Survey Notes Civil Engineering Sem1 1a5x3p
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Department of Civil Engineering Surveying-I (2 marks and 16 marks question and answers)
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UNIT I 1.
INTRODUCTION AND CHAIN SURVEYING Define Surveying. What are the fundamental principals 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 principals of surveying are: (i) Working from whole to part. (ii) To locate a new station by at least two measurements (angular, linear) from fixed reference points.
2.
What is the object or purpose of surveying?
The primary object of surveying is to prepare a plan or map to show the relative position of the objects on the surface of the earth. It is also used to determine the areas, volumes and other related quantities.
3.
Name the different ways of classification of surveys. a. Primary classification (i) (ii)
Plane surveying Geodetic surveying
b. Secondary classification (i) (ii) (iii) (iv)
4.
Based on instruments used Based on methods Based on object Based on nature of the field
Differentiate between plane and geodetic surveying.
Sl.No . 1.
Plane surveying
Geodetic surveying
The curvature of the earth is neglected.
The curvature of the earth is taken.
2.
A line ing any two points is considered straight.
A line ing any two points is considered as curved line.
3.
The triangle formed by any three points is considered as plane triangle.
The triangle formed by any three points is considered as spherical triangle.
4.
It is done on a area less than 250 Km2
It is done on a area greater than 250 Km2
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5.
Classify surveying based on the equipments. 1. Chain surveying 2. Com surveying 3. Plane table surveying 4. Theodolite surveying 5. Tachometric surveying 6. Photogram metric surveying 7. Aerial surveying
6.
Explain the constructions of a diagonal scale.
For a given short length (PQ=PR), draw a right angle triangle. Its base (PR) and height (PQ) are equal. A short length is divided into a number of parts by using the principle of similar triangles in which like sides are proportional. Thus, 1-1 represents 1/10 PQ 9-9 represents 9/10 PQ
7. Define chain surveying. What is the fundamental principle of chain surveying? Chain surveying is the type of surveying in which only linear measurements are made in the field. The main principle of chain surveying or chain triangulation is to provide a framework consist of number of well-conditioned triangles or nearly equilateral triangles. It is used to find the area of the field.
8.
What is well-conditioned triangle? What are its specific advantages?
A triangle is said to be well-conditioned or well proportioned when it contains no angle smaller than 300 and no angle greater then 1200. The main principle of chain surveying is chain triangulation. It consists of frame work of triangles. To plot the network of triangles accurately, the triangles must be
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nearly equal to equilateral or well-conditioned. The distortion due to errors in measurement and plotting should be minimum.
9.
What are the operations involved in chain survey? a. (i) Ranging :The process of locating intermediate points on a straight line between two end points in a straight line. b. (ii) Chaining :The process of measuring the distance with a chain or tape. c. (iii) Offsetting : The process of measuring the lateral distance of the object from the survey line to the left or right according to their positions.
10. What are the instruments required for a chain survey? Chain or tape, Arrows, Pegs, Ranging rods, Offset rods, Laths or whites, Plumb bob, Cross staff and Mallet.
11. Write the different types of Chain. (i) Metric chain (ii) Non-Metric chain
(a) (b) (c) (d)
Gunter's chain or Surveyor's chain Engineer's chain Revenue chain Steel band.
12. Differentiate between Gunter's chain and Engineer's Chain Sl.No. 1.
2.
Gunter's chain or Surveyor's chain It is 66 feet long and divided in to 100 links. 1 link = 0.66 feet Measurements are in miles and furlongs .
Engineer's Chain It is 66 feet long and divided in to 100 links. 1 link = 1 feet. Measurements are in feet and decimals.
13. Define : (a) Main stations. Main station is a prominent point on the chain line and can be either at the beginning of the chain line or at the end or along the boundary. (b) Subsidiary stations : The stations located on the main survey lines are known as Subsidiary stations. (c) Tie stations : These are also subsidiary stations taken on the main survey lines to locate the details of the object.
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www.studentskey.in 14. Draw a neat sketch to show : Base line, Check line, Tie line, offset.
1.
Base line.
2. Check line, 3. Tie line.
4. offset.
15. Distinguish between a check line and a tie line.
16. What are the instruments used for setting out right angles to a chain line ? (i)
Cross staff. a. Open cross staff b. French cross staff c. Adjustable cross staff
(ii) Optical square. (iii) Prism square (iv) Site square.
17. What are offsets ? Classify them. An offset is the lateral distance of an object or ground feature measured from a survey line. The two types of offsets are.
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(i)
Perpendicular offset : The angle of offset from a point on a chain line is
(ii)
Oblique offset : When the angle of offset is other than 900.
900.
Perpendicular offset
Oblique offset
18. What is the use of a line Ranger ? The line Ranger is a small reflecting instrument used for fixing intermediate points on the chain lines. Without going to either end, we can fix the intermediate points.
19. What are the stages of fieldwork in chain surveying ? Or What are the steps involved in chain survey ? 1. Reconnaissance : It is the preliminary inspection of the area to be surveyed. 2. Marking and fixing Survey lines. 3. Running Survey lines. 4. Taking Offsets.
20. Sketch the conventional signs to represent the following : Wall with gate, Railway single line, pond, wire fencing. Object Wall with gate Railway single line Pond Wire fencing
Conventional signs
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www.studentskey.in 21. What are the different tape corrections ? 1. 2. 3. 4. 5.
Correction for absolute length or standardization. Correction for temperature. Correction for pull or tension. Correction for sag. (-ve) Correction for slope. (-ve)
22. What are the errors in chaining ? (i) Compensating Errors : Which are liable to occur in either direction and tend to compensate. (ii) Cumulative Errors : Which occur in the same direction and tend to add or subtract. It may be positive (measured lengths more than the actual length) or negative (measured lengths less than the actual length)
23. What are the different sources of errors in chain surveying ? (i)
Instrumental errors : incorrect length of the chain (Cumulative Errors).
(ii)
Personal error : Bad ranging (Cumulative Errors). Careless holding (Compensating Errors). Non-horizontality (Cumulative Errors). Sag in chain (Cumulative Errors). Miscounting and misreading and booking.
(iii) Natural Errors : Variation in temperature. (Cumulative Errors).
24. Enumerate the instruments used for measurement of lengths of survey lines. (i) (ii) (iii) (iv)
Chain or tape. ometer. Pedometer Odometer Speedometer.
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UNIT II COM SURVEYING AND PLANE TABLE SURVEYING 1.
Define :Com surveying. What are the objects of com surveying ?
Com surveying is the type of surveying in which the direction of the survey lines are measured with a com and the length of the survey lines are measured with a tape or chain in the field.
2.
Write the means of the instruments used in chain surveying. (i)
(ii)
3.
Instruments for the direct measurement of directions : 1. Surveyor's com. 2. Prismatic com. Instruments for the measurement of angles : 1. Sextant. 2. Theodolite
Define : (a).
True meridian, magnetic and bearing.
True meridian : The line or plane ing through the geographical North Pole, South Pole and any point on the surface of the earth, is known as true meridian or geographical meridian. True meridian at a point is constant. True bearing : The angle between the true meridian and a survey line is known as true bearing or Azimuth of the line. (b) Magnetic meridian and Bearing. Magnetic meridian : Magnetic meridian at a point is the direction indicated by freely suspended, properly balanced and unaffected magnetic needle at that point. Magnetic Bearing : The angle between the magnetic meridian and a survey line is known as magnetic bearing or bearing of the line. It changes with time.
4.What do you understand by Whole circle bearing and quardantal bearing of a line ? Magnetic Bearings are designated by Whole circle bearing system and quadrantal bearing system.
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www.studentskey.in In whole circle bearing system (WCB), the bearing of the line is measured with magnetic north in clockwise direction. It varies from 00 to 3600. In Quadrantal bearing system (O.B or R.B) the bearing of the line is measured eastward or westward from north or south, whichever is nearer. The directions can be either clockwise or anticlockwise. It varies from 00 to 900.
5. Convert the whole circle bearing into reduced bearing: 50o, 176o, 210o, 232o, 150o, 760, 310o, 2420.
6. Differentiate between Prismatic com and Surveyor’s com with reference to reading and tripod Sl.No. 1.
Prismatic (i) The reading is taken with a u help of prism provided at the eye slit (ii) Sighting and reading taking can be done simultaneously from one position of the observer
2.
Tripod may or may not be pivoted
rveyor’s com S
(i) The reading is taken by directly seeing through the top of glass. (ii) Sighting and reading cannot be done from one position of the observer. The instrument cannot be used without a tripod.
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7. The fore bearing of a line PQ is N 280 W. What is its back bearing? In quadrantal bearing (RB) system, the FB and BB are numerically equal but the quadrants are just opposite. The FB of a line PQ is N 280 W, Then its BB is S 280 E.
