- In engineering the production of an accurate large-scale plan is usually the first step in the planning
and design of a construction project.
- Thereafter the project, as designed on the plan, must be set out on the ground in the correct absolute and relative position and to its correct dimensions.
- Thus, surveys made in connection with a specific project should be planned with the setting-out process in mind and a system of three-dimensional control stations conveniently sited and adequate in number should be provided to facilitate easy, economical setting out.
- It is of prime importance that the establishment and referencing of survey control stations should
be carried out at such places and in such a manner that they will survive the construction processes.
- This entails careful choice of the locations of the control stations and their construction relative to their importance and long- or short-term requirements.
- For instance, those stations required for the total duration of the project may be established in concrete or masonry pillars with metal plates or bolts set in on which is punched the station position.
- Less durable are stout wooden pegs set in concrete or driven directly into the ground.
- A system of numbering the stations is essential, and frequently pegs are painted different colours to denote the particular functions for which they are to be used.