Questions and Answers
What is a Level Line parallel to?
mean spheroidal surface of earth.
If the R.L. of a B.M. is 100.00 m, the back sight is 1.215 m and the foresight is 1.870 m, what is the R.L. of the forward station?
99.345 m.
What does the rise and fall method provide a check on?
the reduction of intermediate point levels.
How does temperature affect the sensitivity of a bubble tube?
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What does refraction correction partially eliminate?
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What is an imaginary line lying throughout the surface of ground and preserving a constant inclination to the horizontal known as?
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What is the suitable contour interval for a map with scale 1 : 10000?
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What does a series of closely spaced contour lines represent?
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Which method of contouring is the most accurate?
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In direct method of contouring, what is the process of locating or identifying points on a contour called?
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What do closed contours with higher values inwards represent?
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What is contour interval?
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Which errors can be neutralized by setting the level midway between the two stations?
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What is an advantage of the height of instrument method of leveling?
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If the staff is not held vertical at a leveling station, what will the calculated R.L. be?
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How can the sensitivity of a bubble tube be increased?
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What will be the R.L. of point B if the R.L. of point A is 100 m, back sight on A is 2.455 m, and foresight on B is 2.745 m?
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What is an imaginary level surface to which all elevations are measured referred to as?
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What do GTS Benchmarks stand for?
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What is the line of sight defined by the optical centre of the object glass and the centre of the cross bars known as?
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Temporary adjustments of level instrument include ______.
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What technique is used to obtain the heights of points above the line of sight?
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What is the horizontal distance between any two adjacent contours called?
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What method is used for calculating areas assuming the irregular boundary is composed of a series of parabolic arcs?
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What do closed contours of decreasing values towards their centre represent?
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What method can be applied for computation of areas only if the number of ordinates is odd?
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Study Notes
Levelling and Contours
- A Level Line is parallel to the mean spheroidal surface of the Earth, providing a reference for elevation measurements.
- Reducing Levels (R.L) calculations involve back sight and foresight readings to determine the R.L. of different stations, illustrating the application of fore- and backgrounds in surveying.
- The rise and fall method is utilized to check the accuracy of intermediate point level reductions.
Temperature and Sensitivity
- The sensitivity of a bubble tube decreases with rising temperatures, impacting the precision of leveling instruments.
- Increasing the diameter of a bubble tube enhances its sensitivity, affecting measurement accuracy.
Contouring Techniques
- Contour gradients represent imaginary lines on the ground maintaining a constant slope, crucial for understanding terrain changes.
- A suitable contour interval for a map scaled at 1:10,000 is typically 2 meters, aiding visual representation of elevation changes.
- A series of closely spaced contour lines indicates steep slopes, which are essential for terrain evaluation.
Methods of Contouring
- The direct method of contouring is recognized as the most accurate technique for determining elevation points.
- Vertical control in direct contouring identifies points along a contour accurately, ensuring precision in mapping.
- Errors from curvature and refraction can be neutralized by positioning the level instrument midway between two points.
Elevation Measurements
- The R.L. of point B on a ceiling can be determined using foresight and back sight measurements, demonstrating practical applications of leveling.
- Datum describes an imaginary level surface from which all elevation measurements are referenced, critical for establishing uniformity in surveys.
Benchmarking
- GTS Benchmarks are established by the Survey of India, designed with high precision to serve as reference points across the country for surveying tasks.
Line of Sight and Instrument Adjustment
- Height of Collimation refers to the line of sight between the optical center of the object glass and cross bars, affecting measurement accuracy.
- Temporary adjustments needed for leveling instruments include setting up the level, leveling the telescope, and focusing the eye-piece and object glass to ensure clear readings.
Advanced Techniques and Area Calculations
- Inverted Levelling is used to find heights of points above a line of sight, useful in construction and bridge assessments.
- The horizontal distance between adjacent contours is referred to as Contour Equivalent or Horizontal Equivalent, pivotal for understanding terrain layout.
- Simpson's Method provides a higher accuracy for area calculations involving irregular boundaries modeled as parabolic arcs, requiring an odd number of ordinates for effective application.
Closed Contours
- Closed contours with higher values towards the center indicate hillocks, while decreasing values signify depressions or ponds, essential for interpreting natural landforms accurately.
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Description
Test your knowledge on levelling, contours, and calculations of areas and volumes with this quiz. Explore key concepts like level lines, reducing levels, and methods used in surveying. Perfect for students studying surveying or civil engineering.
