Distance Measurement in Engineering Surveying
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Questions and Answers

Where are distances obtained by pacing sufficiently accurate?

  • Surveying, engineering, geology, agriculture, forestry, and military field sketching (correct)
  • Space exploration
  • Construction and architecture
  • Military operations

    • What is a passometer?

  • A tool used for measuring distances by counting steps (correct)
  • A type of tape used for measuring distances
  • A device used for measuring distances on a vehicle
  • A type of chain used for linear distance measurement

    • What is an odometer used for?

  • Measuring distances in agriculture
  • Measuring distances in surveying
  • Converting the number of revolutions of a wheel to a distance (correct)
  • Measuring distances along irregular or curved lines

    • What is a measuring wheel used for?

    <p>Measuring distances along irregular or curved lines and boundaries</p> Signup and view all the answers

    What is a chaining method?

    <p>A method of measuring distances using a chain or tape</p> Signup and view all the answers

    What is a cloth tape used for?

    <p>Ordinary work</p> Signup and view all the answers

    What is a metallic tape used for?

    <p>All survey works</p> Signup and view all the answers

    What is a steel tape used for?

    <p>Standardizing chains and construction work</p> Signup and view all the answers

    What is the limitation of a cloth tape?

    <p>It is affected by moisture and shrinks</p> Signup and view all the answers

    What is invar tape primarily used for?

    <p>Measuring distances with maximum precision</p> Signup and view all the answers

    What is the purpose of an inclinometer or clinometer?

    <p>To measure angles of slope, elevation, or depression</p> Signup and view all the answers

    What should be done to steel tapes after use in wet weather?

    <p>Clean and dry them with an oily rag</p> Signup and view all the answers

    Why should a piece of colored cloth be tied to an arrow?

    <p>To enable the arrow to be seen clearly on the field</p> Signup and view all the answers

    What should be done to ranging rods?

    <p>Erect them as vertically as possible at the exact station point</p> Signup and view all the answers

    What is the fundamental purpose of studying errors in surveying?

    <p>To understand the sources of errors and apply corrections to minimize their effect</p> Signup and view all the answers

    Why should the operating tension of a steel band be indicated?

    <p>To ensure the tape is not damaged</p> Signup and view all the answers

    How often should linen tapes be tested for length?

    <p>Frequently and always after repairs</p> Signup and view all the answers

    What is the main difference between an error and a mistake in surveying?

    <p>Error is a deviation from the exact value, while mistake is a blunder made by the surveyor</p> Signup and view all the answers

    Which of the following is an instrumental error in taping?

    <p>Kinks in the tape</p> Signup and view all the answers

    What is the ranging process?

    <p>The process of establishing intermediate points on a straight line</p> Signup and view all the answers

    What is the effect of sag in the chain or tape on the measurement?

    <p>Cumulative +</p> Signup and view all the answers

    When is direct ranging done?

    <p>When the two ends of the survey lines are inter visible</p> Signup and view all the answers

    What is the purpose of ranging alignment in chaining?

    <p>To ensure the tape is aligned with the direction of measurement</p> Signup and view all the answers

    Which of the following is a personal error in taping?

    <p>Tapeperson reading the tape incorrectly</p> Signup and view all the answers

    What is the effect of non-horizontal alignment of the tape during measurement?

    <p>Cumulative +</p> Signup and view all the answers

    Which of the following is an example of a mistake in chaining?

    <p>Displacement of arrows and not replacing them in proper position</p> Signup and view all the answers

    What is the main reason for booking of data in surveying?

    <p>To record the measurements for future reference</p> Signup and view all the answers

    What is the actual length of the standard tape in the given example?

    <p>30.003</p> Signup and view all the answers

    What is the temperature at which tapes are usually standardized?

    <p>20ºC</p> Signup and view all the answers

    What is the coefficient of expansion of Invar tapes?

    <p>0.50 × 10−6 per ℃</p> Signup and view all the answers

    What is the formula for temperature correction?

    <p>Ct = ∝ × L × ΔT</p> Signup and view all the answers

    What is the principle of Chain Triangulation?

    <p>Dividing the area into small triangles</p> Signup and view all the answers

    What is the measured length of the line AB in the given example?

    <p>348.28</p> Signup and view all the answers

    What is the error in the tape used to measure the line AB in the given example?

    <p>0.05 m</p> Signup and view all the answers

    When is chain surveying suitable?

    <p>When the area to be surveyed is small and has simple details</p> Signup and view all the answers

    What is the purpose of tie lines in chain surveying?

    <p>To locate interior details</p> Signup and view all the answers

    What is the temperature of the steel tape in the given example?

    <p>27ºC</p> Signup and view all the answers

    What is the main and longest line in chain surveying called?

