Recent questions tagged surveying

Description : As used in survey

Last Answer : It's the operation of changing the face of telescope from left to right and vice versa.

Description : The process of surveying is therefore in three stages namely:

Last Answer : (i) Taking a general view This part of the definition is important as it indicates the need to obtain an overall picture of what is required before any type of survey work is undertaken. In ... of quantities, datasheets, drawings and in land surveying maps and plan showing the features on the land.

Description : Tacheometric Surveying

Last Answer : Tacheometric is a branch of surveying in which horizontal and vertical distances are determined by taking angular observation with an instrument known as a tachometer. Tacheometric surveying is adopted in rough ... be prepared for investigation works within a short time on the basis of such survey.

Description : Explain the temporary adjustments of prismatic compass.

Last Answer : Temporary Adjustments of Prismatic Compass 1. Fixing the compass to the tripod The compass is fixed on a tripod by rotating screw head of tripod stand. 2. Centering the compass The prismatic compass ... prism is moved using focusing stud so that readings on graduated ring will be seen clearly. 

Description : State the fundamental axes and mention their relationship for a dumpy level.

Last Answer : Fundamental axis of dumpy level are as follows; i) The vertical axis ii) The axis of bubble tube iii) The line of collimation iv) The axis of the telescope Relationship between ... iii) Axis of telescope and line of collimation should coincide when dumpy level is correctly leveled.

Description : Describe with neat sketch, the optical square and explain its principle.

Last Answer : Principal of optical square :- the angle between the first incident ray and the last reflected ray is twice the angle between the two mirrors OR If there are two plane mirrors whose reflecting surfaces ... is 450 while that between the first incident ray and last reflected ray is 900 .  

Description : What consideration would you have while selecting survey stations and survey lines in a chain survey?

Last Answer : Following points to be considered while selecting survey stations and survey lines 1) Main survey station should be mutually visible. 2) All triangles should be well conditioned. 3) The survey line should lie ... of the area so as to form the frame work of triangles on it to cover maximum area. 

Description : What are offsets? How are they taken and recorded? Explain with sketch.

Last Answer : Offsets are lateral measurement to the base line. They are Located by judgment if short And by instruments (optical square or cross staff) if long and measured by metallic tape and shown with their chainages on base line

Description : Define fly leveling and profile leveling

Last Answer : Fly Leveling adopted to transfer bench marks from one place to other .In this leveling only FS & BS are taken.  Profile leveling:- The operation in which the object is to determine the ... known distanced apart along a given line to obtained the accurate outline of the surface of the ground 

Description : Define : 1) Bench mark 2) Datum surface 3) Line of collimation 4) Change Point 

Last Answer : 1) Bench mark: - It is a fixed reference point of known elevation.. 2)Datum surface :-It is any arbitrarily assumed level surface from which vertical distance are measured 3) Line of collimation:- ... which the fore and back sights are taken.  It is the point denoting the shifting of the level.

Description : State the situation where plane table is suitable. 

Last Answer : 1) It is most suitable for preparing small scale maps 2) It is suitable in magnetic are where compass survey is not reliable 3) It is most suitable for filling in details between stations fixed by triangulation 4) It is suitable where accuracy is not required.

Description : How would you detect presence of local attraction at a place ?

Last Answer : The presence of local attraction may be detected by finding difference of FB & BB of the line. If the fore bearing and back bearing difference is 1800 then there is no local attraction at both ... difference is not equal to 1800 then there is local attraction at both or any one station. 

Description : Define: WCB and Quadrantal Bearing system

Last Answer : Ans.: 1)WCB:-In this system the bearing of a line is always measured clockwise for the north point of the reference meridian towards the line round the circle the angle thus measured is called ... the bearing of a line is measured clockwise from the north point or south point whichever is nearest .

Description : State the two uses of survey based on geodetic surveying

Last Answer : Two uses of survey based on geodetic surveying:- i) To determine the precise position s on the surface of the earth. ii) Preparation of maps of large area like map of a country, state ... ) Establishment of GTS bench Marks across the country. iv) Preparation of military maps for defense purposes.

