A Survey Station is a point of Importance at the beginning and end of a chain line. There are two main types of stations namely Main station and Subsidiary or Tie station.
Main stations are the ends of the lines which command the Boundary of the survey, and the lines joining the main stations are called main Survey or Chain lines.
Subsidiary or tie station
Any Point selected on the main survey line where it is necessary to run the auxiliary lines to locate the interior details such as fences, hedges, buildings,etc., when they are at some distance from the main survey lines are known as Subsidiary or Tie stations .
The lines joining such stations are known as tie line or subsidiary line.