Horizontal and Vertical Distance Flashcards
Horizontal Distance
Distance by Measurement
Distance by Mechanical Device
Distance by Electronic Distance Measurement
Distance by Measurement
- Pacing
- Taping
- Tachymetry
Length of step in walking
Pacing
Length of one’s pace
Pace Factor-
Pacing Relative Precision
1/200
Most common method of measuring or laying out of horizontal distances.
Measured by stretching a calibrated tape between two points and reading distance indicated on the tape.
Tape
Relative Precision of Taping
1:1000 to 1:25000
Based on optical geometry
Tacheometry
Determining horizontal distance
Precision depends on instrument, skills of the observer, length to be measured, parallax and refraction
Used in the topographic survey
Stadia Method
Precision of Stadia Method
1/300 and 1/1000
Stadia Method Formula:
D=Ks+C
Where:
K= Stadia Interval Factor (100)
s= stadia interval (upper-lower reading)
C= stadia constant (distance from the center of the instrument to the principal focus) value: 0
How long is Subtense bar
= 2 meters long
Subtense Bar Method
D= (𝑆/2)/tan〖𝛼/2〗
S= 2.0 m
D= 1/tan〖𝛼/2〗 or cot𝛼/2
Distance by Mechanical Device
- By Odometer
- By Measuring Wheel
- Optical Rangefinder
Measuring the number of revolution of the wheel
By Odometer
Odometer Precision
1/200
Similar to odometer except more portable and self
Contained
By Measuring Wheel
Uses single-lens reflex camera
Optical Rangefinder
Precision of Optical Rangefinder
1/50 for distance less than 500 meters
Distance by Electronic Distance Measurement
- Geodimeter
- Tellurometer
Very careful measurement in determining the interval of time between emission and reception of transmitted waves.
Electronic Distance Measurements
Basic Principle: Linear Distance are based time required for radio or light wave to travel from one end of a line to the other.
a. Electro-Optical Instruments
b. Microwave Instruments
Instrument that transmit wavelength within the visible spectrum
Electro-Optical Instruments
- Transmit microwave corresponding to wavelengths of about 1.0 to 8.6 mm.
Microwave Instruments
Projects a pulsating visible light beam to a reflector which returns the light to the instrument.
Geodetic Distance Meter
Utilize a high frequency microwave transmission
distance can be computed on the basis of velocity of radio waves
Tellurometer
Precision of Geodetic Distance Meter:
1/200,000
Precision of Tellumeter:
1/300,000
- surveyor’s or engineer’s tape
- Most common: 30 meter tape
Steel Tapes
- Tapes woven from synthetic materials with strong dimensional stability.
- Use when working on electrical installation
Non-metallic tapes
LIST OF Measuring Tape
SNILFW
1. Steel Tapes
2. Non-metallic tapes
3. Invar Tapes
4. Lovar Tape
5. Fiberglass
6. Wires
Invar Tapes are made of how many percent of alloy nickel?
35%
Invar Tapes are made of how many percent of Steel?
65%
Properties and costs somewhere between the conventional steel tapes and invar tape.
Lovar Tape
Made of fiberglass in a longitudinal and transverse pattern
Fiberglass
Flat steel tape utilized in measuring lengths.
Wires
Measurement directly along the slopes when the ground is of uniform inclination and fairly smooth.
Slope Taping