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Levelling

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Introduction: Levelling is a means by which surveyors can determine the elevation of points, using other known points as references. Levelling is perhaps the most basic of surveying operations and forms an important fundamental part of almost every surveying project. Equipment: Levelling is carried out by the use of: a Spirit Level, often called an Engineer’s Level, and a level rod. The level rod resembles a large fold-up ruler but is not accurately referred to as such. Basics of Levelling : In levelling, the surveyor looks back (BS) to a point of known elevation to determine the elevation of his or her instrument (EI). The surveyor then looks forward (FS) to a point of unknown elevation and determines the elevation of that point using the elevation of his or her instrument (EI) and the value on the level rod read through the level’s telescope. Once the elevation of a point is determined, that point can be used for determining the elevations of other points. In
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Object and uses of Surveying

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As stated in the definition, object of surveying is to show relative positions of various objects of an area on paper and produce plan or map of that area. Various uses of surveying are listed below: (i) Plans prepared to record property lines of private, public and government lands help in avoiding unnecessary controversies. (ii) Maps prepared for marking boundaries of countries, states, districts etc., avoid disputes. (iii) Locality plans help in identifying location of houses and offices in the area. (iv) Road maps help travellers and tourist. (v) Topographic maps showing natural features like rivers, streams, hills, forests help in planning irrigation projects and flood control measures. (vi) For planning and estimating project works like roads, bridges, railways, airports, water supply and waste water disposal surveying is required. (vii) Marine and hydrographic survey helps in planning navigation routes and harbours. (viii) Military survey i
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Levelling Procedures

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a)  Setting up :  Backsight and foresight distances should be approximately equal to avoid any errors due to collimation, refraction or earth curvature.  Distances must not be so great as to not be able to read the graduations accurately.  The points to be observed must be below the level of the instrument, but not lower than the height of the staff. (b)  Elimination of parallax : Parallax is the apparent movement of the image produced by movement of the observer's eye at the eyepiece. It is eliminated by focusing the telescope on infinity and then adjusting the eyepiece until the cross-hairs appear in sharp focus. The setting will remain constant for a particular observer's eye. (c)  Booking :  level books or loose-leaf levelling sheets shall be numbered and indexed in a register.   details of the site, work, date, observer, chainman, booker, weather, wind, instrument and any other relevant items shall be entered.  enter the first observatio
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Equipment

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The level, its tripod, the staff and the staff bubble are all precision items of equipment upon which the accuracy of the work is highly dependent. They shall be kept correctly calibrated, and be used and stored with care. Levels shall be carried in vehicles in a padded box, case or shelf in addition to the normal case, and staves shall be kept in a canvas or plastic sleeve to prevent damage to the face and entry of dirt. Levels A level is basically a telescope attached to an accurate levelling device, set upon a tripod so that it can rotate horizontally through 360° . Normally the levelling device is a bubble, but modern ones incorporate a pendulum. There are three basic types of level, shown in figure 6.1 (from MWD, 1981)and described below: (a)  Dumpy levels: These are more basic levels often used in construction work. The telescope is rigidly attached to a single bubble and the assembly is adjusted either by means of a screwed ball-joint or by footscrews which are ad
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Introduction of Surveying and Levelling

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General : The primary reference at water-level recording stations is a set of stable bench-marks, installed in locations where their level should not change. Upon initial set-up of a station, the levels of the relevant parts of the installation are established and recorded by means of accurate levelling. At least every two years, the levels of the staff gauges, sensor level, internal gauge, tower structure and benchmarks should be measured relative to each other as a check that records are not in error due to bank subsidence or other movement. Accurate levelling is thus a particularly important part of site establishment, installation and quality assurance. All staff shall be thoroughly familiar with its theory and practice. Levelling and surveying methods are also used for measurements of river channel and lake configurations. Often, less accurate methods can be used for this work than for water-level recording stations, although the techniques are common. Definitions : Diffe
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Impact of Infrastructural Development on the Economy of the Country

Civil engineering activities in the infrastructural development are: (i) Good planning of towns and extension areas in the cities. Each extension area should be self sufficient in accommodating offices, educational institutions, markets, hospitals, recreational facilities and residential accommodation. (ii) Assured water supply. (iii) A good drainage system. (iv) Pollution free environmental conditions. (v) A well planned and built network of roads and road crossings. (vi) Railways connections to all important cities and towns. (vii) Airports and harbours of national and international standards. Infrastructure also involves electricity supply, without assured electric supply no city town can develop. Internet and telephones are also desirable features. Educational facility also forms part of infrastructure. Proximity of good primary and secondary schools to residential areas is desirable. Collegiate and professional education also form part of infrastructure of a city
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Importance of Planning, Scheduling and Construction Management

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Introduction: Planning, Scheduling and Management form the basis for any construction activity. Though discussion here is about construction, the same principles hold good for any organisation. Planning is the decision-making process about What, Where, Who and How (WWWH) to start a project. What: An individual or a group of enterprising people plan to start a project. They form a group of high level managers. They identify goals, frame the objective and identify opportunities. The planning done by them may be called as strategic planning. Where: The strategic planners decide the lime and the place of starting the organisation. Who: The strategic planners identify the middle level managers and operational level planners to carry out the task. The middle level management deals with financial management and coordinates with operational planners and strategic planners. How: The operational planners have to work at minute details of the work assigned, find the requirement
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