Question

In an area to be surveyed the line which covers entire area to be surveyed and has to be measured very accurately is

• A. Base line
• B. Off sets
• C. Check lines
• D. Tie lines

Hint:

The name says it all: the base line is the "base" or "foundation" of the entire survey.
Just like the foundation of a building, it must be established with the greatest care and accuracy.

Answer 1

The Correct Option is A

Step 1: Think about how a chain survey is actually built up.
A chain survey works by covering the area with a network of connected triangles. Before you can draw a single triangle accurately, you need one long, straight reference line running through the site from which every other triangle is constructed, much like the trunk of a tree that all the branches grow from.
Step 2: See why this particular line demands the highest accuracy.
Because every other measurement in the survey, every triangle, every offset, every detail, is ultimately calculated relative to this one line, any error in it gets carried forward and magnified throughout the whole plan. That is why surveyors take extra care, using a well tested chain or tape and repeated measurements, to fix its length as precisely as possible.
Step 3: Rule out the other named lines.
Offsets are short perpendicular measurements used only to pick up small details near a chain line, check lines are extra diagonals used afterward to verify the triangles, and tie lines connect points for the same verification purpose; none of these span or control the entire survey the way the base line does.
\[ \boxed{\text{Base line}} \]