LESSON 6

• TRAVERSE - consists of a series of straight lines connecting successive points whose lengths and directions have been determined from field observations.
• TRAVERSE STATIONS OF TRAVERSE POINTS - points defining the ends of traverse lines.
• PURPOSES OF TRAVERSE


  Property surveys to locate and establish boundaries

  Supplementary horizontal control for topographic mapping survey

  Location and construction layout surveys for highways, railways, and other private and public works.

  Ground control surveys for photogrammetric survey.
• GENERAL CLASSES TRAVERS

  Open Traverse

  Closed Traverse

  • Closed Loop Traverse
• Open Traverse - originates at a point of known position and terminates at a point of unknown position.
• Closed Traverse - originates at a point of known position and terminates at a point of known position.
• Closed Loop Traverse - a closed traverse that originates and terminates at a single point.
• OPEN TRAVERSE

  
• CLOSED TRAVERSE

  
• CLOSED LOOP TRAVERSE

  
• TYPES OF TRAVERS

  Deflection-angle Traverse

  Interior-angle Traverse

  Traverse by angles to the right

  Azimuth Traverse

  Compass Traverse
• TRAVERSE COMPUTATIONS - In dealing with a closed traverse, we have computations in:


  Determining latitudes and departures

  Calculating total error of closure

  Balancing the survey

  Determining the adjusted positions of traverse stations

  Area of Computation

  Area of subdivision
• LATITUDE - projection of a line onto a reference meridian or North-South line.
• ✓ Lines with Northerly bearings→ (+) LAT
• ✓ Lines with Southerly bearings→ (-) LAT
• FORMULA OF LATITUDE

  
• DEPARTURE - projection of a line onto a reference parallel or East-West line.
• ✓ Lines with Easterly bearings→ (+) DEP
• ✓ Lines with Westerly bearings→ (-) DEP
• FORMULA OF DEPARTURE

  
• LINEAR ERROR OF CLOSURE - is usually a short line of unknown length and direction connecting the initial and final traverse stations.
• FORMULA OF LINEAR ERROR OF CLOSURE

  
• RELATIVE ERROR OF CLOSURE - Ratio of the linear error of closure to the perimeter or total length of the traverse.
• FORMULA OF RELATIVE ERROR OF CLOSURE

  
• TRAVERSE ADJUSTMENTS - methods of adjustments are usually classifies as:

  Rigorous

  • Least Squares Method

  Approximate

  • Compass Rule (Bowditch Rule)
  • Transit Rule
  • Crandall Method
• Compass Rule - named after the distinguished American navigator Nathaniel Bowditch (1773-1838).
• Compass Rule - named after the distinguished American navigator Nathaniel Bowditch (1773-1838).
• COMPASS RULE - based on the assumption that:


  All lengths are measured with equal care.

  All angles taken with approximately the same precision.

  Errors are accidental

  Total Error in any side is directly proportional to the length of the traverse.
• FORMULA ADDITIONALLY IN COMPASS RULE (BOWDITCH RULE)

  
• TRANSIT RULE - No sound theoretical foundation since it is purely empirical.
• TRANSIT RULE - Not commonly used but best suited for surveys where traverse sides are measured by stadia or subtense-bar method.
• TRANSIT RULE - Not commonly used but best suited for surveys where traverse sides are measured by stadia or subtense-bar method.
• TRANSIT RULE - based on the assumption that:

  Angular measurements are more precise than linear measurements

  measurements.

  Errors in traversing are accidental.
• FORMULA ADDITIONAL TO TRANSIT RULE

  
• SIDE SHOTS - Ties from the adjacent traverse to the original points.
• PLANE SURVEYING - area is taken as its projection upon a horizontal plane.
• GEODETIC SURVEYING - area is taken as its projection upon the earth’s spheroidal surface at MSL.
• METHODS OF AREA OF COMPUTATION

  Triangles

  Coordinate Method

  DMD-DPA OR DPD-DPA

  Trapezoidal Rule

  Simpson's one-third rule
• AREA BOUNDED BY REGULAR BOUNDARIES

  Area by Triangles

  Coordinate Method

  DMD-DPA or DPD-DPA
• AREA BY TRIANGLES

  Known Base & Altitude