SHOTS - SURVEYING

💥 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 curvature of the earth is considered. 

💥 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. 

💥 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 can be 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 in-extensible 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. 

💥 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 preferable to set the level on one side of the slope. 

💥 Dumpy level is suitable when many readings are to be 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 centering 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.