Description : Write errors in leveling and corresponding precaution

Last Answer : i) Instrument error with respect to bubble tube, leveling staff. 1.If bubble tube is sluggish it may apparently be in the center though the bubble line is not horizontal. Precaution - ... reading. Precaution- Leveling should be properly done by bringing the bubble of bubble tube at Centre.

Description : State the important points kept in mind while recording the staff readings in level pages with respect first reading, intermediate reading, last reading, change point, carry forward from one page to next page-Remark

Last Answer : 1) First reading is on bench mark point and should be noted in back sight(BS) column 2) Intermediate reading (IS) should be taken on the points between first and last station. 3) Last reading ... column of next page 6) Remark column should have denote First and Last RL along with change points.

Description : State the purposes of following methods of leveling. i)Profile leveling, ii)Fly leveling, iii)Check leveling iv)Reciprocal leveling

Last Answer : 1. Profile leveling- To determine the undulation of ground surface along given line for alignment of road, canal or pipe, railway line 2. Fly leveling-It is used to for connecting B.M. to ... is used to find the difference in leveling between two points two point obstructed due to river or pond.

Description : Draw a sketch and explain how to find height of chajja or slab using dumpy level.

Last Answer : Explanation : 1. First the back sight reading is taken on floor level whose RL is known to us; from which RL of instrument axis can be find out by adding RL of BM and BS reading. 2. Now ... staff reading. 4. Finally height of chajja is calculated as RL of slab bottom -  RL of floor top.

Description : Explain temporary adjustment.

Last Answer : 1) Place the telescope parallel to foot screw (fig. a) 2) Bring the bubble at Centre by moving foot screw inward or outward simultaneously. 3) Then turn the telescope through 900 so that it ... 6) Once both positions give centered bubble, leveling of instrument is said to be completed.

Description : State fundamental lines and their relationships with each other of dumpy level.

Last Answer : Fundamental axes of dumpy level : i) The vertical axis ii) The axis of bubble tube iii) The line of collimation iv) The axis of the telescope Relations of Fundamental axes : i) The ... to the axis of the bubble tube. iii) Axis of telescope and line of collimation should coincide.

Description : State advantages of plane table survey one each with respect to booking and suitability

Last Answer : Booking of observations: i) Field work and plotting work done simultaneously ii) ) Notes of measurement are seldom required and possibility of mistakes in booking is eliminated. Suitability of PT ... and work where great accuracy is not required. ii) Mostly suitable for survey in plain terrain

Description : State two advantages of telescopic alidade over simple alidade.

Last Answer : Advantages of telescopic alidade : i) Telescopic alidade is more accurate in bisection than simple alidade ii) Telescopic alidade is useful in comparatively longer range objects. iii) It can be easily ... is not possible by simple alidade. iv) It gives quicker bisection which saves time ultimately.

Description : Write any four advantages of intersection method of plane tabling over radiation method of plane tabling.

Last Answer : Advantages of intersection method: 1. Interection method requires less ground distance measurement than radiation method. 2. By this method we can locate inaccessible points which cannot be ... to radiation method, intersection method eliminates undulation error, bisection error and plotting errors.

Description : Draw sketch and explain method of traversing of plane table surveying. 

Last Answer : Procedure: 1.Set plane table over station A use plumbing fork for transferring station point from ground on sheet. Draw the direction of magnetic meridian with the help of compass. 2. With the ... scale Similarly, the table can be set at other successive station and traverse is completed.

Description : Define orientation. State two methods of orientation. Which method is most accurate and why? 

Last Answer : Orientation is the process of keeping plane table in same position as that is occupied in previous station. Methods of orientation: i) Magnetic meridian method using trough compass ii) Back ... and not by using trough compass. Therefore there is no error occurring due to local attraction.

Description : Why zero is marked at south end on a graduated circle of prismatic compass?

Last Answer : As bearing of any line is measured with respective north direction, while observing north direction, reading should be 00 0'. Therefore when object vane is bisecting north direction, at the same ... get bearings with respective north direction always, zero is marked at south end of magnetic needle.

