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Tacheometric Surveying Techniques
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Tacheometric Surveying Techniques

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Questions and Answers

What action should be taken if the images of the two ranging rods do not align?

  • Change the ranging method to indirect.
  • Use a longer surveying rod.
  • Move to a different position.
  • Adjust one of the prisms using a screw. (correct)

    • What condition is necessary for direct ranging to be possible?

  • The survey line must be on flat terrain.
  • Only one person is needed at each point.
  • The first and last points must be intervisible. (correct)
  • The first and last points must be within a chain length.

    • What should the surveyor observe when directing the assistant during direct ranging?

  • Upper portion of the ranging rods.
  • The surrounding landscape.
  • Lower portion of the ranging rods. (correct)
  • Middle portion of the ranging rods.

    • What is the purpose of testing the line ranger for accuracy?

    <p>To ensure both images appear aligned.</p> Signup and view all the answers

    What is the main purpose of ranging in surveying?

    <p>To locate intermediate points on a survey line.</p> Signup and view all the answers

    What is indirect ranging also known as?

    <p>Reciprocal ranging.</p> Signup and view all the answers

    In which scenario would a surveyor typically use indirect ranging?

    <p>When the end points are not intervisible.</p> Signup and view all the answers

    What should a surveyor do to ensure accurate ranging results?

    <p>Regularly test the accuracy of the line ranger.</p> Signup and view all the answers

    Which of the following is a method to easily detect large errors in measurements?

    <p>Carefully targeting objects before taking readings</p> Signup and view all the answers

    What characterizes systematic errors?

    <p>They can be determined by mathematical expressions</p> Signup and view all the answers

    Which of the following examples illustrates a systematic error?

    <p>Measuring with a tape that is too short</p> Signup and view all the answers

    Accidental errors are distinguished by what key feature?

    <p>Their magnitude varies from reading to reading</p> Signup and view all the answers

    What defines cumulative errors in measurements?

    <p>Each measurement adds to the error in the same sense</p> Signup and view all the answers

    Which type of error cannot be estimated using standard functional relations?

    <p>Accidental errors</p> Signup and view all the answers

    What is a common example of an accidental error in surveying?

    <p>Marking the end of a chain length</p> Signup and view all the answers

    Which of the following is NOT considered a source of error in surveying?

    <p>Precision of measurements</p> Signup and view all the answers

    What is the average correction for the first 2000 m length measured with a chain that was found to be 10 cm longer?

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

    If a chain nominally 30 m long is found to be 15 cm longer after measuring 500 m, what is the correction for the measured length?

    <p>2.08 m</p> Signup and view all the answers

    What is the exact length of the whole measurement after measuring a total of 2505.41 m with corrections applied?

    <p>2505.41 m</p> Signup and view all the answers

    What is the correction for a survey line measured at 841.5 m with a 20 m chain that was found to be 0.1 m too long?

    <p>4.21 m</p> Signup and view all the answers

    In which type of surveying is the curvature of the earth considered?

    <p>Geodetic surveying</p> Signup and view all the answers

    What distinguishes precision from accuracy in surveying?

    <p>Precision refers to consistency; accuracy refers to nearness to truth.</p> Signup and view all the answers

    What type of error is characterized by a known cause that allows for correction?

    <p>Systematic error</p> Signup and view all the answers

    The objective of engineering surveying is primarily to collect data for what purpose?

    <p>Designing various infrastructure projects</p> Signup and view all the answers

    What is the primary advantage of using steel tapes over metallic tapes in measuring?

    <p>Higher accuracy</p> Signup and view all the answers

    What materials make up invar tape?

    <p>Nickel and steel</p> Signup and view all the answers

    Which distance option is not available for steel tapes?

    <p>25 m</p> Signup and view all the answers

    What is the purpose of arrows in horizontal measurements?

    <p>To mark end points of chain lengths</p> Signup and view all the answers

    What is a characteristic of invar tape that affects its measurement over time?

    <p>Thermal expansion</p> Signup and view all the answers

    What is the primary purpose of using tacheometric surveys?

    <p>To determine horizontal distance and elevation in difficult terrains</p> Signup and view all the answers

    How long are ranging rods typically?

    <p>2 to 3 m long</p> Signup and view all the answers

    Which type of tacheometric survey is classified into fixed hair and movable hair methods?

    <p>Stadia method</p> Signup and view all the answers

    In which scenario is tacheometric surveying particularly useful?

    <p>In steep and broken ground or deep ravines</p> Signup and view all the answers

    What is the correct section size for wooden pegs used in measuring?

