Measurements in Surveying
Two kinds of measurements used in plane surveying.
Linear Measurements
- Horizontal distance
- Vertical Distance
Angular Measurements
- Horizontal angle
- Vertical angle
In Surveying all measurements are horizontal, can be inclined; reduce to horizontal and vertical components in plotting. Distance between 2 points on a plan or map is always horizontal distance irrespective of their elevation, (distance between their projection on horizontal plane).
How are these Measured and which instrument should I use?
Distances (Horizontal)
Chaining, Taping (steel tape), tachometry (theodolite), electronic (EDM, GPS)
Angles
Tachometry (theodolite, total station),
Heights
Leveling Equipment (level, theodolite, total station)
Methods For Measuring Distances
Direct Method
By chain or Tape or other Instruments directly. For direct measurement several methods/ Instruments are available e.g.
- Pacing
- Passometer
- Pedometer
- Odometer
- Speedometer
- Perambulator
- Judging distance
- Time Measurement
Chaining and Taping
- Most Common method is the method of measuring distance with a Chain or Tape, Called Chaining.
- For Ordinary work (less Precision) Chain is used.
- For Great Accuracy Steel Tape is used.
- To measure distances with Chain is called Chaining while to measure distances with Tape is called Taping
- Chain is composed of 100-150 pieces of galvanized mild steel called LINKS.
- Links are connected to each other through oval ring for flexibility.
- End Provided with Brass handle to drag chain, Outside of handle is ZERO.
- Length Measured from outside of one handle to outside of other handle.
- Metallic tags are attached to specified distances.
Also See: Types of Chains in Surveying
