Survey Stations is a point of importance at the beginning and end of chain line. There are two types of survey stations:
- These are the end of survey line i.e. which connects boundaries.
- Line joining Main Stations is called Main Survey Line or Chain Line.
- They are represented by Circle, Capital letters A B... Or number 1 2... Or (A)
Subsidiary or Tie Station
- These are the points selected on main line, where it is necessary to run auxiliary lines to locate interior details such as corner, tree, building etc.
- Lines joining tie station are called Tie Lines or Subsidiary Lines
- They are represented by Small letters a, b,
Selection of Survey Station
The following points should be kept in mind while selecting a station:
- The stations should be mutually inter-visible
- Main principle of chain survey should strictly be observed
- If possible, line through the whole length of area should be drawn
- All triangles should be well defined
- A check line should be provided in each triangle
- Survey lines should be as few as possible
- A number of tie lines should be drawn
- Position of survey lines should be such that to avoid obstacles to chaining and ranging
- It should be on level ground
- The sides of triangle should pass as close to the boundary as possible.
- Base line
- Check line
- Tie line
Also See: Types of Surveying Chains
- The longest of the chain lines used in making a survey is generally regarded as Base line.
- It is the most important line because it fixes up the direction of all other lines, since on base line, is built framework of a survey.
- It should be laid on level ground, as possible through the center and length of the area.
- It should be correctly measured and should be measured twice or thrice.
- A check line also called proof line is a line joining the apex of a triangle to some fixed point on the opposite side.
- A check line is measured to check the accuracy of the framework.
- Thus there is a complete check on the field measurement as well as on the accuracy of the plotting work.
- A tie line is a line joining fixed points termed as Tie station on the main survey lines.
- A tie line usually fulfill a dual purpose i.e. it checks the accuracy of the framework and enables the surveyor to locate the interior details which are far away from the main chain line
Let us know in the comments what you think about the concepts in this article!