    <p>Base line</p> Signup and view all the answers

    What is the coefficient of expansion of steel tapes?

    <p>11.2 × 10−6 per ℃</p> Signup and view all the answers

    What is the difference between the standard temperature and the actual temperature of the tape in the given example?

    <p>7ºC</p> Signup and view all the answers

    What are the points at the beginning and end of the chain line called?

    <p>Survey stations</p> Signup and view all the answers

    What is the line joining the main stations called?

    <p>Controlling line</p> Signup and view all the answers

    What is the symbol used to denote main stations in chain surveying?

    <p>Δ</p> Signup and view all the answers

    What is the purpose of main stations in chain surveying?

    <p>To mark the boundary of the survey</p> Signup and view all the answers

    What is the symbol used to denote subsidiary stations in chain surveying?

    <p>Ο</p> Signup and view all the answers

    Study Notes

    Distance Measurement

    • Distances obtained by pacing are sufficiently accurate for many purposes in surveying, engineering, geology, agriculture, forestry, and military field sketching.

    Measuring Devices

    • Passometer: a small instrument that counts the number of steps automatically in the case of longer distances.
    • Odometer: converts the number of revolutions of a wheel of known circumference to a distance.
    • Measuring Wheel: similar to an odometer, but more portable and self-contained, used to determine distances along irregular or curved lines and boundaries.
    • Laser distance measurement: a method of measuring distances using laser technology.

    Chaining Method

    • Chaining method: an accurate and common method of measuring distances by using a chain or tape.
    • Chains: prepared with several galvanized mild steel wires of different diameters used for linear distance measurement.
    • Tape: a small tool used for measuring distances, prepared from different types of material and performed to various lengths (1m-100m).
    • Types of tapes:
      • Cloth or Linen tape: used for ordinary work, affected by moisture, and not strong.
      • Metallic tape: linen tape reinforced with Brass or Copper wires, durable, and used for all survey works.
      • Steel tape: not used in the field, used for standardizing chains and construction work.
      • Invar tape: made of an alloy of steel and nickel, used at places where maximum precision is required.

    Taping Accessories

    • Inclinometer or clinometer: an instrument used for measuring angles of slope, elevation, or depression of an object with respect to gravity's direction.

    Precautions in Using Instruments in Chaining

    • Clean and dry chains and steel tapes after use in wet weather.
    • Use a piece of colored cloth to enable arrows to be seen clearly on the field.
    • Erect ranging rods as vertically as possible at the exact station point.
    • Indicate the operating tension and temperature for which steel bands/tapes are graduated.
    • Frequently test linen tapes for length and after repairs.
    • Always keep tapes reeled up when not in use.

    Cases for Measurement Distance by Tape

    • Case A: length is less than the tape or chain length for horizontal ground length, easy to measure.
    • Case B: length is more than the tape or chain length, requires ranging rod process.

    Ranging Process

    • Ranging process: the process of establishing intermediate points on a straight line between two endpoints.
    • Direct ranging: done when the two ends of the survey lines are intervisible.

    Mistakes and Errors in Chaining

    • Error: the deviation of the measured value from the "exact" value of a quantity.
    • Types of errors:
      • Instrumental error: tape may differ in actual length from its nominal graduated length due to defects or repairs.
      • Natural errors: the horizontal distance between end graduations of a tape varies due to temperature, wind, and weight.
      • Personal errors: errors made by a surveyor or their equipment.

    Errors in Chaining

    • Errors in the length of tape or chain (Cumulative ±).
    • Sag in the chain or tape (Cumulative +).
    • Non-horizontally of the tape during measurement (Cumulative +).
    • Bad ranging alignment (Cumulative +).
    • Calculate the correct measured distance, assuming the error is evenly distributed throughout the tape.

    Temperature Correction

    • Temperature correction: tapes expand or contract due to temperature variation, causing systematic errors.
    • Invar tape: a nickel-steel alloy with a very low coefficient of expansion, used to minimize temperature errors.
    • Correction formula: Ct = ∝ × L × ∆T

    Chain Survey

    • Chain survey: suitable for surveying small areas with simple details and a fairly flat area, works on the principle of Chain Triangulation.
    • Station In Chain Surveying: survey stations are the points at the beginning and the end of the chain line, including main stations and subsidiary or tie stations.

    Lines In Chain Surveying

    • Base Lines: the main and longest line, which passes approximately through the center of the field.
    • Tie Or Subsidiary Lines: lines that join two tie stations, used to locate interior details, and also called auxiliary lines.

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    Description

    Learn about distance measurement techniques in engineering surveying, including the use of pacing and passometers. Important for surveying, engineering, geology, and more.

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