# State the methods of locating contours and explain direct method.

State the methods of locating contours and explain direct method.

Methods of locating contours :-

1) Direct method

2) Indirect method

i) By cross section ii) By Squares (Block Contouring) iii) Tachometric Method

Direct method of contouring:-

In this method of contouring, the contours of required reduced level are plotted on ground itself. The procedure of direct method of contouring is as follows.

1. Set the level instrument at the center O as shown in figure 1 and do all temporary adjustments like levelling and focusing.

2. Take the first reading on bench mark (Reduced Level i.e. R.L. 100 m) as back sight reading (Say 1.200 m), so that R.L. of instrument axis will become 101.200 m.

3. If the contour of 100 m is required to plot, then reading on staff should be 101.200 – 100 = 1.200 m.

4. This reading of 1.200 m is searched in radial directions (say 300 around instrument station O) by looking through telescope of level instrument. Once these points are found out, then they are marked with red coloured pegs.

5. Similarly, to set 99, 98, and 97 m contour, the reading on staff should be 2.2, 3.2 and 4.2 m respectively. These all contours can be searched in same radial directions and then marked with blue, green and yellow coloured pegs respectively.

6. By joining these identical coloured pegs, we get the required contours on ground by this direct method of contouring.

## Related questions

Description : State methods of locating contours and explain any one.

Last Answer : Following are the methods of locating contours 1. Direct Method. 2. Indirect method.  a) By Square / Block Contouring  b) By Cross Section  c) Tacheometric Contouring ... squares are plotted and reduced levels are written at their corners and the contours lines are then interpolated.

Description : Describe the method of locating contours by square method.

Last Answer : 1) The method of square is indirect method of locating contours. 2) The method of squares is used where the area to be surveyed is small and not much undulating. 3) The area to be surveyed ... points are written on the respective corners. 6) The contours are then interpolated between them.

Description : State any four characteristics of contours with sketches.

Last Answer : Characteristics of contours - The characteristics of contours are described in following statements with the help of necessary sketches. 1. All the points on contour line represent same reduced level or equal ... 8. The summit of four ridge lines represents saddle as shown in sketch 8.

Description : In a contour map, if contours are crossing each other, what will be nature of topography? Draw the sketch to support your answer.

Last Answer : If contours are crossing or intersecting each other, then there is overhanging cliff as shown in figure 1 below.

Description : Define the term interpolation of contours.

Last Answer : Interpolation of contours is the process of locating the required contours proportionately between the plotted reduced levels on sheet.

Description : State Direct & indirect method of contouring.Explain tacheometric method.

Last Answer : Method of contouring are: 1.Direct method 2 Indirect methods which include a)by cross section b)by squares c) tachometric contouring method. Tachometric contouring method. 1.This method ... calculated by tacheometry formulae. 4 The survey is plotted and then contour lines are interpolated.

Description : Explain direct method of contouring.

Last Answer : Direct method of contouring - In this method of contouring, the contours of required reduced level are plotted on ground itself. The procedure of direct method of contouring is as follows. ... identical coloured pegs, we get the required contours on ground by this direct method of contouring.

Description : What are the different methods of contouring? Describe any one method along with sketch . Also write the situation where it is suitable

Last Answer : There are two methods of contouring:- 1. Direct Method 2. Indirect Method - a. By squares  b. By cross section  c. By tacheometric Direct method of contouring - In this ... joining these identical coloured pegs, we get the required contours on ground by this direct method of contouring.

Description : State the methods of contour interpolation and explain in brief any one.

Last Answer : Methods of interpolation:- i) By Arithmetic calculations ii) By Estimation iii) By Graphical method i) By Arithmetic Calculation: This is very tedious but accurate method and is used for small areas ... in fig.) may now be pricked through the position of the contour points on line PQ.

Description : State the two methods of setting out curves.

Last Answer : Methods of setting out curves :- 1) Method of offsets or ordinates from the long chord 2) By successive bisection of arcs 3) By offsets from tangents 4) By offsets from chords produced 5) Rankine’s method of tangential angles 6) Two Theodolite method

Description : Define interpolation of contour and state its methods.

