In project control surveys, what orders of control are typically used?

• A. Primary (Third Order), Secondary (Fourth Order), and Tertiary Control
• B. Primary (First Order) and Secondary (Second Order)
• C. Tertiary Control Only
• D. All Orders Up to High Order

Answer: (A)

Project control surveys rely on a hierarchical network where a stable, wide-area frame is built first and then progressively denser, more detailed networks are connected to it. The typical setup uses primary control at the Third Order, secondary control at the Fourth Order, and tertiary control at the Fifth Order. This combination provides a solid global reference (primary) while giving enough local accuracy through secondary points and practical, construction-ready accuracy through tertiary points. It balances accuracy and cost, ensuring the project can be properly oriented and coordinated without overspending on the highest-order measurements.

Using first- and second-order control would imply much higher precision than usually needed for project control surveys, making it unnecessarily expensive. Relying only on tertiary control would miss the essential large-scale tie-in and orientation that come from a higher-order frame. Including all orders up to high order would be more than what’s typical for project work.