8. Define : Fore and Back bearing The bearing of a line is measured in the direction of the progress of the survey is called the fore bearing of the (FB) line. The bearing of a line is measured in the direction opposite to the survey is called the back bearing of the (BB) line.
BB=FB + 1800
(FB greater than 1800, use – sign) (FB smaller than 1800, use + sign)
9. The fore bearing of line AB is 155025’25". Identify the back bearing of the line AB in quadrantal system.
The fore bearing of line AB = 155025’20".
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The back bearing of line AB, BB
= FB+1800 =155025’20"+1800 = 335025'20"(WCB) =N(3600-335025’20")W =N240 34' 40" W
10. Define and distinguish between magnetic dip and magnetic declination.
Magnetic dip: Due to the magnetic influence of the earth, the needle does not remain in the balanced position. This inclination of the needle with the horizontal is known as the dip of the magnetic needle. To balance the dip of the needle, a rider (brass of silver coil) is provided along with it.
Magnetic declination: The magnetic meridian of a place is variable one due to some local attractive forces. Therefore, the true meridian and the magnetic meridian at the place do not coincide. The horizontal angle between the magnetic meridian and the true meridian is known as magnetic declination.
11. The magnetic bearing of a line is 480 24’. Calculate the true bearing if the magnetic declinations are 5038’ East and 5038’ west. True bearing = Magnetic bearing + Eastern magnetic declination = 48024’ + 5’38’ True bearing = Magnetic bearing – Western magnetic declination = 48024’-5038 = 42046’. 12. The magnetic bearing of a line is S 28030’E. Calculate the true bearing if the magnetic declination are 5038’ East and 5038’ West. Convert the reduced bearing into Whole circle bearing Magnetic bearing = S 28030’E. (RB) =1800-28030’ =1510300. True bearing = Magnetic bearing + Eastern magnetic declination =151030’+7030’
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www.studentskey.in =159000’. (WCB) =S(1800-159000’)E (RB) =S210E. True bearing = Magnetic bearing – Western magnetic declination =151030’ – 7030’ =144000’ (WCB) =S(1800-144000’)E (RB) =S360E
13. What is local attraction? What are the sources of local attractions? Local attractions is a term used to denote any influence, such as magnetic substances, which prevents the needle from pointing to the magnetic north in a given locality. The source of local attractions are: magnetite in the ground, wire carrying electric current, steel structures, rails, underground iron pipes, chain etc.
14. Distinguish between closed traverse and open traverse.
Sl.No.
Closed traverse
Open traverse
1.
When the lines from a circuit, which ends at the starting point, it is known
If the circuit ends elsewhere, it is known as open traverse.
2.
It is suitable for locating the boundaries of lakes, woods etc.
It is suitable for surveying a long narrow strip of land required for road canal etc.
3.
Check Sum of interior angles =(2n-4)90 Sum of exterior angles = (2n+4)90 Where, n =number of sides of the traverse.
No direct check on angular measurements.
15. What is plane table surveying? When is it preferred? Write its principle. Plane tabling is the graphical method of surveying is which the field observations and plotting proceed simultaneously.
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www.studentskey.in It is mainly suitable for filling the interior details between the control station and also in magnetic areas. The main principle of plane table surveying is that the lines ing the points on the plane table are made to lie parallel to the corresponding lines ing the points on the ground while working at each station.
16. Name four methods of plane surveying. 1. 2. 3. 4.
Radiation Intersection Traversing Resection (i) Resection after orientation by com. (ii) Resection after orientation by back sighting (iii) Researching after orientation by three point problem. a. Mechanical method (Tracing paper method) b. Graphical method (Bessel’s method) c. Lehman’s method (Trial and error method) (iv) Resection after orientation by two point problem.
17. When a three –point problem resorted to in plane table surveying? It is the method of orientation when the table occupies a position not yet located on the drawing sheet. This method is employed when during surveying the surveyor feels that some important details can be plotted easily by choosing any stations. 18. State the First and second Lehman’s rule. First rule: The distance of the point “p” (position of the plane table on the drawing sheet) to be fixed from each rays As (paper a, to ground A), Bb (paper b to ground B) and Cc (paper c, to ground C) is proportional to the respective distant of the stations A, B and C from the ground station P. Second rule: While looking towards the stations the point “p” to be fixed, will be either to the left or to the right of each of the rays.
19. What are the Advantages of plane table surveying? 1. It is useful in magnetic areas. 2. It is cheaper than the theodolite surveying. 3. It is most suitable for small –scale maps. 4. The surveyor can compare plotted work with the actual features.
20. Name some of the errors in plane tabling. 1. 2. 3.
Instrumental error Errors of plotting. Errors due to manipulation and sighting.
1. 2. 3. 4.
Non horizontality of the board. Defective sighting. Defective orientation. Movement of board between sight.
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UNIT III LEVELLING AND APPLICATION 1. Define Levelling. What are the uses of leveling? Levelling is a branch of surveying, the object of which is; (i) To find the elevations of given points with respect to a given or assumed datum, and (ii) To establish points at a given elevation or at different elevations with respect to a given or assumed datum.
2. Define benchmark and reduced level. Benchmark: Benchmark is a relatively permanent point of reference whose elevation with respect to some assumed datum is known.
Reduced level of Elevation: The vertical distance of a point above or below the datum is known as the elevation or R.L. of the point. R.L. of a point may be positive or negative according as the point is above or below datum.
3. What are the different kinds of bench marks? A BM is the reference point of known elevation. It may classified into following types. (i) G.T.S. Bench Mark : The great trigonometrical survey (G.T.S) bench marks are established by the survey of India throughout the country. The levels of this bench marks are established very accurately at a large interval with respect to the mean sea level at Bombay port. (ii) Permanent Bench Mark : These are established by different Government departments like PWD, Railways, Irrigation etc., The RL of these points are determined with reference to the G.T.S. Bench Marks. Points on rocks, culvert, gate pillars, etc. (iii) Temporary bench Mark: These are established temporarily whenever required. These are generally chosen to the day’s work and the start the next days. Points on roofs, walls, basements etc. (iv) Arbitrary Bench mark : When the RL of some fixed points are assumend, they are termed arbitrary benchmark.
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4.What do you mean by datum surface? It is any surface, to which ele4vations are taken as a reference for the determination of elevations of various points. In India the datum adopted for the great trigonometrical survey (G.T.S) is the mean sea level at Bombay port.
5. What is mean by line of collimation and height of collimation? Line of collimation (Line of sight) : It is an imaginary line ing through the intersection of the cross hairs at the diaphragm and the optical centre of the object glass and its continuation. Height of collimation (HOC): The elevation of the Line of collimation (Line of sight) is known as Height of collimation. HOC = RL of BM + BS.
6. Write the different types of levels. 1. 2. 3. 4. 5. 6. 7.
Dumpy level Tilting level Quick setting level. Y-level Reversible level. Automatic level. Lazer level.
7. List the essential parts of a Level Telescope, Eyepiece, Objective Focusing screws. Longitudinal bubble Foot screws, Upper parallel plate (Tribrach), Foot plate (Trivet). Diaphragm adjusting screws, Bubble adjusting screws, Tripod.
8.
What are the different type’s leveling staffs? 1. Target Staff 2. Self reading Staff. a. Solid Staff b. Folding Staff c. Telescopic Staff.
9. Define and distinguish between ‘Back sight’ and “Fore sight” in the process of fly Levelling. Sl.No. 1.
2.
Back sights (BS)
This is the first staff reading taken in any setup of the instrument. It is always taken on a point of known elevation (BM) It is used to determine the height of the instrument. HI = known RL+BS
Fore sight (FS) This is the last staff reading taken in any setup of the instrument, after that instrument is shifted.
It is used to determine the Elevation (RL) of the staff Station. RL = HI-FS
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www.studentskey.in 10. Explain the theory of direct leveling. It is the branch of leveling in which the vertical distances with respect to a horizontal line may be used to determine the relative difference in elevation between two adjacent points. Steps involved: HI=known RL (BM)+BS RL=HI –FS
11. Sl.No.
Distinguish between differential leveling and reciprocal leveling Differential leveling
Reciprocal
1.
Difference in elevation between two or more points is determined by without any regard to the differential leveling.
Difference in elevation between two points is accurately determined by two sets of reciprocal observation
2.
It is used when: (i) two points are a large distance apart. (ii) The difference in elevation between two points is large (iii) Some obstacles intervenes between the points.
It is used when: (i) The instrument cannot be set Between the two points due to an obstruction such as a valley, river, etc.
