Podcast
Questions and Answers
What action should be taken if the images of the two ranging rods do not align?
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?
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?
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?
What is the purpose of testing the line ranger for accuracy?
What is the main purpose of ranging in surveying?
What is the main purpose of ranging in surveying?
What is indirect ranging also known as?
What is indirect ranging also known as?
In which scenario would a surveyor typically use indirect ranging?
In which scenario would a surveyor typically use indirect ranging?
What should a surveyor do to ensure accurate ranging results?
What should a surveyor do to ensure accurate ranging results?
Which of the following is a method to easily detect large errors in measurements?
Which of the following is a method to easily detect large errors in measurements?
What characterizes systematic errors?
What characterizes systematic errors?
Which of the following examples illustrates a systematic error?
Which of the following examples illustrates a systematic error?
Accidental errors are distinguished by what key feature?
Accidental errors are distinguished by what key feature?
What defines cumulative errors in measurements?
What defines cumulative errors in measurements?
Which type of error cannot be estimated using standard functional relations?
Which type of error cannot be estimated using standard functional relations?
What is a common example of an accidental error in surveying?
What is a common example of an accidental error in surveying?
Which of the following is NOT considered a source of error in surveying?
Which of the following is NOT considered a source of error in surveying?
What is the average correction for the first 2000 m length measured with a chain that was found to be 10 cm longer?
What is the average correction for the first 2000 m length measured with a chain that was found to be 10 cm longer?
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?
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?
What is the exact length of the whole measurement after measuring a total of 2505.41 m with corrections applied?
What is the exact length of the whole measurement after measuring a total of 2505.41 m with corrections applied?
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?
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?
In which type of surveying is the curvature of the earth considered?
In which type of surveying is the curvature of the earth considered?
What distinguishes precision from accuracy in surveying?
What distinguishes precision from accuracy in surveying?
What type of error is characterized by a known cause that allows for correction?
What type of error is characterized by a known cause that allows for correction?
The objective of engineering surveying is primarily to collect data for what purpose?
The objective of engineering surveying is primarily to collect data for what purpose?
What is the primary advantage of using steel tapes over metallic tapes in measuring?
What is the primary advantage of using steel tapes over metallic tapes in measuring?
What materials make up invar tape?
What materials make up invar tape?
Which distance option is not available for steel tapes?
Which distance option is not available for steel tapes?
What is the purpose of arrows in horizontal measurements?
What is the purpose of arrows in horizontal measurements?
What is a characteristic of invar tape that affects its measurement over time?
What is a characteristic of invar tape that affects its measurement over time?
What is the primary purpose of using tacheometric surveys?
What is the primary purpose of using tacheometric surveys?
How long are ranging rods typically?
How long are ranging rods typically?
Which type of tacheometric survey is classified into fixed hair and movable hair methods?
Which type of tacheometric survey is classified into fixed hair and movable hair methods?
In which scenario is tacheometric surveying particularly useful?
In which scenario is tacheometric surveying particularly useful?
What is the correct section size for wooden pegs used in measuring?
What is the correct section size for wooden pegs used in measuring?
What instruments are typically used in the stadia method of tacheometry?
What instruments are typically used in the stadia method of tacheometry?
What is the visible distance for ranging rods that are well painted?
What is the visible distance for ranging rods that are well painted?
What is the significance of the staff intercept in the fixed hair method?
What is the significance of the staff intercept in the fixed hair method?
Which condition might make ordinary leveling tedious and inaccurate compared to tacheometric surveying?
Which condition might make ordinary leveling tedious and inaccurate compared to tacheometric surveying?
What do U and V represent in the principal equation of the stadia method?
What do U and V represent in the principal equation of the stadia method?
Which of the following is NOT a typical application of tacheometric surveys?
Which of the following is NOT a typical application of tacheometric surveys?
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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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.
