Survey control is a set of reference points with known positions or elevations used to locate and measure other features.
Definition
Survey control provides reference points that surveyors and project teams use to locate, measure, and coordinate site features. Control may be established for one assignment or tied to a specified coordinate system and datum. The surveyor documents its basis, accuracy, methods, and limits so design, construction layout, and later surveys can use it consistently. A firm's scope may include establishing points, verifying existing control, or delivering control data, depending on the contract. Points can be disturbed, inaccessible, or unsuitable for a later task, so users need to confirm their status and intended use. Survey control is not the same as a coordinate system or datum: control points carry project reference values, while the system and datum define how those values are expressed. The ASCE provides resources for civil engineering professionals.
How owners use it
- Owners confirm which party establishes, verifies, and preserves control points in the survey and construction scopes.
- Project managers document control references in plans and survey deliverables shared across disciplines.
- A project uses 4 control points, and 1 is found disturbed; 4 - 1 = 3 points remain for verification.
- Teams check control status before relying on earlier survey data for new layout or design work.
