If required, clear any tall vegetation from the path of the traverse, so that you will be able to see each marked point from the one before it. Start passing through at the first point A. Eliminate the varying pole and stand at point A.
Point A becomes station 1. The direction you determine from there to point B, or station 2, is called a foresight * (FS) since you are determining forward.
Look back at station 1 and determine the azimuth of line BA, which is called a backsight (BS). Look forward at the next point C, or station 3, and determine the azimuth of line BC, an insight (FS).
Note these values down in the table (see action 17). BS = BA Note: the distinction between the insight and backsight must be 180. A difference of just 1 or 2 degrees in between the FS and BS is acceptable and may be fixed later on (see step 19). If the mistake is higher, you should make the measurement again before moving on to the next station.
Repeat this treatment, measuring horizontal ranges from station to station and determining 2 azimuths (a BS and a FS) for each point. From the last station at the end of an open traverse, you will only have a BS measurement, simply as you had only an FS from station 1.
6 and 4. 0). Range BC 17. You should carefully take down all the measurements you have made in a field book. You can utilize a table like the one shown in the example or you can make a rough sketch of the open traverse on square-ruled millimetric paper, noting down your measurements next to the correct stations in it.
(see Section 3. Using the known station A, compare the position of the last station X with its recognized position X'. If this comparison reveals a big error (the closing error XX'), you will require to change the observed traverse AX.
Discover azimuth AB- an insight- from the centre of this station with the compass. Measured Building Survey. Replace the varying pole exactly at station 1; 22. In a field book, thoroughly take down all your measurements. You can use a table comparable to the one suggested for the open traverse (see step 17).
At the same time, check to see that the foresights and backsights vary by 180 (Measured Building Survey). Example You have actually surveyed site ABCDEA with a closed traverse and your field notes are as follows: Stations Range (m) Azimuths (degrees) Calculated difference FS/BS (degrees) From To FS BS 1 2 90. 8 136 315 179 2 3 53.
Starting from station 1 (A), draw the observations of your compass traverse on square-ruled paper. Use a protractor to measure the azimuths (see Section 3. 3), and a sufficient scale for the measured ranges (see Area 9. 1). If there is a closing mistake, adjust your drawing by utilizing the graphic approach described for an open traverse (see step 19, above).