12. Reduced level of Bench Mark 50.000m Reading on staff held at A 2.435m Reading on staff held at station point B - 1.650m Find : (a) Height of collimation. (b) Reduced level of station point B. (c) Rise/fall of B with respect to A (a)
Height of collimation = RL of BM A +BS (HOC) = 50.000+2.435 = 52.435m
(b)
Reduced level of station point B. = HOC – FS = 52.435-1.650 = 50.785m Rise / fail of B with respect to A = 2.435-1.65 (Lower staff reading being higher) = 0.785m, = with compare to A, the station point B being 0.785m higher.
(c)
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13.
Compare height of collimation method and rise and fall method
Sl.N . o
Height of collimation method
Rise and fall method
1.
It is more rapid, less tedious and simpler as it involves few calculation
It is more laborious and tedious, involving several calculations.
2.
There is no check on the RL of the intermediate points
There is a check of the RL of the intermediate points.
3.
Errors in intermediate RL’s cannot be detected.
Errors in intermediate RL’s can be Detected.
4.
There are two arithemetic checks on the accuracy of RL calculation BS – FS = Last RL – First RL.
There are three arithemetic checks on the accuracy of RL calculation. BS – FS = Rise – Fall = Last RL – First RL.
5.
It is suitable in the case of L.S. and C.S., Contour etc.
It is suitable in fly leveling where I intermediate sights are less.
14. Write the formula for curvature correction, refraction correction and combined correction. Curvature correction Cc=0.07849d2 (negative)m Refraction correction = Cr = 0.01121 d2 (positive)m Combined correction C = Cc – Cr = 0.06728 d2 (negative)m. Note : ‘d’ is to be substituted in Km, while the corrections will be in m.
15.
List out the various sources of errors in leveling. Three principal sources: (i)
(iii)
Instrumental error a. Error due to imperfect adjustment b. Error due to sluggish bubble. c. Error due to movement of objective slide. d. Error due to defective t. e. Error due to incorrect length of staff. (ii) Natural error a. Earth’s curvature b. Atmospheric refraction c. Variations in temperature d. Settlement of tripod e. Wind vibrations. Personal errors a. Mistakes in manipulation. b. Mistake in staff handling. c. Mistake in reading the staff d. Error’s in sighting.
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List out the leveling problems. 1. Levelling on Steep Stop. 2. Levelling on Summits and Hollos. 3. Taking Level of an Overhead Point. 4. Levelling Ponds and Lakes too Wide to be Sighted across. 5. Levelling across River. 6. Levelling on Past High Wall.
17.
Define sensitivity of a bubble. State any two factors affecting the same.
The sensitiveness of a bubble is defined the angular value of one division of the bubble tube. It means the capability of showing small angular movements of the tube vertically. It can be increased by: 1. Increasing the internal radius of the tube. 2. Increasing the diameter of the tube. 3. Increasing the length of the tube. 4. Decreasing the roughness of the walls. 5. Decreasing the viscosity of the liquid.
18. What is a spire test? It is used to make the horizontal axis perpendicular to the vertical axis. This test is also known as the test for the adjustments of the standards. It is done by means of the adjustments of the vertical hair. It is one of the permanent adjustment of the level and theodolite.
19.Define Contour, contour interval and horizontal equivalent. Contour : A contour is an imaginary line on the ground ing the points of equal elevation. Contour interval : It is the vertical distance between any two consecutive contours. It depends upon the nature of the ground, the scale of the map and the purpose of the survey. Horizontal equivalent : It is the horizontal distance between any two consecutive contours. It varies according to the steepness of the ground.
20.
What are the different Characteristics of contour?
1.Contour lines are closed curves. They may either within the map itself or outside the map depending upon the topography.
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www.studentskey.in 21.Sketch the contours for a (a) hillock (b) lake (c) A ridge line (d) A valley line.
22.
What are the uses of contours? 1. Volume of earthwork for any work can be estimate. 2. The capacity of the reservoir or the area of the catchments can be calculated. 3. Very useful in military operations to decide the position of the guns, the line of
march. 4.Longitudinal and cross section can be drawn along any direction to know the nature of the ground.
23.Write the different formulae to calculate the area of the irregular plate. 1. By computations based directly on the field measurements: (i)
By dividing the area into number of triangles.
(ii)
By offsets to base line. a. Mid ordinate rule = O.d b. Average ordinate Rule= nd O n+1 c. Trapezoidal rule = (Oo+On + O1+O2+O3+…..On-1)d d. Simpson’s rule =[(Oo+On)+4(O1+O3+On-1) 2(O2+O4+On-2)] d/3 Oo=Ordinate at one end. On = Ordinate at other end. O1+O2+O3 + ……On-1= Ordinate at end of each division. D=Length of the base.
(iii)
By latitudes and Departures: a. By double meridian distance (D.M.D. method) b. By double parallel distance (D.P.D. method) c. By co-ordinates.
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www.studentskey.in 24. How do you calculate the capacity of the reservoir from the contour map? From the contour map, the capacity of the reservior is calculated by the following formula. 1. Trapezoidal rule = (Ao+An + A1+A2+A3+ …….. An-1)d. 2 2. Primsoidal rule = [(ao+An) + 4 (A1+A3+….An-1) + 2(A2+A4+ …..An-2)] d/3 Ao, A1, A2, A3, ………An = Areas enclosed by successive contours. d=contour interval.
UNIT IV THEODOLITE SURVEYING 1.Define: Theodolite surveying. What are the uses of a theodolite? Theodilite surveying is a branch of surveying, in which the theodolite is accurate instrument used for the measurement of horizontal angles, vertical angels. It can also be used for various purpose such as laying off horizontal angles, locating points on a line, proloning survey lines, establishing grades, determining differences in elevation, etc.
2. Why a type of theodolite is called a transit theodolite? A transit theodolite is one is which the line of sight can be reversed by revolving the telescope through 180 in the vertical plane.
3. List the essential parts of a theodolite. The telescope, the vertical circle, The index frame (T-frame), The leveling head, The scale plate (Lower), The Vernier plate (Upper). The tripod, Plumb bob, The com, Focusing screws, The upper and lower clamp and its tangential screws, Vertical clamp screw, Foot screws etc.,
4. Differentiate between the Vernier theodolite and Micrometer theodolite. In Vernier theodolite the verniers are fitted to read the angles up to 20"
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www.studentskey.in In Micrometer theodolite micrometers are fitted to read the angels.
5. List the essential qualities of a theodolite telescope. The essential parts of the telescope: (i) Objective (ii) Eye-piece, (iii) Diaphragm, (iv) Body and focusing device. The essential qualities of a theodolite telescope: (i) The real image must be formed in front of the eye-piece. (ii) The plane of the image must coincide with that of the cross-hairs.
6.
What are the temporary adjustments of the theodolite? 1.Setting up. 2.Levelling up. 3.Elimination of parallax. (i) Focusing the eye piece. (ii) Focusing the Objective.
7. 1. 2. 3.
List out the permanent adjustments of Theodolite. Adjustment of plate level (Plate level test) Adjustment of line of sight (Cross-hair test) Adjustment of horizontal axis (Spire test) 4. Adjustment of vertical index frame and altitude bubble. (Vertical are test)
8. List out the fundamental lines of Theodolite. 1. 2. 3. 4. 5.
The vertical axis The horizontal axis or trunnion axis. The line of collimation or line of sight. Axis of plate level. Axis of altitude level.
9. What is an anallatic lens? What is the use of an anallatic lens? It is a special convex lens fitted between the object glass and eye piece, at a fixed distance from the object glass, inside the telescope of a tachemeter. The use of an alallatic lens is to reduce the additive constant © to zero. Tachemetric equation, D = Ks+C. Where, D=horizontal distance between the staff and the instrument station. S=Staff intercept. K=Multiplying constant. C=Additive constant.
10. Name the two methods of measuring horizontal angles using a theolite. When each method is advantageously used? The two methods :
(i) (iii)
Repetition method Reiteration method (Direct method)
The method of repetition is preferred for the measurement of a single angle.
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www.studentskey.in The method of reiteration is preferred in triangulation, where a number of angles may be required at one point by the instrument. The method of repetition appears to be better, it is more time consuming and even many repetitions may yield ordinary results.
11.
State what errors are eliminated by repetition method.
1. Errors due to imperfect eccentricity of verniers and centers are eliminated by reading both verniers and taking the mean of the reading. 2. Errors due to imperfect adjustment of the instrument are eliminated by taking face left and right observations. 3. Errors due inaccurate graduation on the main scale are eliminated as the reading are readings are spread over different parts of the circle. 4. Errors due to inaccurate bisection of the signal are eliminated, as they tend to balance each other. All the errors are also minimized as the number of repetitions divides the sum.
