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O-K-State MCAG 2313 - Distance Measuring

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Distance MeasuringTwo principles of measuring distanceDistanceBest methodExampleBarbed WireWooden PoleFoundationHorizontal & Slope DistanceDifference Between Horizontal and Slope DistanceHorizontal DistanceSlope distanceDetermining Horizontal DistanceUsing Equipment To Measure Horizontal DistanceUsing Equipment To Measure Horizontal Distance--Stadia1/2 StadiaUsing Equipment To Measure Horizontal Distance--(EDM)Calculating Horizontal DistanceCalculating Horizontal Distance --Percent slopeCalculating Horizontal Distance--Difference in ElevationCalculating Horizontal Distance--Vertical AngleQuestions ?Distance MeasuringTwo principles of measuring distance1) It takes two points to form a line. 2) The shortest distance between two points is a straight line.DistanceIn surveying, the term “distance” has two uses. The common use is to measure the displacement (distance) between two or more points. Distance can also be used to define the dimensions of an objectBest methodDetermined by:EnvironmentUse of the dataEquipment availableExpertise of individualsPersonal preferenceTopographyClient specificationsRegulationsStandard practiceThe most important factor is the use of the data.ExampleWhat method should be used to determine the amount of materials needed to build a fence?Barbed WireBarbed wire is usually purchased in rolls that contain 100 rods of wire.Does the precision need to be 1/100’s of a foot? NoWooden PoleHorizontal poles are usually six to eight feet.Is pacing an acceptable method?YesFoundationMeasuring the location of forms for a foundation is a different job.Distances should be measured to 1/8 or 1/4 inch.Horizontal & Slope DistanceHorizontal distance is a distance measured on a horizontal plane.Horizontal distance can also be calculated.Slope distance is a distance measured on a surface that is not a plane.For general surveying the difference between horizontal and slope distance is ignored for slopes less than 5%.Difference Between Horizontal and Slope DistanceThe illustration shows the difference that occurs for a 3% slope.The actual difference in length is: € % Slope =riserun x 100Rise =% slope100 x run = 0.03 x 100 = 3 € a2= b2+c2 b = a2−c2 = 1002−32= 99.95When the slope is 3%, the difference between slope distance and horizontal distance is 0.05 feet per 100 feet.Horizontal DistanceTo measure horizontal distance, the tape must be on a horizontal plane.The earth surface is seldom a horizontal plane.Slope distanceWhen distance is measured on the surface of the ground it is called slope (surface) distance.Determining Horizontal Distance The surveyor has two choices.Use equipment and techniques to measure horizontal distance.Measure slope distance and collect additional information to calculate horizontal distance.Using Equipment To Measure Horizontal DistanceChain, level and plumb bob.Using Equipment To Measure Horizontal Distance--StadiaStadia distance is a horizontal distance because a level instrument is used to collect the data.1/2 StadiaUsing Equipment To Measure Horizontal Distance--(EDM)An EDM measures distance by determining the amount of time required for a signal to leave the instrument, reflect off of the target, or object, and return.If the instrument is level when the measurement is taken, the measurement is horizontal distance.Calculating Horizontal DistanceTo calculate horizontal distance you must know the slope distance and one additional bit of information for each station. Either:% slopeorChange in elevationorVertical angle.Calculating Horizontal Distance --Percent slope € % Slope =RiseRun x 100Rise =% Slope x Run100=2 x 255.30 ft100= 5.11 ft € a2= b2+c2b = a2−c2 = 255.302−5.112 = 255.25 ftCalculating Horizontal Distance--Difference in Elevation € a2= b2+c2b = a2−c2 = 234.52−6.52 = 234.41 ft€ Cosin θ =adjhypadj = Cosin θ x hyp= Cosin 19.2 x 510.17 ft= 0.9444 x 510.17= 481.79 ft Calculating Horizontal Distance--Vertical AngleQuestions


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