Ex28-1: Determine the azimuth of the sides of the open looped close traverse (Figure 28.4) by azimuth correction method. Solution : Figure 28.4 shows a deflection-angled closed traverse. It originates at point A lying on the line PQ having azimuth of 47° 53' 20" (determined from a previous survey). The traverse closes on point F lying on a line XY whose azimuth is 319° 55' 20" (also determined from a previous survey). The deflection angle observed at different stations are shown in columm (2) of Table 28.1 of a azimuths of the sides of traverse (computed using Eq 28-1) are as shown in column (3) of Table 28.1. It is found that the calculated azimuth of XY (319° 52' 20") fails to agree with its previously observed value (319° 55' 20"). Thus, there is an error of angular closure by - 3' 00" for the traverse and thus needs a corrction of + 3' 00". Since six deflection angles are measured, the correction to each angle is 30". The azimuth of AB receives a 30" correction [column (4) of Table 28.1], since this azimuth has been obtained by considering only one measured angle; azimuth of BC receives a 1' 00" correction, since this azimuth has been obtained by considering two measured angles and so on. The correction to the last azimuth is 6 x 30" = 3' 00", since this azimuth has been obtained by using all six measured deflection angles. Finally, the adjusted value of azimuth has been found (column 5) by making correction (columm 4) to computed value (columm 3). Table 28.1 Calculation of Adjusted of Azimuths of a Closed Traverse from Deflection Angles (Figure 28.4)
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||