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ENGINEERING SURVEYING - Coggle Diagram

- - - - Deflection Angle Method
  - - - Supposing two straights are connected by a
        circular curve
      - The circular curve is partly replaced by two transition curves at each end (at the beginning and ending sections) as combined curve
  - - - Crest curve - grade meeting at summits
        
        Grades are represented in terms ratio or percentages;
        grade 1:40=2.5%
        
        Sag curve - grades meeting at valleys
      - Rising grades are written as +ve (e.g.+5%)
        and those descending as -ve (-5%)
      - In vertical curve designs, calculations are based on the algebraic difference between gradients
      - Gradients increasing in the direction of chainage are given +ve sign and those decreasing are -ve
  - - - The reduced level (RL) of chainage points needed are calculated and pegs/markers are driven to indicate cut and fill
      - Therefore, setting-out data are chainages whose reduced levels represent the finished level (surface of the proposed road)
    - - Length of the curve (2 methods)
        
        Based on vertical radial force
        
        Based on the sighting distance (S)
      - Length of curve (2l) based on vertical radial force; 2L (total length) = ((p+q)*(v^2)) / (100f)
        
        Length of curve (2L) based on the sighting distance (S) - 3 cases are possible
        
        S > 2L
        
        S < 2L
        
        S = 2L
      - The position of the highest point on the
        curve from the tangent point;
        x = (2p/ p+q) * L
- - - - Radiation by Tacheometry
        
        Details are measured from a control point (station) that is closest to the area to be mapped
        
        provide hori & verti distances at accuracies suitable for detail surveys
        
        Distances obtained by tacheometry are of low order accuracy, therefore, is suitable to be used for producing plans at scales less than 1 : 200
        
        Fieldwork
        
        Select one of the adjacent station as the reference object (RO) and if possible set the horizontal angle to zero ; all angles will be relative to this RO
        
        When the staff is at a point of detail, observe and record the three stadia hairs, horizontal and vertical angles (nearest 1minute is sufficient)
        
        Set-up instrument over station & record the height of instrument (height of the trunnion axis from the ground)
        
        The procedure is repeated for all details needed and as a precautionary measure, it is sensible to check the reading to the RO from time to time
      - Radiation by EDM/Total Station
        
        Details are measured either using an EDM mounted on a theodolite or a total station (EDM+theodolite+on-board software)
        
        This method of picking-up details is closely
        linked to computer-aided mapping
        
        Recap : EDM is an electronic distance measurement method that is capable of providing horizontal and vertical distances at high accuracies
        
        Data observed are normally entered or downloaded to computers and processed using an engineering surveying software to produce the required plans
- - - - EXAMPLES
      - METHODS
        
        Angular Misclosure
        
        Total required angle = (Final forward bearing - Initial back bearing) + (m * 180 degree)
        
        *where :
        
        m is an integer, in most cases, m will be (n-1) or n or (n+1)
        
        n is the no. of left-hand angles observed
        
        note : value of m is obtained by assuming that observations are gross-error free
        
        Angular Misclosure & Angle Adjustment
        
        Calculate :
        
        Latitude and departure
        
        Linear misclosure and adjustment of latitude and departure
        
        Forward bearing
        
        Coordinates of certain stations
        
        Angular misclosure and Angular correction
        
        Initial back bearing and final forward bearing
        
        Forward Bearing Calculation
        
        Latitude/departure calculation (Linear misclosure 1:10,000)
        
        Latitude/departure correction (Linear misclosure 1:10,000)
        
        Latitude/departure adjustment (Linear misclosure 1:10,000)
        
        Coordinate calculation
      - OBJECTIVES
        
        To find treasure point (unknown point) based on coordinate given
        
        To perform the calculation of traverse on the spot when the fieldwork is done
        
        To apply the concept of link traverse in searching the exact location of the traverse
      - EQUIPMENT
        
        Tripod
        
        Total station
        
        Prism
    - - EXAMPLES
      - METHODS
        
        Angular Misclosure (AM)
        
        The observe angles can be internal/external angles
        
        AM are found by comparing the sum of the observed angles with one of the following theoretical values :
        
        Internal angles required = (2n - 4) * 90 degree
        
        External angles required = (2n + 4) * 90 degree
        
        *where n is the no. of angles measured
        
        Linear Misclosure
        
        Latitude/departure correction
        
        Latitude/departure adjustment
        
        Latitude/departure calculation
        
        Coordinate calculation
        
        Area calculation (coordinate method)
      - OBJECTIVE
        
        To establish the horizontal control points for uses in detail survey
        
        To act as a preparation for the land reclamation
      - EQUIPMENT
        
        Total Station
        
        Tripod
        
        Prism