Description : State temporary adjustments of prismatic compass

Last Answer : a) Setting the prismatic compass over prefixed survey station b) Centering the compass over nail point of station using plumb bob c) Leveling of compass in horizontal plane using level tube d) Focusing of prism by raising and lowering the focussing stud

Description : Define the terms i) Fore Bearing, ii) Open traverse, iii) Closing error, iv) Reduced bearing

Last Answer : i) Fore bearing : The bearing observed in the direction of progress of survey in clockwise manner is called fore bearing  ii) Open traverse : When the first and last survey lines does ... north or south direction in clockwise or anticlockwise manner is known as reduced or quadrantal bearing. 

Description : Write the functions of the following components of prismatic compass i) Prism, ii) Lifting pin, iii) Prism cap, iv) Agate cap

Last Answer : i) Prism: Reading printed on horizontal face of compass ring can be read from vertical position  ii) Lifting pin: When the instrument not in use the sight vane passes against the lifting pin which lift ... piece of hard glass provided on top of pivoted point, to reduce wear and tear of the point

Description : Define Dip and deflection of needle.

Last Answer : Dip of the magnetic needle: It is the upward or downward movement of magnetic needle in vertical plane due to earth's gravitational force is known as dip of needle. Deflection of needle : ... west direction, that horizontal angle between magnetic and true north is said to be declination of needle.

Description : Write three types of obstacles in chaining with examples. 

Last Answer : 1. Obstacle which can be chained across but cannot be ranged across. , Examples: Hill Intervening , rising ground. 2. Obstacle which can be ranged but cannot be chained across., Example: ... . 3. Obstacle which can be neither be ranged across not be chained across, Example: Building obstruction

Description : Draw sketch and write the procedure for setting offset to the left or right side of suvey line with open cross-staff.

Last Answer : Procedure for setting offset with open cross staff : 1. Keep the ranging rods at point P(fixed on survey line) and at point A1 approximately. 2. The cross staff with stadia rod is fixed ... can be fixed and perpendicular offset AB is said to be set to given survey line PQ in left side.

Description : State four instruments used for setting offsets.

Last Answer : i) Instruments used for setting offsets: 1)Chain 2)Tape 3) Open & French Cross Staff 4) Circular & Indian Optical Square  ii) Principle of optical square: The angle between the first incident ray and the last reflected ray is twice to that of angle between two mirrors in optical square.

Description : Defines the terms : i) Survey Station ii) Survey Line iii)Offset iv)Triangulation 

Last Answer : i) Survey Station : It is the point on ground from which various observations are taken around it. ii) Survey Line : It is the straight line joining two successive survey stations ... iv)Triangulation : The frame work consist of number of connected well conditional triangle is called Triangulation.

Description : A 20m chain was found to be 6cm too long after chaining a distance of 1059m. It was found to be 9cm too short after chaining at the end 1985m. If the chain was correct before commencement of work find the true distance.

Last Answer : Given : Line ABC, AB=1059m, AC=1985m  L= 20m, No error at start, 0.06m too long at B,  0.09m too short  Find : True distance of AC = ? Solution : For part AB L = Length of chain= 20 m e = Average ... Total true distance of AC = True distance of (AB + BC)  = 1060.59 m + 922.52 m  = 1983.11 m

Description : Write the code of signals used in ranging with respect to : i) Correct position ii) Fix the ranging rod iii) Vertical position of ranging rod iv) Move slowly to left of observer 

Last Answer : i) Correct position : Both hands above Head and then Brought Down ii) Fix the ranging rod : Both Arms extended forward horizontally and the hands depressed briskly iii) Vertical position of ranging rod : 1 ... and moved to the Left iv) Move slowly to left of observer : Slow sweeps with Left Hand

Description : Explain in brief linear measurement using : i) Pacing ii) Digital Tape 

Last Answer : i) Pacing : This method is used only for knowing approximate distance between the objects. In preliminary survey this method can be used for linear measurement. This method consists of counting the ... and compact and measures accurate reading. The maximum measuring length of digital tape is 4.8m 

Description : What are the objectives of following one each. i)Topographic Survey ii)Cadastral Survey iii)Engineering Survey iv)Mine Survey

Last Answer : i) Topographic Survey : To determine natural features like river, streams , lakes , hills etc and artificial features like roads , railways , canal , town and villages .  ii) Cadastral ... Mine Survey :To explore mineral deposits and to guide tunneling and other operations associated with mining. 

