Describe instrumental errors in leveling.

Describe instrumental errors in leveling.
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1 Answer

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 permanent adjustment, the line of collimation may be inclined upward or downward causing serious errors. The line of collimation may not be parallel to the axis of bubble tube. Axis of telescope may not be perfectly perpendicular to vertical axis. These instrumental errors lead to errors in leveling. 2. Less sensitivity of bubble or bubble is sluggish: If the bubble is not sensitive or it is sluggish, it may apparently be in the center though the bubble line is not horizontal. 3. Faulty focusing tube: Sometimes the focusing tube is faulty. Due to this the objective does not move in horizontal plane but moves in inclined direction during focusing. This is compensatory error and can be eliminates by balancing back sight and fore sight. 4. Errors in leveling staff: The graduations of the leveling staff may not be perfect. These errors can be neglected for ordinary work.
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Description : State sources of error in leveling. 

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Description : Describe in brief errors in compass survey.

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

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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.

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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 

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

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

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Describe stepping method of chaining on sloping ground.

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Description : State and describe the types of offsets. 

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Description : Describe in brief profile levelling.

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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.

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Description : Describe in brief obstacles in chaining.

Last Answer : There are 3 types of obstacles 1. Obstacle to ranging 2. Obstacle to chaining 3. Obstacle to both ranging & chaining. 1) Obstacle to Ranging: The type of obstacle in which the ... type of obstacle the problem lies in prolonging the line beyond the obstacle & determining the distance across it.

Describe in brief with neat sketch: i) Base line ii) Check line

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Describe in brief process of chaining on sloping ground.

Description : Describe in brief process of chaining on sloping ground.

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Describe in brief primary classification of surveying

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What is changing face

Description : As used in survey

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The process of surveying is therefore in three stages namely:

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.

Tacheometric Surveying

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.

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. 

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

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.

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

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. 

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

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

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.

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.

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

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. 

Define: WCB and Quadrantal Bearing system

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 .

State the two uses of survey based on geodetic surveying

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.

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

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.

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.

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

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.

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