from the adjustment. And this It is a short traverse, with a large closure which has to be to a high degree of accuracy, I consider that Bowditch’s Rule used in. BOWDITCH TRAVERSE ADJUSTMENT AND. A MODIFICATION. THErationale of the Bowditch method of adjusting a traverse is possibly unknown to some of. Adjust angles or directions; Determine bearings or azimuths; Calculate and adjust latitudes and departures Adjustments applied to angles are independent of the size of the angle; Methods of adjustment: Compass (Bowditch) Rule.
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There are two types of traverse surveying i.
Angles observed to side points are not subject to adjustment. If the traverse is not a loop that closes back to the start, a closure back to the start is adjksting to obtain the area – in such a case, Invalid if lines cross is printed in the Traverse Summary following the area value to indicate that the area relies upon the assumption that it is a valid enclosure.
Enclosed area – If a traverse section is adjusted, a value travetse be calculated for the enclosed area. If a more rigorous adjustment is required, then the Least-Squares Network adjustment is recommended.
Bowditch Traverse Adjustment [Bowditch導線平差]
Metgod a series of connected lines form a closed circuit, ie. Traverse Correction – Bowditch Method In Traversing the lengths of the line are measured by chain or a tape and the directions are fixed by the compass or theodolite or by forming angles with chain and a tape. Subsequent traverse sections within the same set of rtaverse, which commence at points either traverse stations or side-shot points, and either adjusted or not computed in any previous traverse section, do not require that their start lf be specified as fixed; in fact, the points should not be fixed if they are ‘adjustable’ points, as fixing will upset prior traverse adjustment.
If the closing line or any other traverse line crosses over the traverse route, the area computed will be invalid. In Traversing the lengths of the line are measured by chain or a tape and the directions are fixed by the compass or theodolite or by forming angles with chain and a tape. The steps are as described below….
Traverse Adjustment – Bowditch method
In a self-closing loop, the closing angle may be turned either onto a line within the loop, or onto a line on a previous section mwthod the traverse leading into the loop.
Refer to Traverse Types for diagrams of possible traverse configurations.
These instruments are also capable of recording and string or distances and angles replacing the conventional methods. The hypotenuse of a right triangle whose sides are the misclosure in latitude and the misclosure in departure.
When the finishing point coincides with the starting point, then it is called as a closed traverse. The current traverse section is re-run, travrse the required correction to each traverse angle. No variation to the method of linear adjustment is made for traverses computed on spheroid – it is considered that the method described is adequate for engineering-type surveys.
These closed traverse surveys has many applications like fixing the boundaries of ponds, forests etc. The latest instruments like total station captures the co-ordinates of the points along with elevations.
Present techniques used in traversing using total station as a open traverse. However, in order to distribute the misclose more in keeping with the anticipated variable reliability of angle observations over lines of differing lengths, the amount of misclose adjustment applied to each angle is proportional to the sum of the inverse lengths of the backsight and foresight lines:.
When the start of a new traverse section is detected by the software, all points bowdifch to the new start are held as fixed for the purpose of allowing the adjustment if necessary of subsequent sections – i.
Closed Traverse and Open Traverse. Any traverse, or a new section which does not commence at a point fixed in a previous section within the same set of data, must have at least one point the first instrument station specified as a fixed point refer to the heading Fixed Points under Enter Points and also close onto a fixed ajusting in order that the section be able to be adjusted; if the start point is not fixed or held fixed from a previous traverse section the traverse will still compute but cannot be adjusted.