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Civil Drafting Technology. Chapter 6 Surveying Fundamentals. Figure 6 – 1: The diameter of the earth measured through the poles is approximately 27 miles less than the diameter measured at the equator.
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Civil Drafting Technology Chapter 6 Surveying Fundamentals
Figure 6–1: The diameter of the earth measured through the poles is approximately 27 miles less than the diameter measured at the equator.
Figure 6–2: The lengths of a 36-mile arc and a chord connecting the arc’s ends vary by only 0.66 ft.
Figure 6–3: A horizontal plane is only 0.66 ft above the earth’s surface at the end of a 1-mile arc.
Figure 6–4: Typical land survey of a subdivision. (Courtesy of Otak, Inc.)
Figure 6–5: A topographic survey is used to compile the information needed to create this topographic map. (Reproduced by permission of the U.S. Geological Survey)
Figure 6–6: A geodetic survey defines major control points that can be used for smaller surveys. (Courtesy of National Geodetic Survey)
Figure 6–7a: This type of aerial photograph has a small scale of 1” = 1700’ and would be used for project plan overview and preliminary studies. (Courtesy of Spencer B. Gross, Inc., Portland, Oregon)
Figure 6–7b: This photo has a larger scale of 1” = 850’ and would be used for preliminary studies, map design, and GIS applications. (Courtesy of Spencer B. Gross, Inc., Portland, Oregon)
Figure 6–7c: This type of 1” = 170’ large-scale photo would be used for engineering and design work. (Courtesy of Spencer B. Gross, Inc., Portland, Oregon)
Figure 6–8: Specialized 3D stereoscopic mapping workstations and eyewear enable the CAD operator to work in a 3D environment.
Figure 6–10: A route survey or an open traverse does not close on itself.
Figure 6–11: Construction survey showing locations of corners and staking out of house with angles and distances.
Figure 6–12: An open traverse does not begin or end at a control point and cannot be easily checked.
Figure 6–13: A connecting traverse is one in which the beginning and end points are known.
Figure 6–14: A loop traverse closes on itself and can be checked easily.
Figure 6–15a: The robotic total station combines vertical and horizontal angle measurements with an EDM. (Courtesy of Trimble Navigation)
Figure 6–15b: A surveyor uses a control unit to operate the total station. (Courtesy of Trimble Navigation)
Figure 6–15c: A GPS receiver is mounted on top of a tracking target to provide accurate GPS data in addition to the measurements taken by the total station. (Courtesy of Trimble Navigation)
Figure 6–15d: Data recorded in an electronic total station can be saved in an electronic data collector. (Courtersy of lopcon Positioning Systems, Inc.)
Figure 6–17: The foresight is measured by turning the instrument clockwise from the backsight in an angles-tothe- right survey.
Figure 6–18: An azimuth traverse measures each angle clockwise from north or south.
Figure 6–19: A topographic map showing State Plane coordinates and UTM rectangular coordinates. (Reproduced by permission of the U.S. Geological Survey)
Figure 6–20: This surveyor is using a GNSS receiver and a handheld controller to record and annotate global positioning system data. (Courtesy of Trimble Navigation)
Figure 6–21: An example of a raw data file displayed in the Carlson Survey Edit/Process program. (Courtesy Carlson Software)
Figure 6–22: Surveyors can collect at least five pieces of data for a single point and store this as a text point file in the total station data collector. The text file is then used to generate a digital terrain model.
Figure 6–23: Point files of project features, such as water line connections in a subdivision, can be quickly laid out in the field by surveyors with an electronic robotic total station.