    <p>25 mm x 25 mm</p> Signup and view all the answers

    What instruments are typically used in the stadia method of tacheometry?

    <p>Tacheometer and stadia rod</p> Signup and view all the answers

    What is the visible distance for ranging rods that are well painted?

    <p>Up to 200 m</p> Signup and view all the answers

    What is the significance of the staff intercept in the fixed hair method?

    <p>It is used to calculate the distance from the instrument to the staff station</p> Signup and view all the answers

    Which condition might make ordinary leveling tedious and inaccurate compared to tacheometric surveying?

    <p>Navigating through rough and difficult terrain</p> Signup and view all the answers

    What do U and V represent in the principal equation of the stadia method?

    <p>The distance from the optical center to the staff and the image, respectively</p> Signup and view all the answers

    Which of the following is NOT a typical application of tacheometric surveys?

    <p>Creating thematic maps</p> Signup and view all the answers

    Study Notes

    Tacheometric Surveying

    • Determines horizontal distance and elevation of a point using a known distance and vertical angle.
    • Rapid in rough terrain.
    • Used when obstacles like steep slopes, ravines, and water are present.
    • Creates contour maps.
    • Used in hydrographic, location, road, railway, and reservoir surveys.
    • Used to check other instruments.

    Types of Tacheometric Surveys

    • Stadia method: uses stadia telescope with stadia hairs.
      • Fixed hair method: stadia hair interval is fixed, staff intercept determines distance.
      • Movable hair method: stadia hairs can be adjusted for different distances.
    • Tangential method: uses tangent screws to measure horizontal and vertical angles.
    • Special instruments: like range finders, electronic distance measuring devices (EDM).

    Stadia Method Instruments

    • Tacheometer: transit theodolite with stadia telescope.
    • Stadia rod: rod with markings (5cm to 15cm wide, 3 to 4cm long). Leveling staff can also be used.

    Principle of Stadia Method

    • Optical center of the object glass (O).
    • Stadia lines intersect staff at points A, B, and C.
    • Interval between stadia lines (i).
    • Staff intercept (s, between A and B).
    • Focal length of object glass (F).
    • Horizontal distance from optical center to staff (U).
    • Horizontal distance from optical center to image of staff (V).
    • Horizontal distance from O to vertical axis of tacheometer (D).

    Errors

    • Large errors can be detected by:
      • Carefully targeting objects.
      • Taking multiple readings.
      • Announcing readings loudly for verification.
      • Taking additional readings for checking.
    • Systematic errors: follow a pattern.
    • Accidental Errors: random, cannot be prevented completely.

    Sources of Errors

    • Instrumental errors
    • Natural errors
    • Human limitations

    Steel Tapes

    • 6 to 10 mm wide, with a metal ring at the end.
    • Wound in a leather or metal case.
    • Marked with 5mm, centimeters, decimeters, and meters.
    • Available in 1m, 2m, 10m, 20m, 30m, and 50m lengths.

    Invar Tapes

    • Made of nickel (36%) and steel.
    • Very low coefficient of thermal expansion.
    • Width of 6mm.
    • Available in 30m, 50m, and 100m lengths.
    • Most accurate but expensive.
    • Delicate and should be handled with care.
    • Used for baseline measurements in surveying.

    Accessories for Horizontal Measurements

    • Arrows: Mark end of a chain length.
    • Pegs: Made of wood, used to mark station points.
    • Ranging rods: Used to range intermediate points in measuring.

    Ranging a Survey Line

    • Direct ranging: When endpoints are intervisible. Requires two people.
    • Indirect ranging (reciprocal ranging): When endpoints are not intervisible. Requires more steps to align points.

    Examples of Survey Problems

    • Example 1: Determine exact length of a measured line when a chain is found to be longer at different points.
    • Example 2: Calculate the correct length of a survey line given a chain's nominal length and its actual length.

    Classification of Surveying

    • Engineering surveying: For designing infrastructure projects like roads, railways, irrigation, and sewage systems.

    Solved Question and Answers

    • Difference between Plane Surveying and Geodetic Surveying.
    • Difference between Precision and Accuracy.
    • Difference between Systematic and Random Errors.
    • Difference between Instrumental and Personal Errors.

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    Related Documents

    Basic Surveying PDF

    Description

    Explore the fundamentals of tacheometric surveying, including methods like the stadia and tangential techniques. Learn about the instruments used and the applications of tacheometry in various surveying scenarios. This quiz will test your understanding of how to determine distances and elevations effectively.

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