THEODOLITE SURVEYING 1 - Dronacharya
THEODOLITE SURVEYING1
So far we have been measuring horizontalangles by using a Compass with respect to meridian,which is less accurate and also it is not possible tomeasure vertical angles with a Compass.So when the objects are at a considerabledistance or situated at a considerable elevation ordepression ,it becomes necessary to measure horizontaland vertical angles more precisely. So thesemeasurements are taken by an instrument known as atheodolite.THEODOLITESURVEYING2
THEODOLITE SURVEYINGThe system of surveying in which the angles aremeasured with the help of a theodolite, is calledTheodolite surveying.THEODOLITE SURVEYING3
THEODOLITEThe Theodolite is a most accurate surveyinginstrument mainly used for : Measuring horizontal and vertical angles. Locating points on a line. Prolonging survey lines. Finding difference of level. Setting out grades Ranging curves Tacheometric SurveyTHEODOLITE SURVEYING4
TRANSIT VERNIER THEODOLITETHEODOLITESURVEYINGTHEODOLITESURVEYING5
TRANSIT VERNIER THEODOLITEFig. Details if Upper & Lower Plates.THEODOLITESURVEYINGTHEODOLITESURVEYING6
TRANSIT VERNIER THEODOLITETHEODOLITESURVEYINGTHEODOLITESURVEYING7
CLASSIFICATION OF THEODOLITESTheodolites may be classified as ;A.i) Transit Theodolite.ii) Non Transit Theodolite.B.i) Vernier Theodolites.ii) Micrometer Theodolites.THEODOLITE SURVEYING8
CLASSIFICATION OF THEODOLITESA. Transit Theodolite: A theodolite is called a transittheodolite when its telescope can be transited i.erevolved through a complete revolution about itshorizontal axis in the vertical plane, whereas in aNon-Transit type, the telescope cannot betransited. They are inferior in utility and have nowbecome obsolete.THEODOLITESURVEYING9
CLASSIFICATION OF THEODOLITESB.Vernier Theodolite: For reading the graduatedcircle if verniers are used ,the theodolite is called as aVernier Theodolite.Whereas, if a micrometer is provided to readthe graduated circle the same is called as aMicrometer Theodolite.Vernier type theodolites are commonly used .THEODOLITE SURVEYING10
SIZE OF THEODOLITEA theodolite is designated by diameter of thegraduated circle on the lower plate.The common sizes are 8cm to 12 cm while 14 cm to25 cm instrument are used for triangulation work.Greater accuracy is achieved with largertheodolites as they have bigger graduated circle withlarger divisions hence used where the survey worksrequire high degree of accuracy.THEODOLITE SURVEYING11
DESCRIPTION OF ATRANSIT VERNIER THEODOLITEA Transit vernier theodolite essentially consist of thefollowing :1. Levelling Head.6. T- Frame.2. Lower Circular Plate.7. Plumb –bob.3. Upper Plate.8. Tripod Stand.4. Telescope.5. Vernier Scale.THEODOLITE SURVEYING12
TERMS USED IN MANIPULATING A TRANSIT VERNIER THEODOLITE.1.Centering : Centering means setting thetheodolite exactly over an instrument- stationso that its vertical axis lies immediately abovethe station- mark. It can be done by means ofplumb bob suspended from a small hookattached to the vertical axis of the theodolite.Thecentreshiftingarrangement if provided with the instrumenthelps in easy and rapid performance of thecentring.THEODOLITE SURVEYING13
TERMS USED IN MANIPULATING ATRANSIT VERNIER THEODOLITE.2. Transiting :Transiting is also known as plunging orreversing. It is the process of turning thetelescope about its horizontal axis through 1800in the vertical plane thus bringing it upsidedown and making it point , exactly in oppositedirection.THEODOLITE SURVEYING14
TERMS USED IN MANIPULATING ATRANSIT VERNIER THEODOLITE.3. Swinging the telescopeIt means turning the telescope about itsvertical axis in the horizontal plane.A swing is called right or left according as thetelescope is rotated clockwise or counterclockwise.THEODOLITE SURVEYING15
TERMS USED IN MANIPULATING ATRANSIT VERNIER THEODOLITE.4. Face LeftIf the vertical circle of the instrument is onthe left side of the observer while taking areading ,the position is called the face left andthe observation taken on the horizontal orvertical circle in this position, is known as theface left observationTHEODOLITE SURVEYING16
TERMS USED IN MANIPULATING ATRANSIT VERNIER THEODOLITE.5. Face RightIf the vertical circle of the instrument is onthe right side of the observer while taking areading ,the position is called the face right andthe observation taken on the horizontal orvertical circle in this position, is known as theface right observation.THEODOLITE SURVEYING17
