What is traversing?
Survey that measuring distances and angles of connected straight lines by travers stations to determine 2D coordinates.
Types of traverse
Closed traverse (mathematically closed) :
- link ( geometrically open)
- loop ( geometrically closed)
- network (redundant observation
Open traverse (geometrically open, mathematically open)
Explain closed traverse
Divided into:
- link, lines finish upon another point (initial and last point has other point/reference direction to close)
- loop, lines returning to starting point
- network, interconnection of stations to create redundant observations (more mathematical check)
Explain open traverse
Connected lines but do NOT RETURN to the starting point or any other point.
Observation of traverse angles or directions
- Traversing by interior angles - should be measured clockwise from the backsight to the foresight
- Traversing by angles to the right - when the traverse is not a loop
Types of horizontal angles
- Interior angles, the inside of a closed polygon. The sum of interior angle = (n-2)*180
- Exterior angles, the outside of closed polygon. The sum of interior and exterior must total 360
- Angles to the right, measured clockwise from the backward to the forward (stations are counterclockwise numbered). Most used
Guidelines to select traverse stations
- Intervisibility, between adjacent stations and must be clear to the forward and back
- Accessibility, stations should be set in convenient locations
- Efficiency, stations are placed to creat lines as long as possible.
How do we measure the angle misclosure?
The difference between the sum of observed angle and the (n-2)180 angle
Permission misclosure C=Ksqrtn
K=30 , n= banyak sudut
Radial traversing steps
- Put a point O where it can be visible to all points
- After backsighting the control points, the other’s azimuth and lengths are known.
- Coordinates can be measured.
How to check the result of radial traversing
By putting other O point that is visible to every point then compare the results.
What is the advantage and disadvantages of radial traversing
It is good to measure a large number of points and also rapid, and can calculate all of the angle, coordinates, and distance in real time.
But, it’s not as robust as closed traverse
Source of error in traversing
Poor selection of stations, that results to:
Alternate sun and shadow
Visibility of only rod’s top
Lines too short
Line of sight too close to ground or close to other object caused refraction
Sighting into the sun
Mistakes in traversing
Sighting wrong station
Incorrect orientation
Confusing angles right or left
Mistakes in noting
