Implementation of GNSS Continuous Operating Reference Stations for Surveying and Geodetic Applications in South West Nigeria

Continuously Operating Reference Stations provide the real-time and post-processed differential GNSS corrections that underpin high-accuracy positioning for professional surveying, engineering, and geodynamic research applications. This study examines the implementation and performance of the CORS network in South West Nigeria, with reference to stations operated by the Office of the Surveyor General of the Federation and the Ogun and Oyo State GIS authorities. Baseline data quality assessment is conducted using multipath indicators, signal-to-noise ratios, cycle slip frequencies, and data availability statistics for twelve months of archival RINEX data. Network RTK accuracy tests are conducted at forty distributed checkpoints in Lagos, Ibadan, and Abeokuta using single-baseline and VRS correction modes. The positioning accuracy achievable using the existing network is evaluated for cadastral, topographic, and engineering survey applications against the prescribed tolerances of the relevant Nigerian standards. Results demonstrate that network RTK from the South West CORS configuration achieves sub-centimetre horizontal accuracy for eighty-two percent of tested configurations, satisfying cadastral requirements. However, inter-station baselines exceeding seventy kilometres in the network perimeter produce degraded accuracy requiring supplementary static post-processing. The study recommends specific network expansion stations to close identified coverage gaps and provides operational protocols for surveyors utilising the network. Keywords: CORS, GNSS, network RTK, South West Nigeria, geodetic positioning.