Explain errors occurred due to manipulation and sighting in plane tabling.

Explain errors occurred due to manipulation and sighting in plane tabling.
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1 Answer

Answer :

i) The board not being horizontal- This error affects chiefly the measurement of vertical angles.

ii) The table not being accurately centered. The plotted position of the occupied station not being exactly over the station on the ground.

iii) The table not being correctly oriented. To prevent this error, the orientation of the table should be checked at as many stations as possible by back sighting or by magnetic meridian.

iv) The table being displaced from its initial position. There is likely to be slight rotation or other displacement of the table. Frequent check sight should be taken to detect and correct any displacement.

v) The defective sighting- The object not being correctly sighted.
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Related questions

What are the sources of errors in plane tabling?

Description : What are the sources of errors in plane tabling?

Last Answer : The following are the sources of errors in plane tabling 1) The board not being horizontal 2) The table not being accurately centered 3) The table not being Correctly oriented 4) The objects ... through the station point 7) Inaccuracy in plotting 8) The expansion and contraction of the paper 

Explain Orientation of plane table by Back-sighting Method.

Description : Explain Orientation of plane table by Back-sighting Method.

Last Answer : Ans:- The method of setting up the plane table at each of the successive stations parallel to the position it occupied at the starting station is known as an Orientation. Orientation must be done when ... and bisection of the ranging rod at a are perfect then orientation is said to perfect.  

Describe back sighting method of orientation of plane table surveying.

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.

Explain with neat sketch the procedure of radiation method of plane tabling.

Description : Explain with neat sketch the procedure of radiation method of plane tabling.

Last Answer : 1. The table is set at suitable station e.g. P from where all stations can be sighted and measured. 2. After centering and leveling, mark station P as P' on sheet. 3. Suppose stations A, B, C, and D are ... marked as pa. 5. Similarly station B, C and D are bisected and marked as b, c and d.

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

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.

Define orientation and principle of plane tabling.

Description : Define orientation and principle of plane tabling. 

Last Answer : Orientation: The orientation of plane table means keeping the plane table at all stations parallel to the position it occupied at first station. Principles of plane table survey: 1. The rays drawn from ... same as that of previous station i.e. orientation should be done at each changed station.  

Enlist the methods of plane tabling.

Description : Enlist the methods of plane tabling. 

Last Answer : Method of Surveying with the plane table are : 1) Radiation 2) Intersection 3) Traversing 4) Resection

What is meant by orientation? Explain orientation by back sighting method

Description : What is meant by orientation? Explain orientation by back sighting method

Last Answer : Orientation: The method of setting up the plane table at each of the successive stations parallel to the position it occupied at the starting station is known as orientation. Orientation by back sighting: ... ranging rod at A are perfect, then the orientation is said to be perfect.  

Describe in brief errors in plane table survey.

Description : Describe in brief errors in plane table survey.

Last Answer : 1) The board not being horizontal. 2) The table not being accurately centered. 3) The table not being Correctly oriented. 4) The objects not being sited accurately. 5) The alidade not being ... through the station point. 7) Inaccuracy in plotting. 8) The expansion and contraction of the paper.

Write errors in leveling and corresponding precaution

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.

State any four sources of errors in compass survey

Description : State any four sources of errors in compass survey 

Last Answer : Following are the sources of errors in compass survey1. Instrumental survey-  a. Needle may not be perfectly straight and might not be balanced properly over the station.  b. Graduations of the rings ... substances near the station.  b. Magnetic field may vary on account of some natural causes. 

Enlist different errors in compass surveying.

Description : Enlist different errors in compass surveying.

Last Answer : Various errors in compass surveying are classified asi) Instrumental errors. ii) Personal errors or observational errors iii) Errors caused due to external errors (natural errors) i) ... magnetic declination. c) Local attraction due to proximity of magnetic substances or magnetic field.

Describe instrumental errors in leveling.

Description : Describe instrumental errors in leveling.

Last Answer : The leveling process requires two instruments namely level and staff. The instrumental errors related to these are1. Error due to imperfect permanent adjustment: When the instrument is not in perfect ... the leveling staff may not be perfect. These errors can be neglected for ordinary work.

Describe in brief errors in levelling.

Description : Describe in brief errors in levelling. 

Last Answer : The sources of error in levelling are as below 1) Instrumental errors: Error due to imperfect adjustment, Sluggish bubble, Faulty Focusing tube, Erroneous leveling staff. 2) Personal errors: ... length. Use umbrella to shelter the instrument, use sun shade, avoid levelling work during wind. 

Describe in brief errors in compass survey.