TERMS USED IN MANIPULATING ATRANSIT VERNIER THEODOLITE.6. Changing FaceIt is the operation of bringing the verticalcircle to the right of the observer ,if originally itis to the left , and vice – versa.It is done in two steps; Firstly revolve thetelescope through 1800 in a vertical plane andthen rotate it through 1800 in the horizontalplane i.e first transit the telescope and thenswing it through 1800.THEODOLITE SURVEYING18
TERMS USED IN MANIPULATING ATRANSIT VERNIER THEODOLITE.7. Line of CollimationDIAPHRAGMLINE OFCOLLIMATIONTELESCOPEIt is also known as the line of sight .It is animaginary line joining the intersection of thecross- hairs of the diaphragm to the opticalcentre of the object- glass and its continuation.THEODOLITE SURVEYING19
TERMS USED IN MANIPULATING ATRANSIT VERNIER THEODOLITE.8. Axis of the telescopeOBJECT GLASSAXIS OF THE TELESCOPE.TELESCOPEIt is also known an imaginary line joining theoptical centre of the object- glass to the centreof eye piece.THEODOLITE SURVEYING20
TERMS USED IN MANIPULATING ATRANSIT VERNIER THEODOLITE.9. Axis of the Level TubeIt is also called the bubble line.It is a straight line tangential to the longitudinalcurve of the level tube at the centre of the tube.It is horizontal when the bubble is in the centre.THEODOLITE SURVEYING21
TERMS USED IN MANIPULATING ATRANSIT VERNIER THEODOLITE.10. Vertical AxisIt is the axis about which the telescope can berotated in the horizontal plane.11. Horizontal AxisIt is the axis about which the telescope can berotated in the vertical plane.It is also called the trunion axis.THEODOLITE SURVEYING22
ADJUSTMENT OF A THEODOLITEThe adjustments of a theodolite are of two kinds :1. Permanent Adjustments.2. Temporary Adjustments.1)Permanent adjustments: The permanentadjustments are made to establish the relationshipbetween the fundamental lines of the theodolite and ,once made , they last for a long time. They are essentialfor the accuracy of observations.THEODOLITE SURVEYING23
ADJUSTMENT OF A THEODOLITE1. Permanent adjustments:The permanentadjustments in case of a transit theodolites are :i) Adjustment of Horizontal Plate Levels. The axis ofthe plate levels must be perpendicular to the verticalaxis.ii) Collimation Adjustment. The line of collimationshould coincide with the axis of the telescope andthe axis of the objective slide and should be at rightangles to the horizontal axis.iii) Horizontal axis adjustment. The horizontal axismust be perpendicular to the vertical axis.THEODOLITE SURVEYING24
ADJUSTMENT OF A THEODOLITE1.Permanent adjustments (contd.):iv) Adjustment of Telescope Level or the Altitude LevelPlate Levels. The axis of the telescope levels or thealtitude level must be parallel to the line ofcollimation.v) Vertical Circle Index Adjustment. The verticalcircle vernier must read zero when the line ofcollimation is horizontal.THEODOLITE SURVEYING25
ADJUSTMENT OF A THEODOLITE2.Temporary AdjustmentThe temporary adjustments are made at each setup of the instrument before we start takingobservations with the instrument. There are threetemporary adjustments of a THEODOLITE SURVEYING26
MEASUREMENT OF HORIZONTAL ANGLES:There are three methods of measuring horizontalangles:i)Ordinary Method.ii)Repetition Method.iii)Reiteration Method.THEODOLITE SURVEYING27
MEASUREMENT OF HORIZONTAL ANGLES:i) Ordinary Method. To measure horizontal angle AOB:i) Set up the theodolite at station point OAand level it accurately.Bii) Set the vernier A to the zero or 3600 ofthe horizontal circle. Tighten theupper clamp.iii) Loosen the lower clamp. Turn theinstrument and direct the telescopetowards A to bisect it accurately withthe use oftangent screw. Afterbisecting accurately check the readingwhich must still read zero. Read thevernier B and record both thereadings.THEODOLITE SURVEYINGoHORIZONTAL ANGLE AOB28
MEASUREMENT OF HORIZONTAL ANGLES:i) Ordinary Method. To measure horizontal angle AOB:iv) Loosen the upper clamp and turn thetelescope clockwise until line of sightbisects point B on the right hand side.Then tighten the upper clamp andbisect it accurately by turning itstangent screw.v) Read both verniers. The reading of thevernier a which was initially set atzero gives the value of the angle AOBdirectly and that of the other vernierB by deducting 1800 .The mean of thetwo vernier readings gives the value ofthe required angle AOB.THEODOLITE SURVEYINGABoHORIZONTAL ANGLE AOB29
