surveying iii (topographic and geodetic surveys) - Modern Prepper

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example, a line with an azimuth of 341° 12' 30" falls in the fourth or northwest quadrant and its bearingis N 18° 47' 30 "W.s. Coordinate Computations. If the coordinate of a point and the azimuth and distance from thatpoint to a second point are known, surveyors can compute the coordinate of the second point. Theazimuth and distance from Station A to Station B are determined by measuring the horizontal angle fromthe azimuth mark to Station B and the distance from Station A to Station B.(1) A grid is a rectangular system in which the easting and northing lines form right angles at thepoint of intersection. The computation of the difference in northing (dN)(side Y) and the difference ineasting (dE)(side X) uses the formulas for the computation of a right triangle. The distance from StationA to Station B is the hypotenuse of the triangle, and the bearing angle (azimuth) is the known angle. Thefollowing formulas are used to compute dN and dE:dN = cosine azimuth x distancedE = sine azimuth x distance(2) If the traverse leg falls in the first (northeast) quadrant, the value of the easting increases asthe line goes east, and the value of the northing increases as it goes north. The product of the dE and thedN are positive and are added to the easting and northing of Station A to obtain the coordinate of StationB.(3) When surveyors use calculators with trigonometric functions to compute the traverse, theazimuth is entered and the calculator provides the correct sign of the function, the dN, and the dE. If thefunctions are taken from tables, the computer provides the sign of the function based on the quadrant.Lines going north have positive dNs, and lines going south have negative dNs. Lines going east havepositive dEs, and lines going west have negative dEs. The formulas shown in the following examplesare used to determine the dN and the dE:Example 1: Given an azimuth from Station A to Station B of 70° 15' 15" and a distance of 568.78meters (this falls in the first [northeast] quadrant), compute the dN and the dE.dN = cosine 70° 15' 15" x 568.78 meters= +0.337848 x 568.78 meters = +192.16 metersdE = sine 70° 15' 15" x 568.78 meters= +0.941200 x 568.78 = +535.34 metersExample 2: Given an azimuth from Station B to Station C of 161° 12' 30" and a distance of 548.74meters (this falls in the second [southeast] quadrant), compute the dN and the dE.dN = cosine 161° 12' 30" x 548.74 meters= -0.946696 x 548.74 meters = -519.49 metersEN0593 3-32
dE = sine 161 12' 30" x 548.74 meters= +0.322128 x 548.74 meters = +176.76 metersExample 3: Given an azimuth from Station C to Station A of 294° 40' 45" and a distance of 783.74meters (this falls in the fourth [northwest] quadrant), compute the dN and the dE.dN = cosine 294° 40' 45" x 783.74 meters= 0.417537 x 783.74 = +327.24 metersdE = sine 294 40 '45" x 783.74 meters= -0.908660 x 783.74 meters = -712.15 meterst. Accuracy and Specifications. The overall accuracy of a traverse depends on the equipment, themethods used in the measurements, the accuracy achieved, and the accuracy of the starting and closingdata. An accuracy ratio of 1:5,000 is the minimum accuracy sought in topographic surveying. Inobtaining horizontal distances, an accuracy of at least 2 millimeters per 100 meters must be obtained.When using a 1-second theodolite, surveyors turn the horizontal angles twice in each position (two directand two reverse observations) with an angular closure of 10 seconds per station.u. Linear Error. To determine the acceptability of a traverse, surveyors must compute the linearerror of closure (LEC) (using the Pythagorean theorem), the AE, and the accuracy ratio. The first step ineither case is to determine the linear error in dN and dE. In the case of a loop traverse, the algebraic sumof the dNs should equal zero. Any discrepancy is the linear error in dN. The same is true for dEs.Surveyors then compute the AE using the appropriate accuracy ratio (1:5,000 or better) and the totallength of the traverse. Compare this to the LEC. If the AE is greater than the LEC, the traverse is goodand can be adjusted. If it is not good, it must be redone.v. Accuracy Ratio. The accuracy ratio provides a method of determining the traverse accuracy andcomparing it to established standards. The accuracy ratio is the ratio of the LEC (after it is reduced to acommon ratio and rounded down) to the total length of the traverse. If the accuracy ratio does not fallwithin allowable limits, the traverse must be redone. It is very possible that the measured distances arecorrect and that the error can be attributed to large, compensating angular errors.w. Coordinate Adjustment. Surveyors make adjustments to the traverse using the compass rule.The compass rule states that on any leg of the traverse, corrections to the dN or the dE are alsocorrections to the total correction for the dN or the dE, as the length of the leg is to the total length of thetraverse. The total correction for the dN or the dE is numerically equal to the error in northing (En) orthe error in easting (Ee) but with the opposite sign.3-33 EN0593
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SUBCOURSEEN0593EDITIONAUNITED STATE
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TERMINAL LEARNING OBJECTIVE:ACTION:
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Part G: Adjusting Precise-Positioni
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PART A - FIGURES OF THE EARTH1-1. T
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Figure 1-2. Flattening Fractiona. T
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1-3. Geoid. In geodesy, precise com
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point in the survey to provide the
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one side of a triangle and all of t
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Figure 1-10. Simple Triangulation N
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observation, contains a light sourc
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of a horizontal rod with a small sp
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The Airy theory, announced by G. B.
