Surveying for Construction

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When using an optical level, the endpoint may be out of the effective range of the instrument. There may be obstructions or large changes of elevation between the endpoints. In these situations, extra setups are needed. Turning is a term used when referring to moving the level to take an elevation shot from a different location. To "turn" the level, one must first take a reading and record the elevation of the point the rod is located on. While the rod is being kept in exactly the same location, the level is moved to a new location where the rod is still visible. A reading is taken from the new location of the level and the height difference is used to find the new elevation of the level gun, which is why this method is referred to as differential levelling. This is repeated until the series of measurements is completed. The level must be horizontal to get a valid measurement. Because of this, if the horizontal crosshair of the instrument is lower than the base of the rod, the surveyor will not be able to sight the rod and get a reading. The rod can usually be raised up to 25 feet (7.6m) high, allowing the level to be set much higher than the base of the rod.

Surveyors must have a thorough knowledge of algebra, basic calculus, geometry, and trigonometry. They must also know the laws that deal with surveys, real property, and contracts. Construction surveying should be done as soon as the land is being acquired and before construction has begun. The primary way of determining one's position on the earth's surface when no known positions are nearby is by astronomic observations. Observations to the sun, moon and stars could all be made using navigational techniques. Once the instrument's position and bearing to a star is determined, the bearing can be transferred to a reference point on the earth. The point can then be used as a base for further observations. Survey-accurate astronomic positions were difficult to observe and calculate and so tended to be a base off which many other measurements were made. Since the advent of the GPS system, astronomic observations are rare as GPS allows adequate positions to be determined over most of the surface of the earth. Survey assistants or chainmen are usually unskilled workers who help the surveyor. They place target reflectors, find old reference marks, and mark points on the ground. The term 'chainman' derives from past use of measuring chains. An assistant would move the far end of the chain under the surveyor's direction. The mathematician Liu Hui described ways of measuring distant objects in his work Haidao Suanjing or The Sea Island Mathematical Manual, published in 263 AD.The principle of plane table survey is parallelism. They are plotted directly on paper with their relative position. The rays are drawn from station to object on ground. The table is placed at each of the successive station parallel to the position of the last station. If you have an existing degree in another subject, you may be able to take an accredited postgraduate qualification in surveying. The clear and methodical nature of the explanations, supported by a wide range of exercises and examples, make Surveying for Construction 5e an invaluable and modern introduction to surveying. to use that information for the planning and efficient administration of the land, the sea and any structures thereon; and, New Learning Objectives and Chapter Summaries which guide the student through the learning process and highlight the key principles and methods for each chapter

Work experience is essential to gaining employment within the construction industry. You could gain this at school, or by working weekends and holidays with a company or relative who works as a surveyor. Potential employers will always be pleased to see work experience listed on your CV.

This usually relies on a coordinate system selected specifically for the project. How long has construction surveying been around for? Besides this, other such surveys can include perimeter measurements and calculations for foundations, retaining walls, and other items that are necessary to maintain buildings in good conditions. Geodetic survey is conducted by survey department of the country. It is that type of surveying in which the curved shape of the earth is taken in to account. The object of geodetic survey is to determine the precise position on the surface of the earth, of a system of widely distant points which form control stations in which surveys of less precision may be referred. . Line joining two points is considered as curved line and angles are assumed as spherical angles. It is carried out if the area exceeds over 250 km 2. They are basically suitable for filling interior detailing and is recommended when great accuracy is not required. Offsetting is an alternate method of determining the position of objects, and was often used to measure imprecise features such as riverbanks. The surveyor would mark and measure two known positions on the ground roughly parallel to the feature, and mark out a baseline between them. At regular intervals, a distance was measured at right angles from the first line to the feature. The measurements could then be plotted on a plan or map, and the points at the ends of the offset lines could be joined to show the feature.