CE 2121 Module 1 Explain - Surveying Definitions and Types PDF

DEFINITION of SURVEYING  “Surveying is the art of determining the positions of points on or near the earth’s surface by means of measurements in the three elements of space;...

DEFINITION of SURVEYING  “Surveying is the art of determining the positions of points on or near the earth’s surface by means of measurements in the three elements of space; namely, distance, direction, and elevation.” – Rayner and Schmidt.  “Surveying is the art of measuring horizontal and vertical distances between objects, of measuring angles between lines, of determining the direction of lines, and of establishing points by predetermined angular and linear measurements.” – Davis, Foote, Anderson, and Mikhail.  “Surveying is the art of making such measurements of the relative positions of points on the surface of the earth that, on drawing them to scale, natural and artificial features may be exhibited in their correct horizontal or vertical relationships.” – Clarke.  “Surveying is that branch of applied mathematics which teaches the art of determining area of any portion of the earth’s surface, the length and directions of the boundary lines, the contour of the surface, and of accurately delineating the whole on paper.” – Webster.  “Surveying is the science or art of making such measurements as are necessary to determine the relative position of points above, on, or beneath the surface of the earth, or to establish such points.” –Breed, Hosmer, and Bone.  “Surveying is the science and art of determining relative positions of points above, on, or beneath the surface of the earth, or establishing such points.” – Binker and Wolf. Surveys are divided into two general classifications, plane and geodetic. 1. Plane Surveying- is that type of surveying in which the earth is considered to be a flat surface, and where the distances and areas involved are of limited extent that the exact shape of the earth is disregarded. 2. Geodetic Surveying- are surveys of wide extent which take into account the spheroidal shape of the earth. These surveys employ principles of geodesy, are of Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.  high precision, and related calculations involve the solving spherical trigonometry, calculus, and some applications of the theory of the least squares. TYPES OF SURVEYS 1. Cadastral Surveys – are usually closed surveys which are undertaken in urban and rural locations for the purpose of determining and defining property lines and boundaries, corners, and areas. These surveys are also made to fix the boundaries of municipalities, towns, and provincial jurisdictions. 2. City Surveys – are surveys of the areas in and near a city for the purpose of planning expansions or improvements, locating property lines, fixing reference monuments, determining the physical features and configuration of the land, and preparing maps. 3. Construction Surveys – these are surveys which are undertaken at a construction site to provide data regarding grades, reference lines, dimensions, ground configuration, and the location and elevation of structures which are of concern to engineers, architects, and builders. 4. Forestry Surveys – a type of survey executed in connection with forest management and mensuration, and the production and conservation of forest lands. 5. Hydrographic Surveys – refer to surveying streams, lakes, reservoirs, harbors, oceans, and other bodies of water. These surveys are made to map shore lines, chart the shape of areas underlying water surfaces, and measure the flow of streams. They are general importance in connection with navigation, development of water supply and resources, flood control, irrigation, production of hydroelectric power, subaqueous constructions, and recreation. 6. Industrial Surveys – sometimes known as optical tooling. It refers to the use of surveying techniques in ship building, construction and assembly of aircraft, lay- out and installation of heavy and complex machinery, and in other industries where very accurate dimensional layouts are required. 7. Mine Surveys – are surveys which are performed to determine the position of all underground excavations and surface mine structures, to fix surface boundaries of mining claims, determine geological formations, to calculate excavated volumes, and establish lines and grades for other related mining work. 8. Photogrammetric Surveys – a type of survey which makes use of photographs taken with specially designed cameras either from airplanes or ground stations. Measurements are obtained from the photographs which are used in conjunction with limited ground surveys. Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.  9. Route Surveys – involves the determination of alignment, grades, earthwork quantities, location of natural and artificial objects in connection with the planning, design, and construction of highways, railroads, pipelines, canals, transmission lines, and other linear projects. 