12. What are the methods used to plot the traverse? 1. By parallel Meridians Through Each Station. 2. By Included Angles. 3. By paper protractor. 4. By rectangular co-ordinates. 5. Plotting by tangents chords.
13. Define closing error. If a closed traverse is plotted according to the field measurements, the end point of the traverse will not coincide exactly with the starting point, due to the errors in the filed observation. Such as error is known as closing error. Closing error e _ Where,
(L)2 + (D)2
L = sum of latitudes D = sum of departures. The direction of closing error. Tan = D / L
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14. Define : Balancing. What are the methods used to balancing the traverse? The term balancing is generally applied to the operation of applying corrections to latitudes and departures. So that L = sum of latitudes = 0;D = sum of departures=0. This applied only for closed traverse. Methods used to balanceing (adjusting) the traverse: 1. Bowditch’s rule 2. Transit rule 3. Graphical method 4. Axis method
15.Explain the Bowditch’s rule in balancing the traverse. The Bowditch’s rule (com rule) is used to balance a traverse where the linear and angular measurements are the equal precision. In this method the error in linear measurements are proportional to 1 and the error in angular measurements are inversely proportional to 1, where 1 is the length of the line. Correction to latitude (or departure) of any side =Total error in latitude (or departure) x Length of that side Perimeter of traverse CL = L (I/ I ) CD = D (I/I)
Where,
L D L I
= Total error in Latitude = Total error in Departure = Length of the side =Perimeter of traverse
16. What is Gale’s table? What is its use? Traverse computations are usually done a tabular form. One such form is known as Gale’s Table. It is used to balance the traverse and also used to find the area of the closed traverse. Define: Omitted measurement Sometimes it is not possible to take all the measurements due to obstacles. Missing quantities are known as omitted measurements. They can be calculated from the known latitudes and departure.
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17. What is closed traverse? What are the two checks applicable in this case? When the lines from a circuit, which ends at the starting point, it is known as closed traverse. Check: (i) Sum of interior angles =(2n-4) 90 (ii) Sum of exterior angles = (2n+4)90 Where, n=number of side of the traverse.
18. Define : Trigonometrical leveling of Heights and Distances. Trigonometrical leveling is an indirect method of leveling. The relative elevations of various points are determined from the observed vertical angles and horizontal distances by the use of trigonometrical relations. The vertical angles are measured with a theodolite and the horizontal distances are measured with a tape or chain. This method is also known as Heights and Distances.
19. What are the methods used to find the elevations of the points in the case of inaccessible points? 1. Single plane method 2. Double plane method
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UNIT V ENGINEERING SURVEYS 1. Why curves are necessary in the alignment of a highway/ railway? List the various types of curves. During the survey of the alignment of a road, railway, canals, etc. the direction of the line may change due to some unavoidable situations. When two straights of highway or rail way are at some angle to each other, a curve is introduced between them to avoid an abrubt change in direction and to make the vehicle move safely, smoothly and comfortably. Types of curves. 1. Horizontal curve – provided in the horizontal plane. a. Simple curve b. Compound curve c. Reverse curve d. Transition curve. 2.Vertical curve – provided where two straight lines of different gradient interest in the vertical plane. a. Summit curve b. Sag curve
2. What are the three classes of circular curves? a. Simple curve- consists of single are connecting two straights. b. Compound curve – consists of two arcs of different radii bending in same direction. Centres being on the same side if the curve. c.
Reverse curve – consists of two arcs of different radii or equal bending in opposite direction. Centres being on opposite side of the curve.
3. Define degree of curve according to highway practice. The degree of a curve can be defined based on either an arc or a chord. According to the definition, the degree of a curve is the central angle subtended by an are of 30 or 20m length. In highways this are definition is utilized. According to the chord definition, the degree of a curve is the central angle subtended by an are of 30 or 20 m length. In railways this chord definition is utilized.
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www.studentskey.in 4. State the relationship between the radius of a curve and the degree of the curve. If the chord length is 30m, R=1719/D If the chord length is 20m, R=1146/D Where, R = Radius of a curve D = Degree of the curve
5. What are the elements of a simple Circular curve?
1. Back tangent 2. Forward tangent 3. Point of curve (P.C)-T1 4. Point of tangency (P.T)-T2. Point of intersection (P.I)B 6. Intersection angle (I). 7. Deflection angle or Central angel 8. Tangent length (T1B) –t 9. External distance or Apex distant (BD)-e. 12. Mid ordinate (DE) –Oo.
6. Define : Setting out of curves (Curve ranging). What are the methods used for setting curves? Setting out of curves means the location of various points along the curve and ing the same to obtain the actual curves.
The methods used for setting curves: 1. Linear methods (i) Offsets from long chord. (ii) Radial offsets from tangents. (iii) Perpendicular offsets from tangents (iv) Successive bisection of ares. (v) Offsets from the chord produced. 2. Angular methods (i) Rankine’s method of deflection angle (One theodolite method) (ii) Two-thedolite method. (iii) Tacheometric method.
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www.studentskey.in 7. What is Sight distance in highways? Which factors affect if? Sight distance may be defined as the minimum distance two vehicle moving along a curve, when the driver of one vehicle can just see the other vehicles ahead on the road. The factors affecting the sight distance are (i) Height of the line of the sight of the driver (ii) Grade or longitudinal slope of the curve (iii) Speed of the vehicle (iv) Co efficient of friction (v) Efficiency of the break.
8. What is meant by stopping sight distance? It is the minimum distance necessary for the safe movement of traffic within which the driver of a vehicle moving at design speed. After reaching to the presence of a hazard ahead, can bring it to a stop before reaching a hazard. It depends upon (i) (ii) (iii) (iv)
Grade or longitudinal slope of the curve. Speed of the vehicle Co efficient of friction Efficiency of the break
9. Define transition curve: A curve of varying radius known as transition curve or spiral or easement curve. A transition curve is a non circular are introduced on either sides of a circular curve or between the two branches of compound or a reverse curve. It is not provided in highways but is provided in railways.
10. What are the functions of a transition curve? 1. 2. 3. 4.
The radius of the curvature increases or decreases gradually. It is provided for the gradual change in super elevation. It always a gradual transition of curvature from the tangent to the circular curve of from the circular curve to the tangent. It climinates the danger of derailment, overturning or side slipping of vehicles and discomfort to engers.
11. What are the types of transition curve? 1. 2. 3.
Cubic spiral or clothoid or Euler spiral – provided in Railways. Bernoulli’s Lemniscate – provided in Highways. Cubic parabola or Foude’s curve – provided in Railways.
12. What are the aims when undertaking setting out operation? 1.
2.
The structure to be constructed must be set out correctly in all three dimension – both relatively and absolutely, so that it is correct size, in the correct plan position and a correct level. The setting out process, once begun, must proceed quickly, without causing any delay in construction program.
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16 Mark Questions 1. Describe the different kinds of chains used for linear measurements. 2. Explain the two common systems of bearings. 3. What are the sources of errors in com survey? 4. Explain the different operations involved in working with plane table. 5. Explain the radiation and intersection methods of plane tabling. 6. What are the characteristics of contours? 7. Explain the temporary adjustments for a dumpy level. 8. Explain the special methods of spirit leveling 9. Briefly explain the different methods of adjusting a traverse 10. With a neat sketch show the different parts of a simple circular curve 11. What is meant by 3-4-5 rule? How this is applied to a single roomed building? 12. Explain the two basic principles of surveying. 13. Explain with neat sketches the various methods to chain across the river. 14. State the merits and demerits of plane table surveying. 15. With neat sketches explain in detail about Lehman’s rules. 16. Describe the process of repletion and reiteration in horizontal angle measurement. 17. Explain with neat sketches the different types of horizontal curves. 18. What is a vertical curve and why it is provided? Also, show with neat sketches different types of vertical curves. 19. Describe the different types of corrections applied in linear measurement using a tape. 20. Explain with neat sketches any two instruments for setting out right angles to a chain line. 21. What is a planimeter? Explain how the volume of a reservoir could be determined through contour surveying. 22. Explain any two linear methods of setting out circular curves. 23. Tabulate the differences between a prismatic com and a surveyor’s com. 24. Write a detailed note on ‘Gale’s Traverse Table’ 25. With a neat sketch explain the various parts of a prismatic com. Explain how the graduations are marked and why. 26. Explain the different steps in chain surveying. 27. What are the different methods of locating contour? 28. Explain the procedure for setting out of a tunnel. 29. What is two-point problem? Explain how it is solved. 30. Discuss in brief the surveys carried out at various stages of a new highway project and the purpose of each one of them. 31. What are the different instruments used in chain surveying? Explain the use of each with neat sketches. 32. Draw a neat sketch of a modern tilting level and mark it salient parts.