Last Answer : The process of spacing the contours proportionately between the ground points is known as “Interpolation of Contours”. The contours may be interpolated by: 1. Estimation 2. Arithmetical calculations. 3. Graphical method.

Description : Compare radiation and intersection methods of plane table surveying on any two parameters.

Last Answer : Radiation method Intersection method 1. It requires the plane table to occupy a single station.  1. This method requires setting the table up at minimum of two stations.  ... for locating inaccessible points by the intersection of the rays drawn from two instruments stations.

Description : Explain the setting of curve by Rankine’s deflection angle method.

Last Answer : Rankine's deflection angle Method:-  1) Set up theodolite at first tangent point, T1 and level it carefully, set the vernier A to 3600 2) bisect the ranging rod at the point of ... . The angle thus obtained will be set on the vernier of the theodolite for setting out the curve.

Description : Explain the procedure of curve setting by method of offsets from long chord

Last Answer : Procedure: 1. Divide the long chord into an even number of equal parts say 8,10,12 etc. 2. Set out the offset as calculated from the formula  and obtain the required points on the ... ED, the offset for the right half of the curve will be the same as those on the left half side.

Description : Explain the method of repetition to measure horizontal angle using transit theodolite.

Last Answer : Procedure: 1 Suppose the angle AOB is to be measured by the repetition process. The theodolite is set over O. The instrument is centered and levelled properly.Vernier A is set at 00 and vernier is at 1800 ... 8 The mean of the two angles obtained from two faces gives the actual angle AOB.

Description : State the errors eliminated by repetition method.

Last Answer : The errors eliminated by repetition method are : 1) Errors due to eccentricity of verniers and centers are eliminated by taking the both vernier readings and averaging them. 2) Errors due to ... bisection of object may compensate each other. 5) Errors due to improper levelling can be minimized

Description : State the procedure of measurement of horizontal angle by repetition method.

Last Answer : The horizontal angle is measured very precisely using method of repetition as follows : 1) Set-up the theodolite over station O and level it properly. 2) Set the vernier A and vernier B at 0°0'0 ... repeat the same procedure. 9) The mean of both angles gives the horizontal angle AOB.

Description : State the procedure for measuring a horizontal angle by method of repetition.

Last Answer : Procedure : 1. Set up the instrument over Q and level it accurately with the telescope in the normal position. 2. Set the vernier A to 360o. Loosen the lower clamp direct the telescope ... final reading by three. 14. By taking average of both the face, horizontal angle PQR is obtained.

Description : Describe any one method of orientation of plane table surveying

Last Answer : Orientation by back sighting method: This method is accurate and is always preferred. Procedure: 1.Suppose A and B are two stations.The plane table is set up over A. The table is leveled by spirit level ... are perfect and needle is exactly at 0-0 , the orientation is said to be perfect.

Description : Give the simplest method of finding the area of zero of a zero circle from manufacturers table.

Last Answer : The area of zero circle can be find out simply by using following formula. A = M x C Where, A = Area of zero circle  M = Multiplier or multiplying constant provided in manufacturers table C = Constant of planimeter provide in manufacturers table

Description : Write principle of stadia method.

Last Answer : Principle of stadia method: The stadia method is based on the principle that the ratio of the perpendicular to the base is constant in similar isosceles triangles. In figure, let two ... stadia interval factor and the constant (f + d) is known as the additive constant of the instrument

Description : Compare theodolite traversing by included angle method with deflection angle method. Which one is suitable?

Last Answer : Sr.No. Included angle method of traversing  Deflection angle method of traversing 1 This method is most suitable for closed traverse. This method is most suitable for open traverse. ... is suitable for long narrow strip like survey of roads, rivers, canals, railways, etc.

Description : Describe the method of setting out simple curve by using the method of offset from long chord with sketch.

Last Answer : Given data: Direction of two straights, chainage of point of intersection, radius of curve. Procedure:  1) Set theodolite over B and measure deflection angle Ф  2) Calculate tangent length by ... equal to tangent length.  4) Divide long chord into even number of equal parts.

