Write errors in leveling and corresponding precaution

Write errors in leveling and corresponding precaution
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1 Answer

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 – Sluggish bubble tube should be replaced by good one.

2.Erroneous divisions of the leveling staff will cause some error.

Precaution-Replace the leveling staff by standard leveling staff

ii) Manipulation error respect to parallax, leveling of instrument

1. Poor object image is appearing due to reading taken without removing parallax.

Precaution - Focussing of object glass and eye piece should be properly done.

2.Improper leveling of instrument causes serious error of incorrect reading.

Precaution- Leveling should be properly done by bringing the bubble of bubble tube at Centre.
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Tacheometric Surveying

Description : Tacheometric Surveying

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Description : Explain the temporary adjustments of prismatic compass.

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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.

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 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

State two advantages of telescopic alidade over simple alidade.

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.

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.

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

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.