Description : Describe in brief errors in compass survey.

Last Answer : Errors in Compass Surveying. The errors are classified as: 1. Instrumental errors. 2. Personal or Observational errors. 3. Errors due to External Influences (Natural errors etc.).  (1 ... in magnetic declination. (iii) Local attraction due to proximity of electric lines, steel structures etc.

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

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.

Explain the radiation method of plane table survey with neat sketch.

Description : Explain the radiation method of plane table survey with neat sketch. 

Last Answer : This method is used when all the points to be plotted are visible from single instrument station. Steps are: 1. Select a suitable point P on the ground such that all the details are visible from it. 2. Center and ... , pc, pd, pe respectively. Join a, b, c, d, and e to give the outline.

Explain ‘Intersection Method’ of plane table surveying with neat sketch. Also give situation when intersection method is used.

Description : Explain ‘Intersection Method’ of plane table surveying with neat sketch. Also give situation when intersection method is used.

Last Answer : 1. Lay out a base line AB and measure it and Plot a distance ab' on sheet using any scale. 2.Set up instrument at A' with a' over A' 3.Orient the table by placing alidade ... the case of the survey of mountainous country. 5. The only linear measurement required is that of a base line.

Explain intersection method of plane survey.

Description : Explain intersection method of plane survey.

Last Answer : Intersection method of plane tabling 1. Lay out a base line AB and measure it and Plot a distance ab' on sheet using any scale. 2.Set up instrument at A' with a' over A' 3.Orient the table by ... sighted rays bd, bg, bf, bc are drawn to determine points intersection, d, g, f, c.

Explain temporary adjustment of plane table survey.

Description : Explain temporary adjustment of plane table survey.

Last Answer : 1. Setting over the station: The plane table is fixed on tripod and adjust the table in such a way that table is approximately level. 2. Leveling the table: The tubular or spirit level is placed in two ... . The table can be oriented in two ways. i. Using trough compass. ii. By back sighting.

State the situation where plane table is suitable.

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.

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

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

State any two uses of Plane Surveying.

Description : State any two uses of Plane Surveying. 

Last Answer : 1) Plane surveying is used for measuring small distance. 2) When area is less than 260 km2, plane survey is normally done. 3) When desired accuracy is less, plane survey is done.

State merits and demerits of plane table survey.

Description : State merits and demerits of plane table survey. 

Last Answer : Merits: 1) It is the most rapid method of surveying.  2)There is no need for field book as plotting is done along with the field work, so the problem of mistakes in booking field notes does not arise. ... to carry. 5) The map cannot be replotted to defferent scale as there is no field book. 

State the use of alidade in plane table surveying

Description : State the use of alidade in plane table surveying

Last Answer : 1) It is used for sighting the objects to be located.  2) It is used for drawing the rays. 

Compare collimation plane method and rise and fall method of reduction of levels.

Description : Compare collimation plane method and rise and fall method of reduction of levels.

Last Answer : The comparison between collimation plane method and Rise and fall method is given below. Collimation plane method Rise and Fall method 1 1. It is rapid method as it involves few calculations. ... Arithmetic check in this method is ΣBS - ΣFS = ΣRise - ΣFall = Last RL - First RL

What is orientation of plane table? State the procedure of any one method of orientation.

Description : What is orientation of plane table? State the procedure of any one method of orientation.

Last Answer : Orientation of plane table: It means placing table in parallel positions at all stations (or at successive station) 1. Orientation using trough compass: Here north direction is marked at first station ... rotated till ranging rod at previous station is exactly bisected. The table is then clamped. 

Differentiate between plane and geodetic survey on any four points.

Description : Differentiate between plane and geodetic survey on any four points. 

Last Answer : Difference between Plane Surveying and Geodetic Surveying Points Plane Surveying Geodetic Surveying Definition Plane surveying is that type of surveying in which mean surface of ... Traditional survey equipment is used Precise and modern survey equipment are required

State the principle of plane table survey.

Description : State the principle of plane table survey. 

Last Answer : Principle of plane table survey 1. The rays drawn from different points should pass through a single point i.e. position of station point.  2. The position of table should be same as that of previous station i.e. orientation should be done at each changed station.

State four advantages and four disadvantages of plane table survey

Description : State four advantages and four disadvantages of plane table survey

Last Answer : Advantages: 1. A field book is not required. 2. Errors of booking in field book avoided. 3. Errors of plotting can be readily checked. 4. Suitable in magnetic area. 5. Survey work with ... cannot be done in rainy season. 5. Difficult to re-plot as field notes are not available.

List any four accessories required for plane table survey.

Description : List any four accessories required for plane table survey.