Description : Select the correct statement. . A) Contour interval on any map is kept constant. (B) Direct method of contouring is cheaper than indirect method. (C) Intervisibility of points on a contour map cannot be ascertained. (D) Slope of a hill cannot be determined with the help of contours.

Last Answer : (A) Contour interval on any map is kept constant.

Description : In direct method of contouring, the process of locating or identifying points lying on a contour is called (A) Ranging (B) Centring (C) Horizontal control (D) Vertical control

Last Answer : (D) Vertical control

Description : Explain the principle of techeometry with the help of a neat sketch.

Last Answer : Principle of tacheometry is based on principle of similar triangle in which corresponding sides & altitudes are proportional The ratio of distance of base from apex and length of base is always constant. ... S3=f/i=Constant Where f=focal length of objective and i =stadia intercept

Description : Explain the temporary adjustment of theodolite.

Last Answer : Temporary Adjustments: The temporary adjustments have to be carried out at every setup of the instrument before taking observations with the theodolite A)Setting up: 1) Place the instrument ... . The parallax can be removed by the sharp focusing until the image appears sharp and clear.

Description : Give classification of curve and explain any one in detail.

Last Answer : Types of curve : The curve is classified broadly in two categories 1. Horizontal curve - When the points of curve are joined in horizontal plane then it is known as horizontal curve. 2. Vertical ... roadway or railway tracks. Vertical curves are of four types. a) Summit curve b) Valley curve

Description : Explain the procedure adopted with micro optic theodolite to find reduced level.

Last Answer : Procedure adopted with micro optic theodolite to find reduced level: 1) Take out micro optic theodolite from its box and fix it on the tripod over the required station. 2) Carryout the approximate leveling ... book. 10) RLs can be obtained by line of collimation method or Rise and fall method.

Description : Explain principle of tachometry survey.

Last Answer : Principle of tachometry is based on principle of similar triangle in which corresponding sides & altitudes are proportional. The ratio of distance of base from apex and length of base is always Constant.  ... f/i= Multiplying constant. f= Focal length of objective. i= Stadia Intercept.

Description : Explain temporary adjustment required for theodolite.

Last Answer : The temporary adjustments have to be carried out at every set-up of instrument before taking observations with the theodolite. 1) Setting up the theodolite: Setting up of the theodolite includes: a) ... moves up and down. This is affect of parallax. This can be removed with sharp focusing.

Description : Explain application of remote sensing in civil engineering.

Last Answer : Applications of remote sensing - Remote sensing is widely applicable in the following areas. 1. Resource exploration - The underground resources like fossil fuels, mineral and oil deposits can be explored ... features like hill, valley, trees, houses etc. can be determined in highly steep slopes.

Description : Explain the procedure for measuring of vertical angle by using electronic theodolite

Last Answer : Digital Theodolite for measurement of vertical angle. 1)Taking out digital theodolite for box and fix it on tripod over required station. 2) Accurate centering and aapproximate leveling by leg ... gives required vertical angle from zenith point or horizantal plane as per setting of the instrument.

Description : Explain construction and use of ‘one second micro optic theodolite’.

Last Answer : Construction: Micro optical theodolite have optical system build during manufacturing. This optical system faceplates reading of both horizontal and vertical angle precisely. The least count of this ... towers carrying electric cable can be precisely done. For locating alignment of tunnel.

Description : Explain the temporary adjustment of transit theodolite

Last Answer : Temporary adjustment of transit theodolite consists of following steps. 1. Setting up theodolite over a station 2. Levelling up 3. Focusing of eyepiece. 4. Focusing of object glass. ... , direct the telescope towards object and turn the focusing screw until the appears clear and sharp.

Description : Explain the procedure for measurement of vertical angle using digital theodolite

Last Answer : Digital Theodolite for measurement of vertical angle. 1)Taking out digital theodolite for box and fix it on tripod over required station. 2) Accurate centering and aapproximate leveling by leg ... required vertical angle from zenith point or horizantal plane as per setting of the instrument.

Description : Explain the working principal of EDM with a neat sketch.

