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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 utilised are
• to fix the national and state boundaries;
• to chart coastlines, navigable streams and lakes;
• to execute hydrographic and oceanographic charting and mapping; and
• to prepare topographic map of land surface of the earth.
• 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.
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.
In this branch of surveying, the true shape of the earth is taken into consideration.
This type of surveying is being carried out for highly precise work and is adopted for surveying of large area.
In this method of surveying, the mean surface of the earth is considered to be a plane surface. This type of survey is applicable for small area (less than 200 square kilometer). Thus for most of the Civil Engineering projects, methods of plane surveying are valid.
This course is restricted to the different aspects of plane surveying. Henceforth, in this course work, the word surveying implies plane surveying.
| classifications of Surveying |
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.
• 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.
| Operations in Surveying |
Operations in surveying consists of :
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