thus making all calculations obvious. 6. Finally, tabulate the adjusted bearings of the traverse. Refer to the accompanying sample format shown below. ADJUSTED BEARINGS LINE LENGTH FORWARD ВАCK АВ ВС CD DE EA VI. ILLUSTRATIONS:
My Course subject is fundamentals of surveying.
this is now complete, please help me answer this one Thank you!
I. PROCEDURE
- Establish at least six traverse stations at designated points on the field assigned to be
surveyed. Call these stations (or corners) A, B, C, etc. - Set the instrument
- Sight instrument on the last traverse station and read the magnetic bearing.
Record this as the back bearing of the line in the traverse.
4. Sight B and read the instrument. Record this as the forward bearing of line AB.
5. Transfer the instrument to B. Sight on A and read the instrument and record this as the back bearing of line AB.
6. Proceed to the next station and repeat the above procedure of determining back and forward bearings for each line. Continue until the last traverse station is occupied and the forward bearing of the last line has been read and recorded accordingly.
7. With a plastic tape, measure the length of each line in the traverse.
8. Tabulate observed and adjusted values accordingly.
LINE |
LENGTH |
OBSERVED BEARING |
|
FORWARD |
BACK |
||
AB |
46.5m |
S 30o40’ W |
N 30o40’ E |
BC |
75.15 |
S 83o50’ E |
N 84o30’ W |
CD |
117.35 |
N 02o00’ W |
S 02o 15’ E |
DE |
74.92 |
S 89o30’W |
DUE EAST |
EA |
60.25 |
S 28o50’ E |
N 28O00’W |
COMPUTATIONS
- The interior angle at each station of the traverse can be computed easily from the observed forward and back bearings taken from the station regardless of whether or not the needle is affected locally. A carefully prepared sketch is important since from it the required calculations will be obvious.
- The angular error of closure is determined by subtracting the sum of the computed interior angles of the traverse from (n-2)180O, where n is the number of sides in the traverse. Note that the computed value may be positive or negative quantity, and the resulting sign should be considered in all succeeding computations.
- The correction for each computed interior angle is determined by dividing the angular error of closure by the number of traverse stations. This computed value is then added algebraically to each computed interior angle to determine the corresponding adjusted interior angle.
- Go over the observed bearings and determine which line in the traverse is free from local attraction or which could be arbitrarily chosen as the best line. The adjustment of traverse lines affected by local attraction is then made by starting from the unaffected or best line.
- The forward and back bearings of all other lines in the traverse affected by local attraction can then be easily computed and adjusted by again drawing a sketch thus making all calculations obvious.
- Finally, tabulate the adjusted bearings of the traverse. Refer to the accompanying sample format shown below.
LINE |
LENGTH |
ADJUSTED BEARINGS |
|
FORWARD |
BACK |
||
AB |
|
|
|
BC |
|
|
|
CD |
|
|
|
DE |
|
|
|
EA |
|
|
|
Step by step
Solved in 6 steps with 5 images