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Department of Civil Engineering Surveying-I (2 marks and 16 marks question and answers)
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UNIT I 1.
INTRODUCTION AND CHAIN SURVEYING Define Surveying. What are the fundamental principals 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 principals of surveying are: (i) Working from whole to part. (ii) To locate a new station by at least two measurements (angular, linear) from fixed reference points.
2.
What is the object or purpose of surveying?
The primary object of surveying is to prepare a plan or map to show the relative position of the objects on the surface of the earth. It is also used to determine the areas, volumes and other related quantities.
3.
Name the different ways of classification of surveys. a. Primary classification (i) (ii)
Plane surveying Geodetic surveying
b. Secondary classification (i) (ii) (iii) (iv)
4.
Based on instruments used Based on methods Based on object Based on nature of the field
Differentiate between plane and geodetic surveying.
Sl.No . 1.
Plane surveying
Geodetic surveying
The curvature of the earth is neglected.
The curvature of the earth is taken.
2.
A line ing any two points is considered straight.
A line ing any two points is considered as curved line.
3.
The triangle formed by any three points is considered as plane triangle.
The triangle formed by any three points is considered as spherical triangle.
4.
It is done on a area less than 250 Km2
It is done on a area greater than 250 Km2
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5.
Classify surveying based on the equipments. 1. Chain surveying 2. Com surveying 3. Plane table surveying 4. Theodolite surveying 5. Tachometric surveying 6. Photogram metric surveying 7. Aerial surveying
6.
Explain the constructions of a diagonal scale.
For a given short length (PQ=PR), draw a right angle triangle. Its base (PR) and height (PQ) are equal. A short length is divided into a number of parts by using the principle of similar triangles in which like sides are proportional. Thus, 1-1 represents 1/10 PQ 9-9 represents 9/10 PQ
7. Define chain surveying. What is the fundamental principle of chain surveying? Chain surveying is the type of surveying in which only linear measurements are made in the field. The main principle of chain surveying or chain triangulation is to provide a framework consist of number of well-conditioned triangles or nearly equilateral triangles. It is used to find the area of the field.
8.
What is well-conditioned triangle? What are its specific advantages?
A triangle is said to be well-conditioned or well proportioned when it contains no angle smaller than 300 and no angle greater then 1200. The main principle of chain surveying is chain triangulation. It consists of frame work of triangles. To plot the network of triangles accurately, the triangles must be
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nearly equal to equilateral or well-conditioned. The distortion due to errors in measurement and plotting should be minimum.
9.
What are the operations involved in chain survey? a. (i) Ranging :The process of locating intermediate points on a straight line between two end points in a straight line. b. (ii) Chaining :The process of measuring the distance with a chain or tape. c. (iii) Offsetting : The process of measuring the lateral distance of the object from the survey line to the left or right according to their positions.
10. What are the instruments required for a chain survey? Chain or tape, Arrows, Pegs, Ranging rods, Offset rods, Laths or whites, Plumb bob, Cross staff and Mallet.
11. Write the different types of Chain. (i) Metric chain (ii) Non-Metric chain
(a) (b) (c) (d)
Gunter's chain or Surveyor's chain Engineer's chain Revenue chain Steel band.
12. Differentiate between Gunter's chain and Engineer's Chain Sl.No. 1.
2.
Gunter's chain or Surveyor's chain It is 66 feet long and divided in to 100 links. 1 link = 0.66 feet Measurements are in miles and furlongs .
Engineer's Chain It is 66 feet long and divided in to 100 links. 1 link = 1 feet. Measurements are in feet and decimals.
13. Define : (a) Main stations. Main station is a prominent point on the chain line and can be either at the beginning of the chain line or at the end or along the boundary. (b) Subsidiary stations : The stations located on the main survey lines are known as Subsidiary stations. (c) Tie stations : These are also subsidiary stations taken on the main survey lines to locate the details of the object.
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www.studentskey.in 14. Draw a neat sketch to show : Base line, Check line, Tie line, offset.
1.
Base line.
2. Check line, 3. Tie line.
4. offset.
15. Distinguish between a check line and a tie line.
16. What are the instruments used for setting out right angles to a chain line ? (i)
Cross staff. a. Open cross staff b. French cross staff c. Adjustable cross staff
(ii) Optical square. (iii) Prism square (iv) Site square.
17. What are offsets ? Classify them. An offset is the lateral distance of an object or ground feature measured from a survey line. The two types of offsets are.
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(i)
Perpendicular offset : The angle of offset from a point on a chain line is
(ii)
Oblique offset : When the angle of offset is other than 900.
900.
Perpendicular offset
Oblique offset
18. What is the use of a line Ranger ? The line Ranger is a small reflecting instrument used for fixing intermediate points on the chain lines. Without going to either end, we can fix the intermediate points.
19. What are the stages of fieldwork in chain surveying ? Or What are the steps involved in chain survey ? 1. Reconnaissance : It is the preliminary inspection of the area to be surveyed. 2. Marking and fixing Survey lines. 3. Running Survey lines. 4. Taking Offsets.
20. Sketch the conventional signs to represent the following : Wall with gate, Railway single line, pond, wire fencing. Object Wall with gate Railway single line Pond Wire fencing
Conventional signs
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www.studentskey.in 21. What are the different tape corrections ? 1. 2. 3. 4. 5.
Correction for absolute length or standardization. Correction for temperature. Correction for pull or tension. Correction for sag. (-ve) Correction for slope. (-ve)
22. What are the errors in chaining ? (i) Compensating Errors : Which are liable to occur in either direction and tend to compensate. (ii) Cumulative Errors : Which occur in the same direction and tend to add or subtract. It may be positive (measured lengths more than the actual length) or negative (measured lengths less than the actual length)
23. What are the different sources of errors in chain surveying ? (i)
Instrumental errors : incorrect length of the chain (Cumulative Errors).
(ii)
Personal error : Bad ranging (Cumulative Errors). Careless holding (Compensating Errors). Non-horizontality (Cumulative Errors). Sag in chain (Cumulative Errors). Miscounting and misreading and booking.
(iii) Natural Errors : Variation in temperature. (Cumulative Errors).
24. Enumerate the instruments used for measurement of lengths of survey lines. (i) (ii) (iii) (iv)
Chain or tape. ometer. Pedometer Odometer Speedometer.
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UNIT II COM SURVEYING AND PLANE TABLE SURVEYING 1.
Define :Com surveying. What are the objects of com surveying ?
Com surveying is the type of surveying in which the direction of the survey lines are measured with a com and the length of the survey lines are measured with a tape or chain in the field.
2.
Write the means of the instruments used in chain surveying. (i)
(ii)
3.
Instruments for the direct measurement of directions : 1. Surveyor's com. 2. Prismatic com. Instruments for the measurement of angles : 1. Sextant. 2. Theodolite
Define : (a).
True meridian, magnetic and bearing.
True meridian : The line or plane ing through the geographical North Pole, South Pole and any point on the surface of the earth, is known as true meridian or geographical meridian. True meridian at a point is constant. True bearing : The angle between the true meridian and a survey line is known as true bearing or Azimuth of the line. (b) Magnetic meridian and Bearing. Magnetic meridian : Magnetic meridian at a point is the direction indicated by freely suspended, properly balanced and unaffected magnetic needle at that point. Magnetic Bearing : The angle between the magnetic meridian and a survey line is known as magnetic bearing or bearing of the line. It changes with time.
4.What do you understand by Whole circle bearing and quardantal bearing of a line ? Magnetic Bearings are designated by Whole circle bearing system and quadrantal bearing system.
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www.studentskey.in In whole circle bearing system (WCB), the bearing of the line is measured with magnetic north in clockwise direction. It varies from 00 to 3600. In Quadrantal bearing system (O.B or R.B) the bearing of the line is measured eastward or westward from north or south, whichever is nearer. The directions can be either clockwise or anticlockwise. It varies from 00 to 900.
5. Convert the whole circle bearing into reduced bearing: 50o, 176o, 210o, 232o, 150o, 760, 310o, 2420.
6. Differentiate between Prismatic com and Surveyor’s com with reference to reading and tripod Sl.No. 1.
Prismatic (i) The reading is taken with a u help of prism provided at the eye slit (ii) Sighting and reading taking can be done simultaneously from one position of the observer
2.
Tripod may or may not be pivoted
rveyor’s com S
(i) The reading is taken by directly seeing through the top of glass. (ii) Sighting and reading cannot be done from one position of the observer. The instrument cannot be used without a tripod.
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7. The fore bearing of a line PQ is N 280 W. What is its back bearing? In quadrantal bearing (RB) system, the FB and BB are numerically equal but the quadrants are just opposite. The FB of a line PQ is N 280 W, Then its BB is S 280 E.
