Select the INCORRECT obstacle in chaining in a chain survey.
The measurement of distances consists of chaining and making offsets. During measurements, it is practically impossible to set out all the chain lines in a straightforward method because of a variety of obstructions to chaining and ranging in the field. The difficulties can be overcome by running perpendicular and parallel lines or by running a few additional lines and measuring angles by some instrument. The scope of the chapter limits the solution of the problems involving only the essential equipment used in chain surveying. To find the best and rapid solution, the surveyor should have a good knowledge of geometric and trigonometric principles.
The obstacles may be divided into two classes.
Those which do not obstruct the ranging (view) like ponds, rivers, and fall in the category of obstacles to measurement.
The others are those which we cannot see across, i.e., both the chaining and ranging are obstructed, e.g., houses, stacks, etc., and are known as obstacles to alignment.
1. Obstacle to ranging but not chaining: Examples: Forest, hill
2. Obstacle to chaining but not ranging: Examples: Small pond, small bend in the river.
3. Obstacles to both chaining and ranging: Example: A big building
Note:- Plotting is on paper it is not the obstacle for chaining.