MEASUREMENT OF HORIZONTAL ANGLES:i) Ordinary Method. To measure horizontal angle AOB:vi) Change the face of the instrumentand repeat the whole process. Themean of the two vernier readings givesthe second value of the angle AOBwhich should be approximately orexactly equal to the previous value.vii) The mean of the two values ofangle AOB ,one with face left andother with face right ,givesrequired angle free frominstrumental errors.THEODOLITE SURVEYINGthethetheallABoHORIZONTAL ANGLE AOB30
MEASUREMENT OF HORIZONTAL ANGLES:ii)Repetition Method.This method is used for very accuratework. In this method ,the same angleis added several times mechanicallyand the correct value of the angle isobtained by dividing the accumulatedreading by the no. of repetitions.The No. of repetitions made usually inthis method is six, three with the faceleft and three with the face right .Inthis way ,angles can be measured to afiner degree of accuracy than thatobtainable with the least count of thevernier.THEODOLITE SURVEYINGABoHORIZONTAL ANGLE AOB31
MEASUREMENT OF HORIZONTAL ANGLES:ii)Repetition Method.To measure horizontalrepetitions:-anglebyABi) Set up the theodolite at starting pointO and level it accurately.ii) Measure The horizontal angle AOB.iii) Loosen the lower clamp and turn thetelescope clock – wise until the object(A) is sighted again. Bisect Baccurately by using the upper tangentscrew. The verniers will now read thetwice the value of the angle now.THEODOLITE SURVEYINGoHORIZONTAL ANGLE AOB32
MEASUREMENT OF HORIZONTAL ANGLES:ii) Repetition Method contd.iv) Repeat the process until the angle isrepeated the required number of times(usually 3). Read again both verniers .The final reading after n repetitionsshould be approximately n X (angle).Divide the sumby the number ofrepetitions and the result thus obtainedgives the correct value of the angle AOB.v)Change the face of the instrument.Repeat exactly in the same manner andfind another value of the angle AOB. Theaverage of tworeadings gives therequired precise value of the angle AOB.THEODOLITE SURVEYINGABoHORIZONTAL ANGLE AOB33
MEASUREMENT OF HORIZONTAL ANGLES:iii) Reiteration Method.This method is another precise andcomparatively less tedious methodof measuring the horizontal angles.ABIt is generally preferred whenseveral angles are to be measuredat a particular station.This method consists in measuringseveral angles successively andfinally closing the horizon at thestarting point. The final reading ofthe vernier A should be same as itsinitial reading.THEODOLITE SURVEYINGCoDReiteration Method34
MEASUREMENT OF HORIZONTAL ANGLES:iii) Reiteration Method. If not ,the discrepancy is equallydistributedamong all themeasured angles.ABProcedureSuppose it is required to measurethe angles AOB,BOC and COD.Then to measure these angles byrepetition method :i) Set up the instrument overstation pointO and level itaccurately.THEODOLITE SURVEYINGCoDReiteration Method35
MEASUREMENT OF HORIZONTAL ANGLES:iii) Reiteration Method.Procedureii) Direct the telescope towardspoint Awhich is known asreferringobject.Bisectitaccurately and check the readingof vernier as 0 or 3600 . Loosen thelower clamp and turn the telescopeclockwise to sight point B exactly.Read the verniers again and Themean reading will give the value ofangle AOB.iii)Similarlybisect C & Dsuccessively, read both verniers at-THEODOLITE SURVEYINGACBoDReiteration Method36
MEASUREMENT OF HORIZONTAL ANGLES:iii) Reiteration Method (contd.).Procedure. each bisection, find thevalue of the angle BOC and COD.iv) Finally close the horizon by sightingtowards the referring object (point A).ABv) The vernier A should now read 3600.If not note down the error .This erroroccurs due to slip etc.vi) If the error is small, it is equallydistributed among the several angles .Iflarge the readings should be discardedand a new set of readings be taken.CoDReiteration MethodTHEODOLITE SURVEYING37
MEASUREMENT OF VERTICAL ANGLES:Vertical Angle : A vertical angle is an angle between theinclined line of sight and the horizontal. It may be anangle of elevation or depression according as the object isabove or below the horizontal plane.AAOB α βOABαHORI. LINEβOβHORI. LINEFig. bFig.aAOB α - βαOHORI. LINEβαFig. cBBVERTICAL ANGLEATHEODOLITE SURVEYING38
