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. Therefore, we know that there is some misclosure error during our leveling fieldwork process. Leveling Rod can be a lot of types. There leveling has two type of layouts which are the rise and fall method and the height of collimation method. It allow us to measure a large elevation vertical distances. The surveyor sets the instrument up quickly and doesn't have to relevel it carefully each time he sights on a rod on another point.
If carefully done, it gives quite accurate results. Week 2 Taping Week 3 Transit and Angles Week 4 Field Survey for Course Project Phase 1 Week 5 Field Survey for Course Project Phase 2 Leveling. It can used in traversing and leveling measurements in fieldworks. The method in Figure 4-3 uses the difference in elevation between a known elevation and the height of the instrument, and then the difference in elevation from the height of instrument to an unknown elevation point. The rod can usually be raised up to 25 feet high, allowing the level to be set much higher than the base of the rod.
Civil Engineering Land Surveying Basics Land Surveying Class Lectures - Survey Class Lecture Notes Free Download The history of surveying started with plane surveying when the first line was measured. Anytime an instrument is dropped or severely bumped, or suspected of the same, it should be checked immediately. It is a self-leveling optical instrument for accurately measuring horizontal planes and angles at long or short distances. Writing is a two-way process. Level surface: A level surface is defined as a curved surface which at each point is perpendicular to the direction of gravity at the point.
Barometric levelling Barometric levelling makes use of the phenomenon that difference in elevation between two points is proportional to the difference in atmospheric pressures at these points. Its very important to understand the difference between the two at the first place, from the definition its pretty clear as to why its done. A person can easily carry it to the field. Types of levels a Tilting — adjustment of level bubble needed before every measurement. After we got our loop misclosure error, we calculate the correction per set up and adjust the initial reduced level to get the final reduced level.
There may be obstructions or large changes of elevation between the endpoints. To be more accurate, we must do two method in a row. Microprocessor unit processes the data collected to compute: 1. The reduced level is being calculated through the two method, which is Rise and Fall Method and Height of Collimation Method. In the real gravity field of the Earth, this happens only approximately; on small loops typical of engineering projects, the loop closure is negligible, but on larger loops covering regions or continents it is not. Before any construction starts its important to make sure the land is in level and doesn't have much difference in gradient. If erratic compensator movement is detected, have a qualified repair shop service the instrument.
Those who do not have any vehicles, for them this is only a piece of information. Surveyors work with elements of geometry,trigonometry, regression analysis, physics,engineering, metrology, programming languages and the law. The introduction Page 1 provides background information to the report, e. Using these values, engineers can study the geological characteristic of the area. The elevation of a point has been defined as its vertical distance above and below a given reference level surface and usually a mean sea level. Do camparison between 2 set of readings 4.
Any information or suggestions about this proposed scheme would be welcome. One of the methods was summing the angles of our triangular stationary points to verify our angles should add up to one-hundred degrees. We will break up into groups later in this lab. There are four main types of reports — 1. This gives the height of the instrument above the starting backsight point and allows the height of the instrument H. Automated data collection eliminates transposition errors and data is downloaded into a computer for complete analysis.
How do I write a report? Bench Mark and Reference Datum In order to calculate the heights of points a datum is required, i. Today the land surveying basics are the same but the instruments and technology has changed. Each line of the level book corresponds to a staff position and this is confirmed by the entrie s in the Rem arks column. In double-levelling, a surveyor takes two foresights and two backsights and makes sure the difference between the foresights and the difference between the backsights are equal, thereby reducing the amount of error. It is used either as a starting point for levelling or as a point upon which to close as a check. Automatic Level is easy to set up and easy to use.
Written for a particular purpose, they usually outline a problem, provide the relevant facts and ideas related to the situation, and then recommend a course of action. For precise leveling networks on a national scale, the latter formula should always be used. Vertical angle: Vertical angle is an angle between two intersecting lines in a vertical plane. It is perpendicular to direction of gravity. This is repeated until the series of measurements is completed. Data collected and processed may be down-loaded to computers for further processing. Raasterization: The process that converts vector data, which is a series of points, lines and polygons into raster data which is a series of cells with a discrete value.
American survey put 250 km2 for treating survey as Plane, but controlling factor should be degree of precision rather than extent of area. We able to done the calculations by using Rise and Fall Method and Height of Collimation Method. The angles measured from the theodolite can be used for working out the coordinates and distance of each station. A level is an instrument with a telescope that can be levelled with a spirit bubble. Rod readings should be taken at equal intervals on both sides of the center line and at significant changes in the terrain. Advantages of Using Total Stations The following are some of the major advantages of using total station over the conventional surveying instruments: 1.