Mr. Education

SURVEYING INSTRUMENTS We are discussing intruments like total station, theodolite, EDMI and military compass. 1. Total Station: A total station is an electronic and optical instrument used in modern surveying and is designed for measuring slant distances, horizontal & vertical angles, elevation, i.e, it is the combination of EDMI and theodolite. Parts of Total Station : Alidade : used for rough alignment. Focusing Knobs : used in focusing the target object  Eye-piece : used to see the object. Leveling Screws : used to level the instrument. Display Panel : the screen where the data is shown. Clamps : they are used to lock down the vertical and horizontal motion. Optical Plummet : used for centering the instrument. Working : Set the total station on a station by leveling and centering. Switch on the machine and rotate the machine once in horizontal and once in vertical position to activate the machine. Then check the leveling on the screen by press...

Angles & Directions Angles are also called bearings. Bearings are the acute angles between lines and meridians. They are divided into following types. Related Terms : Meridian : Imaginary line joining North and South poles. Declination : Difference between magnetic and true meridians. Azimuth : Clockwise angle taken from Geodatic North. * If area is greater ➤ use Geodatic North * If area is smaller ➤ use Magnetic North Magnetic Declination maybe towards East or West. For east     ➤       Magnetic bearing=true bearing - Declination For west    ➤       Magnetic bearing=true bearing + Declination Forward Bearing : Bearing taken in the direction of traverse. Backward Bearing : Bearing taken in opposite direction of traverse. Forward bearing - Backward bearing=180 For anti-clockwise :  FB of line = BB of previous line + angle Example: In an anti-clockwise traverse <A=102'30',...

LEVELING Definition : The procedure for determining differences in elevation between points that are some distance away from each other is called Levelling. Types Of Leveling : There are many types but we discussed some of them here.  1. Differential Leveling : It is used to determine the differences in elevation between points that are some distance away from each other by level together with a graduated measuring rod. 2. Reciprocal Leveling : Reciprocal leveling is employed to determine the difference in elevation between two points when it is difficult to keep back sight(B.S.) and fore sight(F.S.) short and equal. 3. Profile Leveling : It is a method of surveying that has carried out along the central line of a track of land. 4. Cross-section Leveling : A profile leveling in which we determine the elevation of series of points or lines at right angle to lengthwise along a highway.  Bench Mark Leveling ➤ using Bench mark for ...

TAPING CORRECTIONS There are two types of corrections depending upon the type of errors in tape due to the different conditions.  1. Systematic Errors : Slope Erroneous tape length Temperature Tension Sag 2. Random Errors : Slope  Alignment Marking & Plumbing Temperature Tension & Sag 1. Temperature Correction  It is necessary to apply this correction, since the length of a tape is increased as its temperature is raised, and consequently, the measured distance is too small.  It is given by the formula,                         C t  = 𝛼 (T m  – T o )L Where,   C t  = the correction for temperature, in m.      𝛼 = the coefficient of thermal expansion.    T m  = the mean temperature during measurement.          T o  = the tempe...

METHODS OF DISTANCE MEASUREMENT There are many methods for the measurement of distance.  1. Pacing : Pacing is a very useful but imprecise technique of distance measurement. First of all, the one who wants to measure distance should measure distance between his feet and then make a walk up to which distance is to be measured.  Total distance = distance between 2 feet × No. Of pacing 2. Odometer : Odometer is an instrument used to measure distance in wheel based vehicles. The most important for distance measurement is to find out the radius of wheel and the number of rotation. Then using the following formula for distance measurement.  Total distance = Radius of wheel × No. of rotation                         H = R × θ 3. Electronic Distance Measurement (EDM) : EDM is used for measuring distance electronically between two points through electromagnetic waves.  EDM have f...

ENGINEERING SURVEY Surveying is the science, art and technology of determine the relative positions of points above, on or beneath the Earth's surface so as to construct a map, plan or description. TYPES OF SURVEY : There are many types of survey but we discuss some of them.  1. Plane & Geodatic Survey : Ordinary field and topographical surveying in which the Curvature of Earth's surface is disregarded is called Plane Survey. It is performed when the area is smaller than 250sq.km.  A survey of a large land area in which corrections are made for the Curvature of Earth's surface is called Geodatic survey.  Why Geodatic Survey is important? Earth's surface is not flat, it is sphere. So all the calculations which were made by considering the Earth's surface flat are incorrect. So a new type of survey came into play which made calculations on the basis of geodatic condition of Earth's surface.  2. Topographic Survey : Topographic surv...

ADVANTAGES OF HYDROGRAPHIC SURVEY Accurate hydrographic survey and nautical charts yields many social benefits and contribute alot in making our life even more luxurious. 1.Safety of navigation is the single most important result of hydrography. This allows ships to safely travel in and out of ports, saving lives and property and protecting the environment.   2. National Security requires that navies successfully navigate coastal waterways. 3. Maritime commerce drives the global economy and depends on safety of navigation. 4. Humanitarian relief in the aftermath of a natural disaster frequently arrives on a ship. Until a clear and safe route to shore is established by hydrographers, supplies cannot reach those in need. 5. Environmental management in coastal areas depends on knowledge of changes in the marine environment. Hydrographic surveys determine changes to bathymetry and seafloor characteristics. 6. Commercial fishing uses nautical charts...