MEASUREMENT OF VERTICAL ANGLES:To Measure the Vertical Angle of an object A at a station O:(i) Set up the theodolite at station point O and level itaccurately with reference to the altitude bubble.(ii) Set the zero of vertical vernier exactly to the zero of thevertical circle clamp and tangent screw.(iii) Bring the bubble of the altitude level in the central positionby using clip screw. The line of sight is thus made horizontaland vernier still reads zero.(iv) Loosen the vertical circle clamp screw and direct thetelescope towards the object A and sight it exactly by usingthe vertical circle tangent screw.THEODOLITE SURVEYING39
MEASUREMENT OF VERTICAL ANGLES:(v) Read both verniers on the vertical circle, The mean ofthe two vernier readings gives the value of the requiredangle.(vi) Change the face of the instrument and repeat theprocess. The mean of of the two vernier readings gives thesecond value of the required angle.(vii) The average of the two values of the angles thusobtained, is the required value of the angle free frominstrumental errors.THEODOLITE SURVEYING40
MEASUREMENT OF VERTICAL ANGLES:For measuring Vertical Angle between two points A &Bi) Sight A as before , and take the mean of the two vernierreadings at the vertical circle. Let it be αii) Similarly, sight B and take the mean of the two vernierreadings at the vertical circle. Let it be βiii) The sum or difference of these dings will give the value of thevertical angle between A and B according as one of the points isabove and the other below the horizontal plane. or both pointsare on the same side of the horizontal plane Fig b & cTHEODOLITE SURVEYING41
READING MAGNETIC BEARING OF A LINETo find the bearing of a line AB as shown in fig .belowi) Set up the instrument over A and level it accuratelyii) Set the vernier to the zero of the horizontal circle.Niii) Release the magnetic needle and loosen the . lower clamp.iv) Rotate the instrument till magnetic needlepoints to North. Now clamp the lower clamp withthe help of lower tangent screw .Bring the needleexactly against the mark in order to bring it inmagnetic meridian. At this stage the line of sightwill also be in magnetic meridian.BAFig.Magnetic Bearing of a LineTHEODOLITE SURVEYING42
READING MAGNETIC BEARING OF A LINENow loose the upper clamp and point thetelescope towards B .With the help of uppertangent screw ,bisect B accurately and read boththe verniers .The mean of the two readings will beNrecorded as magnetic bearing of line.iv)BChange the face of the instrumentfor accurate magnetic bearing of theline and repeat .the mean of the twovalues will give the correct bearing ofthe line AB.v)AFig.Magnetic Bearing of a LineTHEODOLITE SURVEYING43
PROLONGING A STRAIGHT A LINEThere are two methods of prolonging a given line such as AB(1) Fore sight method ,and (2) Back Sight Method(1)Fore Sight Method. As shown in the fig. belowABCDZi) Set up the theodolite at A and level it accurately .Bisect thepoint b correctly. Establish a point C in the line beyond Bapproximately by looking over the top of the telescope andaccurately by sighting through the telescope.ii) Shift the instrument to B ,take a fore sight on C and establisha point D in line beyond C.Fig.iii) Repeat the process until the last point Z is reached.THEODOLITE SURVEYING44
PROLONGING A STRAIGHT A LINE(2) Back Sight Method. As shown in the fig. belowABCDZC’D’i)Set up the instrument at B and level it accurately .ii) Take a back sight on A.iii) Tighten the upper and lower clamps, transit the telescopeand establish a point C in the line beyond B.iv) Shift the theodolite to C ,back sight on B transit the telescopeand establish a point D in line beyond C. Repeat the processuntil the last point ( Z) is established.THEODOLITE SURVEYING45
PROLONGING A STRAIGHT A LINE(2) Back Sight Method.(contd.) As shown in the fig. belowABCDZC’D’Now if the instrument is in adjustment, the pointsA,B,C,D and Z will be in one line, which is straight but ifit is not in adjustment i.e. line of collimation is notperpendicular to the horizontal axis ,then C’, D’ and Z’will not be in a straight line.THEODOLITE SURVEYING46
