During preparation of any government and entrance exam we can't wast our time in Reading lots of books for that purpose we need to find an trusted source of knowledge.
Theory of probability applied to accidental error only.
The difference between the most probable value and its observed value is residual error.
Geodetic surveying is different from plane surveying because of the curvature of the earth.
The error due to bad ranging is cumulative positive.
Offsets are short measurements from chain line.
Invar tape is generally used for short measurements.
An invar tape is made of an alloy of nickel and steel.
If you want to know as an respected government officer by doing MPSC AND UPSC @ free of cost then you can do your preparation by taking detailed knowledge from experts here👉👉👉
Number of links in a 30m chain are 150.
Ranging is the process of aligning the chain in a straight line between two extremities.
The principle of ‘working from whole to part’ is used in surveying because of accumulation of errors is prevented.
A metallic tape is made of cloth and wires.
For a well conditioned triangle no angle should not be less than 30’ and not more than 120’.
The position of a point can be fixed more accurately by perpendicular offsets.
The main object of check line is check the accuracy of the work and the main object of tie line is to take the details near by the objects.
River is an obstacle to chaining but not ranging.
A building is obstacle to both ranging and chaining.
The angle of intersection of the two plane mirrors of an optical square is 45’.
45’ angle is used to setup using French cross staff and any angle is set up using adjustable cross staff.
Method of perpendicular offsets involves less measurements on the ground.
The correction for sag is always subtractive.
Cross staff is an instrument used for setting out right angles.
Line ranger is not used in measuring the perpendicular offsets.
If the length of the chain is found to be short on testing it can be adjusted by straightening the links.
The maximum tolerance in a 20m chain is 5mm.
For accurate work steel band is used because it is practically inextensible and is not liable to kinks when in use.
The length of the chain is measured from outside of one handle to outside of another handle.
Prismatic compass used for WCB and surveyor compass used for QB.
For a line AB the fore bearing of line AB and back bearing of AB exactly differ by 180’.
Local attraction in compass surveying may exist due to presence of magnetic substance near the instrument.
Declination- the horizontal angle between the true meridian and magnetic meridian.
Azimuth-the angle between the true meridian and a line.
Dip-horizontal angle with respect to inclination of dip of the needle.
Agate cap is fitted with a prismatic compass.
Theodolite is an instrument used for measuring the both horizontal and vertical angles.
Size of the theodolite is specified by the diameter of lower plate.
Spire test is used for adjustment of horizontal axis.
A level line is a line parallel to the mean spheroid surface of the earth.
On turning point both back sight and fore sights taken.
In rise and fall method of levelling provides complete check on BS FS and IS.
Height of the instrument method is less tedious and quicker.
The sensitivity of a bubble tube can be increased by increasing the diameter of the tube.
While doing the levelling in undulating terrain it is preferably set the level on one side of the slope.
Dumpy level is suitable when many readings taken from single station.
A series of closely spaced contours called steep slope.
Direct method of contouring is more accurate.
Tachometric method is most suitable for hilly terrain.
Hillock-higher values inside lower values are outside.
Valley-higher values are outside and lower values are inside.
Contour interval-the vertical distance between the two consecutive contours.
Benchmark is established by spirit levelling.
Plane table surveying require least office work.
Detailed plotting is generally done by radiation.
The size of plane table is 600mm*750mm.
Plumbing fork is used for accurate centring in plane table survey.
Intersection method is used for locate the position of inaccessible points.
The two point and three point problem are the methods of orientation and resection.
Bowditch rule is used when both angular and linear measurements are equal.
Transit rule is used when angular measurements are more precise than linear measurements.
Deflection angle-the angle between the
prolongation of preceding line and the forward line.
Substance bar used for measurement of horizontal distance in undulated areas.
Over turning of a vehicle can be avoided by providing transition curves.
Different grades are joined together by vertical curve.
The shape of the vertical curve generally provided is parabolic.
Agonic line is the line joining the points of zero declination.
Altimeter-height measuring, fathometer-depth measuring, passometer-distance measuring.
Clino meter-angle measuring, pantograph-plan enlarging or reducing, tellurometer-microwave instrument.
Offsets are lateral measurements made with respect to the main survey line.
To determine the length of the bridge triangulation is used.
Heliograph is a type of sun signal is used in triangulation work.
Topographical surveying-to determine the natural features of the country.
Cadastral surveying-to determine the boundaries of field.
City survey-to determine the railway, drainage, road features of the country.
The fix of a plane table from three known points is good if the middle station is nearest.
Plane alidade is used to measure the horizontal and vertical distances directly.
If you liked this blog share , like and comments your opinion in comment box.
All the best.
For any other support from us join our WhatsApp group.-
https://chat.whatsapp.com/IDQkkfHVTvKJX7efPhITa9
Keywords # what are# surveying# Civil engineering# how#
