Surveying

UNIT – II

Chapter - 1

SURVEYING

SURVEYING

Surveying: Surveying is the art of measuring horizontal distances, vertical distances and included angles to determine the relative positions of points on or above or below the Earth's surface. It may be direct or indirect measurement of distances, direction and elevation. Location of surface features is a Horizontal Plane (HP).

Levelling: Levelling is the process of determination of the relative heights of surface features in a Vertical Plane (VP). Surveying and levelling are generally considered as distinct operations. Still, in its comprehensive sense, the term surveying includes levelling.

1. OBJECT OF SURVEYING

1. Object of Surveying

Object of Surveying is to prepare a Plan or Map of the area surveyed, showing all the features.

Plan: A Plan is the representation of the ground and the features upon it in the horizontal plane on a paper to a convenient scale. When the area surveyed is small and the scale used is large, then it is known as Plan. [Scale: 1:100, 1:200, 1:500, etc.]

Examples: Plan of a Building, An Estate Plan, A Street Plan, etc.

Map: When the area surveyed is large and the scale used is small, then it is known as Map. [Scale: 1:10000, 1:100 000, etc.]

Examples: City Map, Map of India, World Map, etc.

Elevation or Section: The vertical plane measurements represented on a paper is known as Elevation or Section. The plans and elevations help to ascertain the extent, shape, position, etc., of an area surveyed.

2. Purposes or Uses of Surveying

1. The plan or map prepared will be useful for the location and to study the feasibility of any  engineering project by a civil engineer, namely, Construction of buildings, Laying of roads, Railway lines, Canal works, Tunnels, Sewer lines, Reservoirs, Dams, Bridges, etc.

2. Data is collected for planning, analysis, design, cost estimation and execution of engineering ...works for effective project management.

3. Volumes of earth work in cutting and embankment may be calculated.

4. The data obtained from surveying is used to prepare the contour map. The representation of the relative heights of objects in a vertical plane is called Contour Map.

5. To establish boundary lines of properties based on available records and demarcate the ownership.