PROLONGING A STRAIGHT A LINEDouble reversing MethodWhen the line is to be prolonged with high precisionor when the instrument is in imperfect adjustment, theprocess of double sighting or double reversing, is used.Suppose the line AB is to be prolonged to a point Z.Procedure: As shown below:C1ABCD1DZC2D2Double Sighting / Reversing MethodTHEODOLITE SURVEYING47
PROLONGING A STRAIGHT A LINEDouble reversing Methodi)Set up the theodolite at B and level it accurately.ii) With the face of instrument left, back sight on A and . clamp both the upper and lower motions.iii) Transit the telescope and set a point C1 ahead in line.C1ABCC2Double Sighting / Reversing MethodTHEODOLITE SURVEYINGD1DZD248
PROLONGING A STRAIGHT A LINEDouble reversing Method (contd.)iv) Loosen the lower clamp ,revolve the telescope in thehorizontal plane and back sight on A .Bisect A exactly byusing the lower clamp and its tangent screw. Now the face ofinstrument is right.v)Transit the telescope and establish a point C2 in linebeside the point C1.C1D1ABCDZC2D2Double Sighting / Reversing MethodTHEODOLITE SURVEYING49
PROLONGING A STRAIGHT A LINEDouble reversing Method (contd.)vi) The exact position of the true point C must be mid-way .between C1 and C2 .vii) Measure C1 C2 and establish a point C exactly mid-way, .which lies on the true prolongation of AB.C1ABCC2D1DZD2Fig. Double Sighting / Reversing MethodTHEODOLITE SURVEYING50
PROLONGING A STRAIGHT A LINEDouble reversing Method (contd.)viii) Shift the instrument to C, double sight on B ,establish the .point D1 and D2 and locate the true point D as before .ix) Continue the process until the last point Z is established.C1ABCC2D1DZD2Double Sighting / Reversing MethodTHEODOLITE SURVEYING51
THEODOLITE SURVEYING THEODOLITE The Theodolite is a most accurate surveying instrument mainly used for : Measuring horizontal and vertical angles. Locating points on a line. Prolonging survey lines. Finding difference of level. Se
Micrometer Theodolite - If a micrometer is provided to read the graduated circle the same is called as a Micrometer Theodolite. Vernier type theodolites are commonly used CLASSIFICATION OF THEODOLITES 5. COMPONENTS OF TRANSIT OR VERNIER THEODOLITE 6. Transit vernier theodolite essentially consist of the following 1. Levelling Head.
Sep 05, 2016 · Engineering Surveying -1 CE212 Compass Surveying Lecture 2016, September 03-04 Muhammad Noman. Compass Surveying Chain surveying can be used when the area to be surveyed is comparatively is
ELECTRICAL MEASUREMENT LAB (EEE-352) 27, Knowledge Park III, Greater Noida, UP Phone No. 0124-2323854-858 Website: gnindia.dronacharya.info . 2 Electrical and Electronics Engineering Department Dronacharya Group of Institutions, Gr. Noida Syllabus Note: Minimum of nine experiments from the following: 1. Calibration of ac voltmeter and ac ammeter
Route Surveying 20 Road Construction Plans and Specifications. 21. Land Surveying Lab 22 Legal Principles of Surveying 23 GPS/GIS Surveying 24 Advanced Surveying Practices 25 Soil Mechanics 26 Concrete and Hot-Mix Asphalt Testing 27. Water and Water Distribution. 28 Spec
1. State the Objectives of Surveying? 2. What is basic principle on which Surveying has been classified? And explain them? 3. Differentiate between Plane Surveying & Geodetic Surveying? 4. State the various types of functional classification of Surveying? 5. State t
SURVEYING LAB II LABORATORY – SYLLABUS Exp. No. Name of Experiments 1. Introduction to Advanced Surveying Laboratory 2. Study of Theodolite in detail-practice for measurement of horizontal and vertical angles 3. Measurement of horizontal angles by method of Repetition and Reiteration
1. Define Surveying. Wha t are the fundamental principles of surveying? Surveying is an art of determining the relative positions of various points on, above or below the surface of the earth by means of direct or indirect measurement of distance, direction and elevation. The principles of
The level of management responsible for developing strategic goals is: A. line B. supervisor C. functional D. senior . D. other organisations that do business with the 14 Where a stakeholder is identified as having high interest and low power, an organisation should: keep them satisfied monitor their interests and power C. manage them closely keep them informed 15. Highfield Aeet 12 .