Last Answer : 1. Plane table. 2. Plumbing U-fork. 3. Alidade. 4. Spirit level. 5. Trough compass. 6. Plumb bob.

Differentiate between plane of collimation and rise and fall method.

Description : Differentiate between plane of collimation and rise and fall method.

Last Answer : S.N Rise and fall method Plane of collimation 1 It is slow and more tedious. It is more rapid and less tedious  2 It is laborious as it involves more calculations. It is simple ... .S.-ΣF.S=ΣRise-Σfall =Last RL-First RL Arithmetical check ΣB.S.- ΣF.S=Last RL-First RL

State the limitations of plane table surveying.

Description : State the limitations of plane table surveying.

Last Answer : 1) It is not suitable for work in wet climate 2) Several accessories are required to be carried hence possibility lost. 3) Replotting of survey work to different scale is difficult in absence of ... ) It is not intended for accurate work. 6) The plane table is essentially a tropical instrument.

Describe in brief resection method of plane table surveying.

Description : Describe in brief resection method of plane table surveying.

Last Answer : This method is used for establishing the instrument stations only. After fixing the stations, details are located either by radiation or intersection. The characteristic feature of resection is that the point ... of resection are (1)The Two Point Problem, and (2)Three Point Problem.

Enlist different accessories of plane table survey with their use.

Description : Enlist different accessories of plane table survey with their use. 

Last Answer : i) The plane table: It is used for fixing a drawing sheet over it.  To locate the position of the objects on the sheet by drawing rays and plotting to suitable scale. ii) The Alidade (plain Alidade ... v) U-Fork or Plumbing fork with plumb bob: It is used for centering the table over the station. 

State the suitability of plane table survey

Description : State the suitability of plane table survey

Last Answer : The plane tabling is generally suitable for surveys in which high precision is not required. It is mainly employed for small-scale or medium size mapping.

Errors in computer results could be due to 1) encoding of data 2) transmission of data 3) manipulation of data 4) all of the above

Description : Errors in computer results could be due to 1) encoding of data 2) transmission of data 3) manipulation of data 4) all of the above

Last Answer : 4) all of the above

One of the Lehmann's rules of plane tabling, is (A) Location of the instrument station is always distant from each of the three rays from the known points in proportion to their distances (B) When looking in the direction of each of the given points, the instrument station will be on the right side of one and left side of the other ray (C) When the instrument station is outside the circumscribing circle its location is always on the opposite side of the ray to the most distant point as the inter-section of the other two rays (D) None of these

Description : One of the Lehmann's rules of plane tabling, is  (A) Location of the instrument station is always distant from each of the three rays from the  known points in proportion to their distances  ( ... to the most distant point as the inter-section of the other two rays  (D) None of these 

Last Answer : (A) Location of the instrument station is always distant from each of the three rays from the  known points in proportion to their distances 

Which one of the following procedures for getting accurate orientation is the most distinctive feature of the art of plane tabling? (A) Radiation (B) Intersection (C) Traversing (D) Resection

Description : Which one of the following procedures for getting accurate orientation is the most distinctive feature of the art of plane tabling? (A) Radiation (B) Intersection (C) Traversing (D) Resection

Last Answer : (D) Resection

While surveying a plot of land by plane tabling, the field observations (A) And plotting proceed simultaneously (B) And plotting do not proceed simultaneously (C) And recorded in field books to be plotted later (D) All the above

Description : While surveying a plot of land by plane tabling, the field observations (A) And plotting proceed simultaneously (B) And plotting do not proceed simultaneously (C) And recorded in field books to be plotted later (D) All the above

Last Answer : (A) And plotting proceed simultaneously

The instrument which is used in plane tabling for obtaining horizontal and vertical distances directly without resorting to chaining, is known as (A) Plane alidade (B) Telescopic alidade (C) Clinometer (D) Tacheometer

Description : The instrument which is used in plane tabling for obtaining horizontal and vertical distances directly without resorting to chaining, is known as (A) Plane alidade (B) Telescopic alidade (C) Clinometer (D) Tacheometer

Last Answer : (B) Telescopic alidade

The method of plane tabling commonly used for establishing the instrument station is a method of (a) Radiation (b) Intersection* (c) Resection (d) Traversing

Description : The method of plane tabling commonly used for establishing the instrument station is a method of (a) Radiation (b) Intersection* (c) Resection (d) Traversing

Last Answer : (b) Intersection*

Explain the temporary adjustments of prismatic compass.

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. 

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

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 .  

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

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

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

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.

Explain temporary adjustment.

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.

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

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 

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

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

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

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.