Last Answer : Let the distance between P and Q be D' which is to be measured. A wave is transmitted from the transmitter at station P' with certain phase angle. . There ... finding the distance, the phase difference between transmitted wave and reflected wave is measured and converted into distance.

Description : Explain the procedure of measurement of deflection angle.

Last Answer : Procedure: 1. The theodolite is set up at B and centered and leveled properly . Vernier A is set at 0 0.and B at 1800 .The lower one is loosened. By turning the telescope the ranging rod at A ... The average angle of two faces is calulated. One half of this angle will be the deflection angle.

Description : Explain the procedure of establishing grade contour on ground.

Last Answer : The grade contour along hill side can be established by following procedure. Suppose a grade contour of 1 in 30 is to be established on ground at an interval of 40 m. The points of grade contour ... joining all the marked points will give us the required grade contour of 1 in 30 accurately

Description : State the function of Anallatic lens..

Last Answer : The function of anallatic lens is to make additive constant zero i.e.(f+d)=0 It simplifies the calculation.

Description : State two advantages of plane table surveying

Last Answer : 1.it is most rapid method of surveying. 2. it is suitable for magnetic areas. 3.The map can be prepared easily ,and does not require greater skill. 4.Irregular objects can be represented ... is less costly. 7 The check lines detects the errors of measurement and plotting on field itself.

Description : What is meant by zero circle? State the advantages of digital planimeter over polar planimeter.

Last Answer : Zero circle:- When the tracing point is moved along a circle without rotation of the wheel i.e. when the wheel slides without any change in reading ,the circle is known as the zero circle or ... are required for area. 3) It gives more accurate reading 4) Less time required for measurement

Description : State the component parts of micro optic theodolite . How it is superior to a transit theodolite. Also write the situation where it is suitable.

Last Answer : Component parts of micro optic theodolite 1) Telescope 2) Magnification with standard eyepiece. 3) Level tube 4) Foot screws. 5) Tribatch & Trivet 6) Optical micrometer 7) Changing nob 8) ... is most suitable 3) This instrument is durable for harsh environments. 4) It is simple in use.

Description : State any four uses of digital theodolite.

Last Answer : The uses of digital theodolite are as follows. 1. To measure horizontal angle vey precisely up to one second. 2. To measure vertical angle accurately up to one second. 3. To set ... reduced levels of ridge and valley lines accurately. 5. To determine horizontal distance more precisely

Description : Define tacheometry. State the principle of tacheometry with sketch.

Last Answer : Tacheometry : It is the branch of angular surveying in which horizontal and vertical distances are determined from instrumental observations only, is known as tacheometry. Principle of tacheometry : ... to corresponding staff intercept remains constant as shown below in figure 3

Description : State any two situations under which tacheometry is preferred.

Last Answer : Tacheometry is preferred in following situations. 1. When horizontal distances can't be measured by chaining on highly uneven ground. 2. When vertical distances or reduced levels can't be measured ... is necessary to fill the details in topographic map and contour map with low degree of precision.

Description : State any four uses of transit theodolite.

Last Answer : Transit theodolite is useful for the following. 1. To measure the horizontal and vertical angles between survey stations. 2. To measure deflection angles between survey lines. 3. To measure horizontal ... tubular compass to it. 6. To prolong or extend the survey line up to required destination.

Description : State the possible error while using planimeter for finding area of an irregular figure.

Last Answer : Possible error while using planimeter for finding area of an irregular figure: 1) Instrumental Error i) Roller of planimeter which must rotate the axis freely and withot vibrations, if not, then ... vi) Error in setting of arm length. vii) Overlapping or repetition in tracing boundary.

Description : State the meaning of degree of curve and long chord.

Last Answer : Degree of curve : The angle subtended at the centre by a standard chord of 30 m length, is known as degree of curve. Long Chord : The straight line joining rear tangent point and forward tangent point is called as long chord of curve.

Description : State the principle of EDM with sketch.

Last Answer : Principle of EDM:- The fig shows a survey line AB, the length D of which is to be measured using EDM equipment placed at ends A. Let a transmitter be placed at A to propagate electromagnetic waves towards B ... measured at A. This will require EDM timing devices with an accuracy of 1 10-9s.