FUNDAMENTAL CONCEPTS    

 *INTRODUCTION

Surveying is one of the oldest arts practised by man. History reveals that the principles and practises of surveying were used, consciously or unconsciously, even in the primitive ages, albeit in a crude manner. In the past few decades, however, these have become more rational and channelised.

The introduction and practise of surveying is indispensable to all branches of engineering. The training that a student receives, irrespective of his branch of engineering, in the art of observing, recording and computing data, as well as in the study of errors, their causes and effects, directly contribute to his success in other professional courses. He develops inter alia qualities such as self-reliance, initiative and the ability to get along with others. This also helps an engineer get acquainted with the reasonable limits of accuracy and the value of significant figures. A knowledge of the limits of accuracy can best be obtained by making measurements with the surveying equipment employed in practise, as these measurements provide a true concept of the theory of errors. An engineer must also know when to work to thousandths, hundredths or tenths of a metre and what precision in field data is necessary to justify carrying out computations to the desired number of decimal place. With experience, he learns how the funds, equipment, time and personnel available will govern the procedure and the results. Taking field notes under all sorts of field conditions trains a person to become an excellent engineer, capable of exercising independent judgements.

Surveying is of special importance and interest to a civil engineer. Surveys are required prior to and during the planning and construction of buildings, dams, highways, railways, bridges, canals, tunnels, drainage works, water supply and sewerage systems, etc. They may also be required for planning and construction of factories, assembly lines, jigs, fabrications, missile ranges, launch sites and mine shafts. Surveying is the starting point for any project or constructional scheme under consideration. Details of the proposed work are plotted from the field notes. The reliability of the estimation of quantities and the effectiveness of the design depends upon the precision and thoroughness exercised during the survey. 

Today, the art of surveying has become an important profession. An introduction to the principles and practises of surveying is, therefore, desirable as an integral part of engineering education and training, irrespective of the branch of specialisation. A knowledge of surveying trains the ability of engineers to visualise, think logically and pursue the engineering approach It promotes a feeling of confidence, a habit of working in groups, neatness and care in documentation, and begin interpersonal relations by ways of simultaneous and tactful handling of clients. The chapter is intended primarily to introduce the reader with the objects of surveying, and to surveying principles and practices involved. Since a lot of field work is involved in making the measurements of any part of the earth's surface under varied conditions to produce a map or plan, there is all likelihood of error creeping in the observations made. This necessitates to make the reader conversant with the possible errors, their limits and the ways to keep them to a minimum. This also dictates to learn about the accuracy and desired precession of the method based on the instruments used for making the measurements with economy. A detailed classification of survey also follows, for example, plane survey and geodetic survey based on extent of the area to be surveyed and the limitations of the measuring instruments available. Ultimately the measurements made and the information gathered are generally presented graphically in the form of plan or map depending upon the scale of plotting. For a better understanding of the discussion to follow, it becomes important to get acquainted with a few important definitions applied in surveying.