8. Define : Fore and Back bearing The bearing of a line is measured in the direction of the progress of the survey is called the fore bearing of the (FB) line. The bearing of a line is measured in the direction opposite to the survey is called the back bearing of the (BB) line.
BB=FB + 1800
(FB greater than 1800, use – sign) (FB smaller than 1800, use + sign)
9. The fore bearing of line AB is 155025’25". Identify the back bearing of the line AB in quadrantal system.
The fore bearing of line AB = 155025’20".
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The back bearing of line AB, BB
= FB+1800 =155025’20"+1800 = 335025'20"(WCB) =N(3600-335025’20")W =N240 34' 40" W
10. Define and distinguish between magnetic dip and magnetic declination.
Magnetic dip: Due to the magnetic influence of the earth, the needle does not remain in the balanced position. This inclination of the needle with the horizontal is known as the dip of the magnetic needle. To balance the dip of the needle, a rider (brass of silver coil) is provided along with it.
Magnetic declination: The magnetic meridian of a place is variable one due to some local attractive forces. Therefore, the true meridian and the magnetic meridian at the place do not coincide. The horizontal angle between the magnetic meridian and the true meridian is known as magnetic declination.
11. The magnetic bearing of a line is 480 24’. Calculate the true bearing if the magnetic declinations are 5038’ East and 5038’ west. True bearing = Magnetic bearing + Eastern magnetic declination = 48024’ + 5’38’ True bearing = Magnetic bearing – Western magnetic declination = 48024’-5038 = 42046’. 12. The magnetic bearing of a line is S 28030’E. Calculate the true bearing if the magnetic declination are 5038’ East and 5038’ West. Convert the reduced bearing into Whole circle bearing Magnetic bearing = S 28030’E. (RB) =1800-28030’ =1510300. True bearing = Magnetic bearing + Eastern magnetic declination =151030’+7030’
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www.studentskey.in =159000’. (WCB) =S(1800-159000’)E (RB) =S210E. True bearing = Magnetic bearing – Western magnetic declination =151030’ – 7030’ =144000’ (WCB) =S(1800-144000’)E (RB) =S360E
13. What is local attraction? What are the sources of local attractions? Local attractions is a term used to denote any influence, such as magnetic substances, which prevents the needle from pointing to the magnetic north in a given locality. The source of local attractions are: magnetite in the ground, wire carrying electric current, steel structures, rails, underground iron pipes, chain etc.
14. Distinguish between closed traverse and open traverse.
Sl.No.
Closed traverse
Open traverse
1.
When the lines from a circuit, which ends at the starting point, it is known
If the circuit ends elsewhere, it is known as open traverse.
2.
It is suitable for locating the boundaries of lakes, woods etc.
It is suitable for surveying a long narrow strip of land required for road canal etc.
3.
Check Sum of interior angles =(2n-4)90 Sum of exterior angles = (2n+4)90 Where, n =number of sides of the traverse.
No direct check on angular measurements.
15. What is plane table surveying? When is it preferred? Write its principle. Plane tabling is the graphical method of surveying is which the field observations and plotting proceed simultaneously.
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www.studentskey.in It is mainly suitable for filling the interior details between the control station and also in magnetic areas. The main principle of plane table surveying is that the lines ing the points on the plane table are made to lie parallel to the corresponding lines ing the points on the ground while working at each station.
16. Name four methods of plane surveying. 1. 2. 3. 4.
Radiation Intersection Traversing Resection (i) Resection after orientation by com. (ii) Resection after orientation by back sighting (iii) Researching after orientation by three point problem. a. Mechanical method (Tracing paper method) b. Graphical method (Bessel’s method) c. Lehman’s method (Trial and error method) (iv) Resection after orientation by two point problem.
17. When a three –point problem resorted to in plane table surveying? It is the method of orientation when the table occupies a position not yet located on the drawing sheet. This method is employed when during surveying the surveyor feels that some important details can be plotted easily by choosing any stations. 18. State the First and second Lehman’s rule. First rule: The distance of the point “p” (position of the plane table on the drawing sheet) to be fixed from each rays As (paper a, to ground A), Bb (paper b to ground B) and Cc (paper c, to ground C) is proportional to the respective distant of the stations A, B and C from the ground station P. Second rule: While looking towards the stations the point “p” to be fixed, will be either to the left or to the right of each of the rays.
19. What are the Advantages of plane table surveying? 1. It is useful in magnetic areas. 2. It is cheaper than the theodolite surveying. 3. It is most suitable for small –scale maps. 4. The surveyor can compare plotted work with the actual features.
20. Name some of the errors in plane tabling. 1. 2. 3.
Instrumental error Errors of plotting. Errors due to manipulation and sighting.
1. 2. 3. 4.
Non horizontality of the board. Defective sighting. Defective orientation. Movement of board between sight.
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UNIT III LEVELLING AND APPLICATION 1. Define Levelling. What are the uses of leveling? Levelling is a branch of surveying, the object of which is; (i) To find the elevations of given points with respect to a given or assumed datum, and (ii) To establish points at a given elevation or at different elevations with respect to a given or assumed datum.
2. Define benchmark and reduced level. Benchmark: Benchmark is a relatively permanent point of reference whose elevation with respect to some assumed datum is known.
Reduced level of Elevation: The vertical distance of a point above or below the datum is known as the elevation or R.L. of the point. R.L. of a point may be positive or negative according as the point is above or below datum.
3. What are the different kinds of bench marks? A BM is the reference point of known elevation. It may classified into following types. (i) G.T.S. Bench Mark : The great trigonometrical survey (G.T.S) bench marks are established by the survey of India throughout the country. The levels of this bench marks are established very accurately at a large interval with respect to the mean sea level at Bombay port. (ii) Permanent Bench Mark : These are established by different Government departments like PWD, Railways, Irrigation etc., The RL of these points are determined with reference to the G.T.S. Bench Marks. Points on rocks, culvert, gate pillars, etc. (iii) Temporary bench Mark: These are established temporarily whenever required. These are generally chosen to the day’s work and the start the next days. Points on roofs, walls, basements etc. (iv) Arbitrary Bench mark : When the RL of some fixed points are assumend, they are termed arbitrary benchmark.
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4.What do you mean by datum surface? It is any surface, to which ele4vations are taken as a reference for the determination of elevations of various points. In India the datum adopted for the great trigonometrical survey (G.T.S) is the mean sea level at Bombay port.
5. What is mean by line of collimation and height of collimation? Line of collimation (Line of sight) : It is an imaginary line ing through the intersection of the cross hairs at the diaphragm and the optical centre of the object glass and its continuation. Height of collimation (HOC): The elevation of the Line of collimation (Line of sight) is known as Height of collimation. HOC = RL of BM + BS.
6. Write the different types of levels. 1. 2. 3. 4. 5. 6. 7.
Dumpy level Tilting level Quick setting level. Y-level Reversible level. Automatic level. Lazer level.
7. List the essential parts of a Level Telescope, Eyepiece, Objective Focusing screws. Longitudinal bubble Foot screws, Upper parallel plate (Tribrach), Foot plate (Trivet). Diaphragm adjusting screws, Bubble adjusting screws, Tripod.
8.
What are the different type’s leveling staffs? 1. Target Staff 2. Self reading Staff. a. Solid Staff b. Folding Staff c. Telescopic Staff.
9. Define and distinguish between ‘Back sight’ and “Fore sight” in the process of fly Levelling. Sl.No. 1.
2.
Back sights (BS)
This is the first staff reading taken in any setup of the instrument. It is always taken on a point of known elevation (BM) It is used to determine the height of the instrument. HI = known RL+BS
Fore sight (FS) This is the last staff reading taken in any setup of the instrument, after that instrument is shifted.
It is used to determine the Elevation (RL) of the staff Station. RL = HI-FS
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www.studentskey.in 10. Explain the theory of direct leveling. It is the branch of leveling in which the vertical distances with respect to a horizontal line may be used to determine the relative difference in elevation between two adjacent points. Steps involved: HI=known RL (BM)+BS RL=HI –FS
11. Sl.No.
Distinguish between differential leveling and reciprocal leveling Differential leveling
Reciprocal
1.
Difference in elevation between two or more points is determined by without any regard to the differential leveling.
Difference in elevation between two points is accurately determined by two sets of reciprocal observation
2.
It is used when: (i) two points are a large distance apart. (ii) The difference in elevation between two points is large (iii) Some obstacles intervenes between the points.
It is used when: (i) The instrument cannot be set Between the two points due to an obstruction such as a valley, river, etc.
