JNTU B.Tech II SURVEYING AND OFFSHORE STRUCTURES Previous Question Paper (March - 2022 - R16)

The fundamental principle of surveying is to work from the whole to the part. This involves establishing a system of control points with high precision over a large area first, and then filling in the details using less precise methods. This approach ensures that errors are localized and prevented from accumulating or magnifying across the survey area.

Based on function, surveying is classified into the following types:

• Control Surveying: Used to establish a horizontal and vertical framework of control points to which minor surveys can be referenced.
• Land Surveying: Conducted to determine the boundaries, area, and features of land parcels, often for legal or property purposes.
• Topographical Surveying: Carried out to map the natural and artificial features of the ground, such as hills, rivers, roads, and buildings, to produce a topographical map.
• Engineering Surveying: Performed to provide sufficient data for the design and construction of engineering projects like highways, railways, bridges, and dams.
• Hydrographic Surveying: Deals with bodies of water, mapping shorelines, water depths, and underwater features for navigation and construction.
• Astronomical Surveying: Involves observations of celestial bodies to determine absolute locations and azimuths on the Earth's surface.

Temporary adjustments are those that must be performed at every station where the theodolite is set up before taking any observations. These adjustments include:

1. Setting up: This involves centering the theodolite over the station mark using a tripod and a plumb bob or optical plummet, ensuring the instrument is approximately level.
2. Centering: The process of bringing the vertical axis of the theodolite exactly over the station point. This is achieved by shifting the tripod legs or using the shifting head of the tripod.
3. Leveling: The instrument is leveled using the foot screws to ensure the vertical axis is truly vertical. The plate levels are used for this purpose; the bubble is brought to the center of its run by manipulating the foot screws in a specific sequence.
4. Elimination of Parallax: Parallax occurs when the image formed by the objective lens does not lie in the plane of the crosshairs. It is eliminated by focusing the eyepiece to see the crosshairs clearly and then adjusting the focusing screw to bring the target image into the plane of the crosshairs.