Description : Draw Conventional symbol for i) Embankment ii) Pond or Lake iii) Tunnel iv) Compound Wall

Last Answer : Conventional symbol for i) Embankment ii) Pond or Lake iii) Tunnel iv) Compound Wall

Description : Define Change point and its necessity in leveling.

Last Answer : Change point : It is the point at which both backsight and foresight readings are taken before and after shifting the level instrument. Necessity of change point in leveling : It is ... observations from single station due to large area, abrupt ground level variation and unavoidable obstruction. 

Description : Define horizontal line and vertical line.

Last Answer : Horizontal line : A straight line tangential to the level line and perpendicular to the plumb line is called horizontal line.  Vertical line : A line perpendicular to horizontal line and coinciding plumb line is known as vertical line

Description : Define local attraction. State two causes of local attraction.

Last Answer : Local attraction: It is the deviation or deflection of magnetic needle from its normal position under influence of external magnetic forces is called as local attraction. Causes of local attraction : 1. Iron ... structure 2. Electric cable line 3. High voltage current 4. Bunch of key 5. Steel Tape 

Description : Define : i) Traversing ii) Magnetic Meridian

Last Answer : i) Traversing : Traversing is the series of survey lines connecting successive established traverse stations along the route of survey  ii) Magnetic Meridian : The direction indicated by ... and properly balanced Magnetic needle unaffected by local attractive force is called magnetic meridian.

Description : What is fly levelling? When it is carried out?

Last Answer : Fly levelling- It is the levelling operation in which only BS and FS are taken and no intermediate sights are observed. It is carried out when 1. To connect the BM to the starting point of ... BM. 3. To determine approximate reduced levels of points carried out with more speed and less accurate.

Description : What is bench mark? State the types of bench mark and explain any one type.

Last Answer : Bench Mark- It is fixed reference point of known or assumed elevation. Types of bench mark1. Great trignometrical survey bench mark 2. Permanent bench mark 3. Arbitrary bench mark 4. Temporary bench ... Karachi are given in catalogue formed by department. They are also known as G.T.S. Bench mark

Description : Describe back sighting method of orientation of plane table surveying.

Last Answer : Backsight method of orientation 1. Assume we have to orient the table at next station B' represented on paper by point b'. 2.the line ba' is drawn on previous station A'. 3.the alidade is kept ... A'. 4. When the plotted line ab' coincides with line AB' and table will be oriented.

Description : What is open traverse and closed traverse?

Last Answer : a) Open traverse - 1. When starting point of survey does not coincide with last point of the survey, it is known as open traverse. 2. It is used for the survey roads, rivers coastal line railways ... traverse. 2. It is suitable for the survey of boundaries of ponds, forests, estate, etc.

Description : Define true bearing and magnetic bearing.

Last Answer : 1. True bearing – (i) The angle between true meridian or geographical north and any line known as true bearing. 2.Magnetic bearing-(i)The angle between magnetic meridian and any line is known as magnetic bearing.

Description : Describe quadrantal bearing system. State the purpose it is used. 

Last Answer : Quadrantal Bearing - 1. The magnetic bearing of line measured clockwise or anticlockwise from north or south pole whichever is nearer. 2. These bearings are also called as reduced bearings. 3. ... lines in a closed traverse. 2. It is used to calculate back bearing for respective quadrants.

Description : Draw a neat lebelled sketch of optical square. Explain its working.

Last Answer : Working of optical square1. Optical square works on principle of optical square to set perpendicular offset 2. Keep ranging rods at point B and C as shown in fig. 3. Observe the ... matched each other point D can be marked on ground and distance CD is measured as perpendicular offset.