12. Reduced level of Bench Mark 50.000m Reading on staff held at A 2.435m Reading on staff held at station point B - 1.650m Find : (a) Height of collimation. (b) Reduced level of station point B. (c) Rise/fall of B with respect to A (a)
Height of collimation = RL of BM A +BS (HOC) = 50.000+2.435 = 52.435m
(b)
Reduced level of station point B. = HOC – FS = 52.435-1.650 = 50.785m Rise / fail of B with respect to A = 2.435-1.65 (Lower staff reading being higher) = 0.785m, = with compare to A, the station point B being 0.785m higher.
(c)
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13.
Compare height of collimation method and rise and fall method
Sl.N . o
Height of collimation method
Rise and fall method
1.
It is more rapid, less tedious and simpler as it involves few calculation
It is more laborious and tedious, involving several calculations.
2.
There is no check on the RL of the intermediate points
There is a check of the RL of the intermediate points.
3.
Errors in intermediate RL’s cannot be detected.
Errors in intermediate RL’s can be Detected.
4.
There are two arithemetic checks on the accuracy of RL calculation BS – FS = Last RL – First RL.
There are three arithemetic checks on the accuracy of RL calculation. BS – FS = Rise – Fall = Last RL – First RL.
5.
It is suitable in the case of L.S. and C.S., Contour etc.
It is suitable in fly leveling where I intermediate sights are less.
14. Write the formula for curvature correction, refraction correction and combined correction. Curvature correction Cc=0.07849d2 (negative)m Refraction correction = Cr = 0.01121 d2 (positive)m Combined correction C = Cc – Cr = 0.06728 d2 (negative)m. Note : ‘d’ is to be substituted in Km, while the corrections will be in m.
15.
List out the various sources of errors in leveling. Three principal sources: (i)
(iii)
Instrumental error a. Error due to imperfect adjustment b. Error due to sluggish bubble. c. Error due to movement of objective slide. d. Error due to defective t. e. Error due to incorrect length of staff. (ii) Natural error a. Earth’s curvature b. Atmospheric refraction c. Variations in temperature d. Settlement of tripod e. Wind vibrations. Personal errors a. Mistakes in manipulation. b. Mistake in staff handling. c. Mistake in reading the staff d. Error’s in sighting.
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List out the leveling problems. 1. Levelling on Steep Stop. 2. Levelling on Summits and Hollos. 3. Taking Level of an Overhead Point. 4. Levelling Ponds and Lakes too Wide to be Sighted across. 5. Levelling across River. 6. Levelling on Past High Wall.
17.
Define sensitivity of a bubble. State any two factors affecting the same.
The sensitiveness of a bubble is defined the angular value of one division of the bubble tube. It means the capability of showing small angular movements of the tube vertically. It can be increased by: 1. Increasing the internal radius of the tube. 2. Increasing the diameter of the tube. 3. Increasing the length of the tube. 4. Decreasing the roughness of the walls. 5. Decreasing the viscosity of the liquid.
18. What is a spire test? It is used to make the horizontal axis perpendicular to the vertical axis. This test is also known as the test for the adjustments of the standards. It is done by means of the adjustments of the vertical hair. It is one of the permanent adjustment of the level and theodolite.
19.Define Contour, contour interval and horizontal equivalent. Contour : A contour is an imaginary line on the ground ing the points of equal elevation. Contour interval : It is the vertical distance between any two consecutive contours. It depends upon the nature of the ground, the scale of the map and the purpose of the survey. Horizontal equivalent : It is the horizontal distance between any two consecutive contours. It varies according to the steepness of the ground.
20.
What are the different Characteristics of contour?
1.Contour lines are closed curves. They may either within the map itself or outside the map depending upon the topography.
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www.studentskey.in 21.Sketch the contours for a (a) hillock (b) lake (c) A ridge line (d) A valley line.
22.
What are the uses of contours? 1. Volume of earthwork for any work can be estimate. 2. The capacity of the reservoir or the area of the catchments can be calculated. 3. Very useful in military operations to decide the position of the guns, the line of
march. 4.Longitudinal and cross section can be drawn along any direction to know the nature of the ground.
23.Write the different formulae to calculate the area of the irregular plate. 1. By computations based directly on the field measurements: (i)
By dividing the area into number of triangles.
(ii)
By offsets to base line. a. Mid ordinate rule = O.d b. Average ordinate Rule= nd O n+1 c. Trapezoidal rule = (Oo+On + O1+O2+O3+…..On-1)d d. Simpson’s rule =[(Oo+On)+4(O1+O3+On-1) 2(O2+O4+On-2)] d/3 Oo=Ordinate at one end. On = Ordinate at other end. O1+O2+O3 + ……On-1= Ordinate at end of each division. D=Length of the base.
(iii)
By latitudes and Departures: a. By double meridian distance (D.M.D. method) b. By double parallel distance (D.P.D. method) c. By co-ordinates.
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www.studentskey.in 24. How do you calculate the capacity of the reservoir from the contour map? From the contour map, the capacity of the reservior is calculated by the following formula. 1. Trapezoidal rule = (Ao+An + A1+A2+A3+ …….. An-1)d. 2 2. Primsoidal rule = [(ao+An) + 4 (A1+A3+….An-1) + 2(A2+A4+ …..An-2)] d/3 Ao, A1, A2, A3, ………An = Areas enclosed by successive contours. d=contour interval.
UNIT IV THEODOLITE SURVEYING 1.Define: Theodolite surveying. What are the uses of a theodolite? Theodilite surveying is a branch of surveying, in which the theodolite is accurate instrument used for the measurement of horizontal angles, vertical angels. It can also be used for various purpose such as laying off horizontal angles, locating points on a line, proloning survey lines, establishing grades, determining differences in elevation, etc.
2. Why a type of theodolite is called a transit theodolite? A transit theodolite is one is which the line of sight can be reversed by revolving the telescope through 180 in the vertical plane.
3. List the essential parts of a theodolite. The telescope, the vertical circle, The index frame (T-frame), The leveling head, The scale plate (Lower), The Vernier plate (Upper). The tripod, Plumb bob, The com, Focusing screws, The upper and lower clamp and its tangential screws, Vertical clamp screw, Foot screws etc.,
4. Differentiate between the Vernier theodolite and Micrometer theodolite. In Vernier theodolite the verniers are fitted to read the angles up to 20"
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www.studentskey.in In Micrometer theodolite micrometers are fitted to read the angels.
5. List the essential qualities of a theodolite telescope. The essential parts of the telescope: (i) Objective (ii) Eye-piece, (iii) Diaphragm, (iv) Body and focusing device. The essential qualities of a theodolite telescope: (i) The real image must be formed in front of the eye-piece. (ii) The plane of the image must coincide with that of the cross-hairs.
6.
What are the temporary adjustments of the theodolite? 1.Setting up. 2.Levelling up. 3.Elimination of parallax. (i) Focusing the eye piece. (ii) Focusing the Objective.
7. 1. 2. 3.
List out the permanent adjustments of Theodolite. Adjustment of plate level (Plate level test) Adjustment of line of sight (Cross-hair test) Adjustment of horizontal axis (Spire test) 4. Adjustment of vertical index frame and altitude bubble. (Vertical are test)
8. List out the fundamental lines of Theodolite. 1. 2. 3. 4. 5.
The vertical axis The horizontal axis or trunnion axis. The line of collimation or line of sight. Axis of plate level. Axis of altitude level.
9. What is an anallatic lens? What is the use of an anallatic lens? It is a special convex lens fitted between the object glass and eye piece, at a fixed distance from the object glass, inside the telescope of a tachemeter. The use of an alallatic lens is to reduce the additive constant © to zero. Tachemetric equation, D = Ks+C. Where, D=horizontal distance between the staff and the instrument station. S=Staff intercept. K=Multiplying constant. C=Additive constant.
10. Name the two methods of measuring horizontal angles using a theolite. When each method is advantageously used? The two methods :
(i) (iii)
Repetition method Reiteration method (Direct method)
The method of repetition is preferred for the measurement of a single angle.
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www.studentskey.in The method of reiteration is preferred in triangulation, where a number of angles may be required at one point by the instrument. The method of repetition appears to be better, it is more time consuming and even many repetitions may yield ordinary results.
11.
State what errors are eliminated by repetition method.
1. Errors due to imperfect eccentricity of verniers and centers are eliminated by reading both verniers and taking the mean of the reading. 2. Errors due to imperfect adjustment of the instrument are eliminated by taking face left and right observations. 3. Errors due inaccurate graduation on the main scale are eliminated as the reading are readings are spread over different parts of the circle. 4. Errors due to inaccurate bisection of the signal are eliminated, as they tend to balance each other. All the errors are also minimized as the number of repetitions divides the sum.
