SURVEYING: SURVEYING DEFINITION OF SURVEYING: DEFINITION OF SURVEYING Surveying is defined as the science of making measurements of the earth specifically the surface of the earth. This is being carried out by finding the spatial location (relative / absolute) of points on or near the surface of the earth. Different methods and instruments are being used to facilitate the work of surveying. The primary aims of field surveying are : - to measure the Horizontal Distance between points. - to measure the Vertical elevation between points. - to find out the Relative direction of lines by measuring horizontal angles with reference to any arbitrary direction and - to find out Absolute direction by measuring horizontal angles with reference to a fixed direction . -These parameters are utilized to find out the relative or absolute coordinates of a point / location. IMPORTANCE OF SURVEYING TO ENGINEERS: IMPORTANCE OF SURVEYING TO ENGINEERS The planning and design of all Civil Engineering projects such as construction of highways, bridges, tunnels, dams etc are based upon surveying measurements. Moreover, during execution, project of any magnitude is constructed along the lines and points established by surveying. Thus, surveying is a basic requirement for all Civil Engineering projects. Other principal works in which surveying is primarily utilized are -to fix the national and state boundaries; -to chart coastlines, navigable streams and lakes; -to establish control points; -to execute hydrographic and oceanographic charting and mapping; and -to prepare topographic map of land surface of the earth. OBJECTIVES OF SURVEYING: OBJECTIVES OF SURVEYING • To collect field data. • To prepare plan or map of the area surveyed, • To analyse and to calculate the field parameters for setting out operation of actual engineering works. • To set out field parameters at the site for further engineering works. DIVISIONS OF SURVEYING: DIVISIONS OF SURVEYING The approximate shape of the earth can best be defined as an oblate tri-axial ovaloid. But, most of the civil engineering works, concern only with a small portion of the earth which seems to be a plane surface. Thus, based upon the consideration of the shape of the earth, surveying is broadly divided into two types. -Geodetic Surveying -Plane Surveying PowerPoint Presentation: Plane Surveys: -are made to locate precisely the points for horizontal control. -cover limited areas and disregard the earth’s curvature. - are conducted by means of a plane table. -are used to locate ground points for aerial photography. -The type of surveying in which the mean surface of the earth is considered as a plane, or in which its spherical shape is neglected, with regard to horizontal distances and directions. FUNDAMENTALS OF PLANE SURVEYING: FUNDAMENTALS OF PLANE SURVEYING • All distances and directions are horizontal; • The direction of the plumb line is same at all points within the limits of the survey; • All angles (both horizontal and vertical) are plane angles ; • Elevations are with reference to a datum. PowerPoint Presentation: Geodetic Surveys: -are conducted from an aero plane for the purpose of mapping. -involve large areas and take the earth’s curvature into account. -are made with the surveyor’s compass. -are a type of hydrographic survey. -The type of surveying that takes into account the true shape of the earth. -These surveys are of high precision and extend over large areas. CLASSIFICATION OF SURVEYS: CLASSIFICATION OF SURVEYS Based on the purpose (for which surveying is being conducted), Surveying has been classified into: • Control surveying : To establish horizontal and vertical positions of control points. • Land surveying : To determine the boundaries and areas of parcels of land, also known as property survey, boundary survey or cadastral survey. • Topographic survey : To prepare a plan/ map of a region which includes natural as well as and man-made features including elevation. • Engineering survey : To collect requisite data for planning, design and execution of engineering projects. Three broad steps are 1 ) Reconnaissance survey : To explore site conditions and availability of infrastructures. 2 ) Preliminary survey : To collect adequate data to prepare plan / map of area to be used for planning and design. 3 ) Location survey : To set out work on the ground for actual construction / execution of the project. PowerPoint Presentation: • Route survey : To plan, design, and laying out of route such as highways, railways, canals, pipelines, and other linear projects. • Construction surveys : Surveys which are required for establishment of points, lines, grades, and for staking out engineering works (after the plans have been prepared and the structural design has been done). • Astronomic surveys : To determine the latitude, longitude (of the observation station) and azimuth (of a line through observation station) from astronomical observation. • Mine surveys : To carry out surveying specific for opencast and underground mining purposes.