needed, such as getting the rodman in
    position during cross-section survey, or simply measuring a
    relatively short distance where accuracy is not that of an issue.
    • Consists of counting the number of steps in a required distance.
  • PACE
    • The length of a single step.
    • Measured heel-to-heel or toe-
    to-toe.
  • STRIDE
    • Two paces or a double step
  • PACE FACTOR
    • Determined by dividing the
    measured or known length of
    a line by the mean number of
    paces taken to walk the line.
  • PACED DISTANCE
    • Length of a course as
    determined by pacing.
  • TACHYMETRY / TACHEOMETRY
    • Takus – “swift” ; metron – “measurements”
    • Surveying method used to quickly determine the horizontal
    distance to, and elevation of, a point.
    • Based on the optical geometry of the instruments employed
    (indirect method of measurement)
    • Two generally accepted practices under tachymetry are
    measurements made with subtense bar and stadia.
  • STADIA METHOD
    • Introduced by James Watt (1771)
  • STADIA METHOD
    • Introduced by James Watt (1771)
    • Has a relative precision of 1/300 to 1/1000
    • Consists of a telescope with two horizontal hairs (stadia hairs)
    and a graduated rod (stadia rod)
    • Surveyor sights through the telescope and takes readings
    where the stadia hairs intersect the graduated rod.
    • The difference between the two readings is called the rod intercept
  • TAPING
    • Usage of a graduated tape and is the most common method of
    measuring horizontal distances
  • CHAINING
    • Measurement of distances using chains
  • CHAINMEN
    • Persons undertaking measurement using chains
  • STEPS IN TAPING
    1. Lining in
    2. Applying Tension
    3. Plumbing
    4. Making Tape Length
    5. Recording Tape
    6. Recording Distance
  • TAPE CORRECTIONS
    1. Incorrect Tape Length or Standardization Error
    2. Temperature Variations
    3. Slope
    4. Sag
    5. Incorrect Tension
  • FACTORS AFFECTING PRECISION
    1. Refinement with which the instrument was manufactured
    2. Roughness of the ground
    3. Skill of the observer
    4. Effects of refraction and parallax