12. What are the methods used to plot the traverse? 1. By parallel Meridians Through Each Station. 2. By Included Angles. 3. By paper protractor. 4. By rectangular co-ordinates. 5. Plotting by tangents chords.
13. Define closing error. If a closed traverse is plotted according to the field measurements, the end point of the traverse will not coincide exactly with the starting point, due to the errors in the filed observation. Such as error is known as closing error. Closing error e _ Where,
(L)2 + (D)2
L = sum of latitudes D = sum of departures. The direction of closing error. Tan = D / L
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14. Define : Balancing. What are the methods used to balancing the traverse? The term balancing is generally applied to the operation of applying corrections to latitudes and departures. So that L = sum of latitudes = 0;D = sum of departures=0. This applied only for closed traverse. Methods used to balanceing (adjusting) the traverse: 1. Bowditch’s rule 2. Transit rule 3. Graphical method 4. Axis method
15.Explain the Bowditch’s rule in balancing the traverse. The Bowditch’s rule (com rule) is used to balance a traverse where the linear and angular measurements are the equal precision. In this method the error in linear measurements are proportional to 1 and the error in angular measurements are inversely proportional to 1, where 1 is the length of the line. Correction to latitude (or departure) of any side =Total error in latitude (or departure) x Length of that side Perimeter of traverse CL = L (I/ I ) CD = D (I/I)
Where,
L D L I
= Total error in Latitude = Total error in Departure = Length of the side =Perimeter of traverse
16. What is Gale’s table? What is its use? Traverse computations are usually done a tabular form. One such form is known as Gale’s Table. It is used to balance the traverse and also used to find the area of the closed traverse. Define: Omitted measurement Sometimes it is not possible to take all the measurements due to obstacles. Missing quantities are known as omitted measurements. They can be calculated from the known latitudes and departure.
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17. What is closed traverse? What are the two checks applicable in this case? When the lines from a circuit, which ends at the starting point, it is known as closed traverse. Check: (i) Sum of interior angles =(2n-4) 90 (ii) Sum of exterior angles = (2n+4)90 Where, n=number of side of the traverse.
18. Define : Trigonometrical leveling of Heights and Distances. Trigonometrical leveling is an indirect method of leveling. The relative elevations of various points are determined from the observed vertical angles and horizontal distances by the use of trigonometrical relations. The vertical angles are measured with a theodolite and the horizontal distances are measured with a tape or chain. This method is also known as Heights and Distances.
19. What are the methods used to find the elevations of the points in the case of inaccessible points? 1. Single plane method 2. Double plane method
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UNIT V ENGINEERING SURVEYS 1. Why curves are necessary in the alignment of a highway/ railway? List the various types of curves. During the survey of the alignment of a road, railway, canals, etc. the direction of the line may change due to some unavoidable situations. When two straights of highway or rail way are at some angle to each other, a curve is introduced between them to avoid an abrubt change in direction and to make the vehicle move safely, smoothly and comfortably. Types of curves. 1. Horizontal curve – provided in the horizontal plane. a. Simple curve b. Compound curve c. Reverse curve d. Transition curve. 2.Vertical curve – provided where two straight lines of different gradient interest in the vertical plane. a. Summit curve b. Sag curve
2. What are the three classes of circular curves? a. Simple curve- consists of single are connecting two straights. b. Compound curve – consists of two arcs of different radii bending in same direction. Centres being on the same side if the curve. c.
Reverse curve – consists of two arcs of different radii or equal bending in opposite direction. Centres being on opposite side of the curve.
3. Define degree of curve according to highway practice. The degree of a curve can be defined based on either an arc or a chord. According to the definition, the degree of a curve is the central angle subtended by an are of 30 or 20m length. In highways this are definition is utilized. According to the chord definition, the degree of a curve is the central angle subtended by an are of 30 or 20 m length. In railways this chord definition is utilized.
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www.studentskey.in 4. State the relationship between the radius of a curve and the degree of the curve. If the chord length is 30m, R=1719/D If the chord length is 20m, R=1146/D Where, R = Radius of a curve D = Degree of the curve
5. What are the elements of a simple Circular curve?
1. Back tangent 2. Forward tangent 3. Point of curve (P.C)-T1 4. Point of tangency (P.T)-T2. Point of intersection (P.I)B 6. Intersection angle (I). 7. Deflection angle or Central angel 8. Tangent length (T1B) –t 9. External distance or Apex distant (BD)-e. 12. Mid ordinate (DE) –Oo.
6. Define : Setting out of curves (Curve ranging). What are the methods used for setting curves? Setting out of curves means the location of various points along the curve and ing the same to obtain the actual curves.
The methods used for setting curves: 1. Linear methods (i) Offsets from long chord. (ii) Radial offsets from tangents. (iii) Perpendicular offsets from tangents (iv) Successive bisection of ares. (v) Offsets from the chord produced. 2. Angular methods (i) Rankine’s method of deflection angle (One theodolite method) (ii) Two-thedolite method. (iii) Tacheometric method.
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www.studentskey.in 7. What is Sight distance in highways? Which factors affect if? Sight distance may be defined as the minimum distance two vehicle moving along a curve, when the driver of one vehicle can just see the other vehicles ahead on the road. The factors affecting the sight distance are (i) Height of the line of the sight of the driver (ii) Grade or longitudinal slope of the curve (iii) Speed of the vehicle (iv) Co efficient of friction (v) Efficiency of the break.
8. What is meant by stopping sight distance? It is the minimum distance necessary for the safe movement of traffic within which the driver of a vehicle moving at design speed. After reaching to the presence of a hazard ahead, can bring it to a stop before reaching a hazard. It depends upon (i) (ii) (iii) (iv)
Grade or longitudinal slope of the curve. Speed of the vehicle Co efficient of friction Efficiency of the break
9. Define transition curve: A curve of varying radius known as transition curve or spiral or easement curve. A transition curve is a non circular are introduced on either sides of a circular curve or between the two branches of compound or a reverse curve. It is not provided in highways but is provided in railways.
10. What are the functions of a transition curve? 1. 2. 3. 4.
The radius of the curvature increases or decreases gradually. It is provided for the gradual change in super elevation. It always a gradual transition of curvature from the tangent to the circular curve of from the circular curve to the tangent. It climinates the danger of derailment, overturning or side slipping of vehicles and discomfort to engers.
11. What are the types of transition curve? 1. 2. 3.
Cubic spiral or clothoid or Euler spiral – provided in Railways. Bernoulli’s Lemniscate – provided in Highways. Cubic parabola or Foude’s curve – provided in Railways.
12. What are the aims when undertaking setting out operation? 1.
2.
The structure to be constructed must be set out correctly in all three dimension – both relatively and absolutely, so that it is correct size, in the correct plan position and a correct level. The setting out process, once begun, must proceed quickly, without causing any delay in construction program.
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16 Mark Questions 1. Describe the different kinds of chains used for linear measurements. 2. Explain the two common systems of bearings. 3. What are the sources of errors in com survey? 4. Explain the different operations involved in working with plane table. 5. Explain the radiation and intersection methods of plane tabling. 6. What are the characteristics of contours? 7. Explain the temporary adjustments for a dumpy level. 8. Explain the special methods of spirit leveling 9. Briefly explain the different methods of adjusting a traverse 10. With a neat sketch show the different parts of a simple circular curve 11. What is meant by 3-4-5 rule? How this is applied to a single roomed building? 12. Explain the two basic principles of surveying. 13. Explain with neat sketches the various methods to chain across the river. 14. State the merits and demerits of plane table surveying. 15. With neat sketches explain in detail about Lehman’s rules. 16. Describe the process of repletion and reiteration in horizontal angle measurement. 17. Explain with neat sketches the different types of horizontal curves. 18. What is a vertical curve and why it is provided? Also, show with neat sketches different types of vertical curves. 19. Describe the different types of corrections applied in linear measurement using a tape. 20. Explain with neat sketches any two instruments for setting out right angles to a chain line. 21. What is a planimeter? Explain how the volume of a reservoir could be determined through contour surveying. 22. Explain any two linear methods of setting out circular curves. 23. Tabulate the differences between a prismatic com and a surveyor’s com. 24. Write a detailed note on ‘Gale’s Traverse Table’ 25. With a neat sketch explain the various parts of a prismatic com. Explain how the graduations are marked and why. 26. Explain the different steps in chain surveying. 27. What are the different methods of locating contour? 28. Explain the procedure for setting out of a tunnel. 29. What is two-point problem? Explain how it is solved. 30. Discuss in brief the surveys carried out at various stages of a new highway project and the purpose of each one of them. 31. What are the different instruments used in chain surveying? Explain the use of each with neat sketches. 32. Draw a neat sketch of a modern tilting level and mark it salient parts.
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