Target GATE & ESE 2022 (Geomatics Engineering)

 👉The correct sequence of the survey is

    (a) Traffic survey

    (b) Reconnaissance survey

    (c) Preliminary survey

    (d) Detailed survey or location survey

👉Topographical survey is done to determine information about man made and natural features on earth surface including their elevations.

👉Reconnaissance survey is a kind preliminary survey which is performed to find out method of survey to be adopted and its rough cost.

👉Cadastral survey is done to establish property boundaries.

👉Archaeological survey is done to collect information about old and relic structures.

👉 Transverse surveying is done with the help of compass and chain.

👉Geodetic surveying (Curvature of earth is taken into account) is done with the help of precise instruments such as Theodolite 

👉Weddle sounding machine is used to determine depth of sea in hydrographic surveying.

👉The principal of surveying is work from whole to part.

👉 Various instruments used in surveying and their purpose:

• Pegs: To mark survey station and end points of survey lines on the ground
• Ranging Rod: For locating a number of points on a long survey line
• Offset rods: To set out offset line at right angles
• Prism Square: Setting out right angles
• Clinometer: To measure the slope of ground
• Optical Square: To set out right angles
• Prismatic Square: Advanced version of Optical Square and used to set out right angles
• French Cross Staff: Used to set out either 45 degree or 90 degree
• Open Cross Staff: Type of cross staff which is also used to set out 90 degree
• Theodolite: To measure of all horizontal and vertical angles
• Dumpy Level: Measurement of angle and elevation
• Auto Level: For Levelling purpose

                                                                    Fig 1.  Optical Square

                                                              Fig.2 French Cross Staff

👉Offsets are lateral measurement made w.r.t main survey line which may be oblique or perpendicular in nature.

👉The main objectives of cross staff survey is:

• To locate boundaries of an area
• To plot the figure to a scale
• To find area of the piece of land to be surveyed.  

👉Methods commonly used in reconnaissance surveying for measurement of horizontal distance are:

• Pacing
• Passometer
• Pedometer
• Odometer
• Measuring wheel
• Speedometer
• Perambulator

                                                                  Fig 3. Passometer

  

 Fig 4. Pedometer

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