 In order that the design of the scheme can be correctly fixed in position, it is necessary to establish points on the site which the E, N coordinates are known.
 These are horizontal control points and, once they have been located they can be used with a positioning technique to set out E, N coordinates of the design points.
 Two factors need to be taken into account when establishing horizontal control points.
1. The control points should be located throughout the site in order that all the design points can be fixed from at least two or three of them so that the work can be independently checked.
 The design points must be set out to the accuracy stated in the specifications
Vertical controls