Surveying notes for GATE, PSUs - Part 6

Hello there,
How have you been? Here is 6th part of one liners for the preparation of the GATE and PSUs.

• In Levelling, a station is the point where the levelling staff is held and not where level is set up.
• The inner surface of a bubble tube is an arc of a circle.
• Sensitivity of a level tube can be increased by the increase in length of bubble.
• Dumply level is most suitable when a numbers of readings are to be taken from single setting of the instrument.
• The difference of levels between two stations A and B is to be determined. For best results, the instrument station should be equidistant from A and B.
• contour interval is inversely proportional to the scale of the map.
• An imaginary line lying throughout the surface of ground and preserving a constant inclination to the horizontal is known as contour gradient.
• Two contours of different elevations do not cross each other except in case of an overhanging cliff.
• A series of closely spaced contour lines represents a steep slope.
• Direct method of contouring is most accurate method.
• In direct method of contouring, the process of locating or identifying points lying on a contour is called vertical control.
• In the cross section method of indirect contouring, the spacing of cross-sections depends upon contour interval, scale of plan and characteristics of ground.
• For hilly terrains Tacheometric method of contouring is most suitable.
• contour interval for any map is kept constant.
• Closed contours, with higher values inside represents a hillock.
• Benchmark is established by spirit leveling.
• Plane table is the type of survey which requires least office work.
• Intersection method of detailed plotting is most suitable for hilly areas where the points are not accessible.
• Detailed plotting is generally done by radiation method.
• Three point problem can be solved by Tracing paper method, Bessels method and Lehman's method.
• The size of a plane table is 600 mm * 750 mm.
• The process of determining the locations of the instrument station by drawing resectors from the  locations of the known stations is called resection
• Plumbing fork is used for accurate centering of plane table.

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