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Figure 1-15. Products of the Gravim
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a. If the shape of the earth was ex
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Figure 1-16. Single Astronomic Stat
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Figure 1-17. Astro-Geodetic Deflect
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Figure 1-19. Astro-Geodetic Datum O
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(c) The significance of a gravity-o
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absolute deflections of the vertica
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Figure 1-23. Preferred Datumsa. The
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1-17. The World Geodetic System. Be
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Figure 1-25. Using the Same Referen
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LESSON 1PRACTICE EXERCISEThe follow
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12. Which of the following is assum
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LESSON 1PRACTICE EXERCISEANSWER KEY
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THIS PAGE IS INTENTIONALLY LEFT BLA
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for all military and civilian activ
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i. Additional support for other top
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2-7. Status. At present, topographi
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in both. (North American Datum of 1
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water can impede leveling operation
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A field recording booklet. A single
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PART I - OFFICE WORK2-24. General.
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PART J - SURVEY COMMUNICATION2-28.
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length or side is known, and all th
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second-order, Class I net. The leng
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The number of observations required
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to perform the reconnaissance. Fail
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and cultivated, or fields may have
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e an alphanumeric symbol that is st
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2-53. Intervisibility of Stations.
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station is (K/2) 2 x 0.0676, or one
Page 88 and 89: Figure 2-8. Similar Triangles Solut
Page 90 and 91: 2-54. Height of Obstructions. It is
Page 92 and 93: authorized to change the name, it s
Page 94 and 95: Figure 2-12. Cells Connected in Par
Page 96 and 97: added as the cells weaken. Three un
Page 98 and 99: Figure 2-16. Construction Details f
Page 100 and 101: 2-60. Wooden Towers. When it become
Page 102 and 103: LESSON 2PRACTICE EXERCISEThe follow
Page 104 and 105: 11. The face of the 5-inch signal l
Page 106 and 107: LESSON 2PRACTICE EXERCISEANSWER KEY
Page 108 and 109: average line in a triangulation sys
Page 110 and 111: 3-4. Slope Measurements. The slope
Page 112 and 113: strip as close as possible to its f
Page 114 and 115: . Sight along the tops of both of t
Page 116 and 117: Column 1. Record the station number
Page 118 and 119: stake to steady it. With the back o
Page 120 and 121: Figure 3-3. DA Form 4446 (Sample of
Page 122 and 123: micrometer in this optical system i
Page 124 and 125: laterally across the front of the e
Page 126 and 127: Figure 3-7. Horizontal Circle and M
Page 128 and 129: out of adjustment. If the index mar
Page 130 and 131: (1) In order to avoid instrumental
Page 132 and 133: location of the vertical circle on
Page 134 and 135: Figure 3-13. Open Traversec. Closed
Page 136 and 137: designate the exact point of refere
Page 140 and 141: When adjusting a traverse that star
Page 144 and 145: 11. The unit of graduation on a hor
Page 148 and 149: THIS PAGE IS INTENTIONALLY LEFT BLA
Page 150 and 151: differential leveling. The theodoli
Page 152 and 153: additional runs are made due to exc
Page 154 and 155: Figure 4-2. Wild N-3 Precision Leve
Page 156 and 157: (8) Loosen the azimuth clamp (13),
Page 158 and 159: 4.7. Miscellaneous Equipment. In ad
Page 160 and 161: (2) To check for gross errors in th
Page 162 and 163: (a) (1) Begin by completing the inf
Page 164 and 165: Set up and level the instrument. Re
Page 166 and 167: Figure 4-8. Sun and Wind Code(5) Th
Page 168 and 169: (10) Enter the interval between the
Page 170 and 171: Figure 4-9. Closed-Circuit River Cr
Page 172 and 173: Figure 4-11. Sample DA Form 5820 (R
Page 174 and 175: is 0. When the telescope is pointed
Page 176 and 177: stations. However, since all statio
Page 178 and 179: a. Complete the heading, as shown.b
Page 180 and 181: a. (1) Enter the date, as in the sa
Page 184 and 185: 11. The maximum length of site to o
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PART A - GLOBAL POSITIONING SYSTEM
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5-7. Pseudorange. A pseudorange is
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5-15. Number of Pseudorange Observa
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i. Probable Error Measures. The acc
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Table 5-1. Representative GPS Error
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Table 5-2. Carrier Phase Trackinga.
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exercise extreme caution in applyin
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not be designed or performed to ach
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Table 5-3. GPS-S Design, Geometry,
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f. Multiple/Repeat Baseline Connect
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possible ionospheric and tropospher
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Figures 5-4. PDOP Versus Time PlotP
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e. Field Processing and Verificatio
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All carrier phase relative-surveyin
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time spent and the cost of conducti
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movement between occupation sites,
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5-37. General. GPS baseline solutio
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(1) Receiver Time. This technique u
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NOTE: Repeated baselines should be
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5-43. Loop Closure Checks. Postproc
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necessary to determine approximate
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This will ensure that future work w
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may (and usually does) far exceed t
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important in evaluating the overall
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i. Relative GPS baseline standard e
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12. When the networking method is s
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THIS PAGE IS INTENTIONALLY LEFT BLA
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FAR-77 obstructions. Aircraft-movem
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Figure 6-1. Imaginary SurfacesEN059
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Figure 6-3. Approach Surfacesa. Fed
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. Federal Aviation Regulation-77, S
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Table 6-4. Airport Obstruction Accu
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A horizontal scale of 1:12,000 and
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Figure 6-4. Sample DA Form 5821 (Ai
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Figure 6-5. Sample DA Form 5822 (PA
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