Geodetic Control Network Densification for Engineering Projects in Plateau State

A reliable geodetic control network is the spatial backbone of engineering surveying, boundary demarcation, and infrastructure mapping. This study examines the densification of the existing geodetic control network in Plateau State to support large-scale engineering projects, particularly road construction and dam rehabilitation activities in the North Central zone. Existing primary and secondary control points from the Office of the Surveyor General of the Federation are retrieved and assessed for spatial distribution, integrity, and currency. Using differential GNSS observations conducted over a four-week field campaign, seventeen new tertiary control points are established across underserved sections of the state, with baseline processing performed using GNSS solutions software and constrained least squares adjustment. Positional accuracy of the new control points is verified against published primary control coordinates, yielding horizontal accuracies better than two centimetres. The study identifies significant gaps in the existing network, particularly across the southern districts of Shendam and Quan Pan, where no recoverable control monuments are found within a fifty-kilometre radius. Recommendations are made for the regular inspection, rehabilitation, and expansion of control infrastructure in line with the Survey Co-ordination Regulations. The study contributes to the practical knowledge of geodetic network design among undergraduate surveyors and highlights the need for sustained government investment in national spatial infrastructure. Keywords: geodetic control, GNSS, network densification, Plateau State, least squares adjustment.