10. Topographic Surveys – are those surveys made for determining the shape of the ground, and the location and elevation of natural and artificial features upon it. The features shown include such natural objects as hills, mountains, rivers, lakes, relief of the ground surface, etc; and works of man, such as roads, buildings, ports, towns, municipalities, and bridges. SURVEYING INSTRUMENTS 1. Telescope – The invention of the telescope in 1607 is generally accredited to Lippershey. In 1609, Galileo constructed a refracting telescope for astronomical observations. However, it was only when cross hairs for fixing the line of sight were introduced, that the telescope was used in early surveying instruments. 2. Transit – The invention of transit is accredited to Young and Draper who worked independently from each other sometime in 1830. 3. Plane Table – used in field mapping. It consists of a board attached to a tripod in such a way that it can be leveled or rotated to any desired direction. 4. Vernier – a short auxiliary scale placed alongside the graduated scale of an instrument, by means of which refractional parts of the smallest or least division of the main scale can be determined precisely without having to interpolate. It was invented 1631 by a Frenchman name Pierre Vernier. Surveying instrument employ either a direct or retrograde vernier. 5. Compass – The magnetic compass came into wide use during the 13th century for determining the direction of lines and in calculating angles between lines. It was first Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.  introduced for use in navigation. The compass consists of a magnetized steel needle mounted on a pivot at the center of a graduated circle. The needle continues to point toward magnetic north and gives a reading which is dependent upon the position of the graduated circle. SURVEYING MEASUREMENTS ANGULAR UNITS OF MEASUREMENT  Sexagesimal Units- units of angular measurement are the degree, minute, and second. The unit of angle used in surveying is the degree which is defined as 1/360th of a circle. One degree equals 60 minutes, and 1 minute equals to 60 seconds.  Centesimal Units- many countries in Europe and the Middle East use the centesimal system where grad is the angular unit. The grad is divided into 100 centesimal minutes or 0.9 degrees, and the minute is subdivided into 100 centesimal seconds or 0 degree 00 minute 32.4 seconds. THE CONCEPTS OF MISTAKES, ERRORS, ACCURACY, AND PRECISION. MISTAKES. Are inaccuracies in measurements which occur because some aspect of a surveying operation is performed by the surveyor with carelessness, inattention, poor judgment, and improper execution. Mistakes are also caused by misunderstanding of the problem, inexperience, or indifference of the surveyor. A large mistake is reffered to as a blunder. Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.  ERRORS. An error is defined as the difference between the true value and a measured value of a quantity. It is a deviation of an observation or a calculation from the true value and is often beyond the control of the one performing the operation. TYPES OF ERRORS- 1. Systematic Errors This type of error is one which will always have the same sign and magnitude as long as field conditions remain constant and unchanged. For changing field conditions there is a corresponding change in magnitude of error, however, the sign remains constant. A systematic error will repeat itself in other measurements, still maintaining the same sign, and thus will accumulate. It is for this reason that this type of error is also called a cumulative error. 2. Accidental Errors These errors are purely accidental in character. The occurrence of such errors are matters of chance as they are likely to be positive or negative, and may tend in part to compensate or average out according to laws of probability. There is no absolute way of determining or eliminating them since the error for an observation of a quantity is not likely to be the same as for a second observation. ACCURACY. Indicates how close a given measurement is to the absolute or true value of the quantity measured. It implies the closeness between related measurements and their expectations. The difference between the measured value of a quantity and its actual value represents the total error in the measurement. As the measured value approaches the actual value, the magnitude of the error becomes smaller and smaller; and as the magnitude of the total error is decreased, the accuracy of the measurement increases. Therefore, a measurement is termed less accurate if it deviates by a significant amount from its expected value, and it is more accurate if the deviation is relatively small. PRECISION. Precision refers to the degree of refinement and consistency with which any physical measurement is made. It is portrayed by the closeness to one another of a set of repeated measurements of a quantity. Thus, if a set of observations is closely clustered together, the observation is said to have been obtained with high precision. Since precision relates to the expertness of manipulation on the part of the observer or to the capabilities of the instrument used, it requires the use of precise instruments under ideal conditions employing the best techniques. Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document, without the prior written permission of SLU, is strictly prohibited.