Surveying Techniques Overview

Control Survey

• Definition: Control survey is a surveying method used to establish a network of reference points for mapping or construction, ensuring accurate positioning.

Levelling

• Purpose: To determine the height difference between points.
• Types:
  • Spirit Leveling: Uses a leveling instrument to measure vertical distances.
  • Trigonometric Leveling: Utilizes angles and distances for elevation determination.
• Key Concepts:
  • Benchmark: A reference point with a known elevation.
  • Temporary Benchmarks: Established during surveys for a specific project.

Traversing

• Definition: A method for establishing control points by measuring angles and distances between a series of points.
• Types:
  • Open Traverse: Starts and ends at different points.
  • Closed Traverse: Returns to the starting point, allowing for error checks.
• Key Concepts:
  • Angles: Measured using theodolites or total stations.
  • Coordinates: Calculated for each point based on measurements.

Intersection

• Definition: A technique used to locate a point by observing it from two or more known points.
• Process:
  • Measure angles from the known points to the point of interest.
  • Use geometric methods or trigonometry to determine the unknown point’s position.
• Applications: Useful in areas where direct measurement to the point is not possible.

Resection

• Definition: A method to determine the coordinates of a point by measuring angles to at least two known points.
• Process:
  • Measure angles from the unknown point to known points.
  • Use triangulation or other geometric methods to calculate the unknown point's location.
• Key Concepts:
  • Backsight: The angle measurement to a known point.
  • Fore-sight: The angle measurement to the target point.

Triangulation

• Definition: A surveying method that uses the principles of triangles to determine distances and angles between points.
• Process:
  • Establish a baseline between two control points.
  • Measure angles from both ends of the baseline to the third point.
  • Use trigonometry to calculate distances and locations.
• Key Concepts:
  • Base Line: Known distance between two reference points.
  • Angle of Elevation: The angle between the horizontal plane and the line of sight to a point above the horizontal plane.
• Applications: Effective for large areas where direct measurement is impractical.

Control Survey

• A surveying method to create a network of reference points for accurate mapping and construction, essential for precise positioning.

Levelling

• Purpose is to measure height differences between various points, crucial for creating level surfaces.
• Spirit Leveling: Involves using a leveling instrument to measure vertical distances directly.
• Trigonometric Leveling: Calculates elevation using angles and distances, useful in complex terrains.
• Benchmark: A permanent reference point with a known elevation, essential for consistency.
• Temporary Benchmarks: Established during specific projects for short-term reference.

Traversing

• A technique to establish control points by measuring angles and distances among a series of points.
• Open Traverse: Begins and ends at different locations, often used in preliminary surveys.
• Closed Traverse: Returns to the starting point, allowing for error checks and validations, enhancing reliability.
• Angles: Accurately measured using instruments like theodolites or total stations to ensure precision.
• Coordinates: Derived for each point based on angle and distance measurements, forming a complete mapping.

Intersection

• Allows for locating an unknown point by observing it from two or more known points and measuring angles.
• Involves geometric or trigonometric methods to accurately determine the position of the point of interest.
• Practical in areas where direct measurements are obstructed or infeasible.

Resection

• Determines the coordinates of an unknown point by measuring angles from the known points.
• Utilizes triangulation or geometric methods to calculate the unknown point's position based on back-sight and fore-sight measurements.
• Backsight: The angle directed toward a known point.
• Fore-sight: The angle directed toward the target or unknown point.

Triangulation

• Employs triangular principles to ascertain distances and angles between multiple points.
• Establishes a baseline between two control points for reference.
• Measures angles from each end of the baseline to determine a third point's location, applying trigonometric calculations.
• Base Line: The known distance between two reference points serves as a foundation for triangulation.
• Angle of Elevation: The angle formed between the horizontal plane and the line of sight to an elevated point, significant in determining heights.
• Effective for large regions where direct measurements are challenging or impossible.

This quiz focuses on essential surveying methods such as control surveys, levelling, and traversing. Participants will learn about the purposes, types, and key concepts associated with each technique to enhance their understanding of surveying principles and practices.