Errors in Chaining:
The traverse may fail to close even when angles are error free. For example the traverse starting from A is plotted as A B1 C1 D1 E1 A1 in Figure (a). The end point A1 does not coincide with A indicating closing error. If error AA1 is large, the survey has to be repeated. However, if it is small, it can be adjusted as described below.
(a) Closing Error
(b) Error Adjustment
Figure: Errors in Chaining
Plot a straight line a b1 c1 d1 e1 a1 (ab1 = AB1, b1 c1 = B1 C1 and so on) on any appropriate scale. At end a1, draw a line a1 a2 parallel to and equal to closing error AA1 and join a - a2. Draw lines parallel to a1 a2 from e1, d1, c1 and b1 (Figure (b)) to intersect aa2 at e2, d2, c2 and b2 respectively. The distances b1 b2, c1 c2, d1 d2, e1 e2 will be represent the corresponding corrections through which station B1, C1, D1 and E1 are required to be shifted as in Figure (a) for traverse to close. ABCDE will then represent the corrected closed traverse.