ASSESSMENT OF SUITABILITY OF UAV AND GNSS IN ROUTE SURVEY TOWARDS VERTICAL ALIGNMENT DESIGN FROM OLORUNDA JUNCTION TROUGH, BALOGUN VILLAGE TO OLORUNDA VILLAGE, OYO, OYO STATE

ABSTRACT This project assesses the suitability of integrating Unmanned Aerial Vehicle (UAV) photogrammetry and Global Navigation Satellite System (GNSS) technologies for route surveying and alignment design along the Balogun Village to Olorunda Village corridor in Oyo State, Nigeria. The study aims to evaluate the precision, efficiency, and practicality of both technologies in generating spatial data suitable for alignment design. Field data acquisition involved UAV-based aerial imaging using a DJI Enterprise Matrice 350 RTK drone and GNSS ground observations using a Unistrong G970ii Pro Differential GNSS receiver in Real-Time Kinematic (RTK) mode. A total of 854 aerial images were captured at a flight altitude of 50 meters with 70% forward and 60% side overlap, while 11 Ground Control Points (GCPs) were established at 500-meter intervals to ensure accurate georeferencing. Data processing was carried out using Pix4D Mapper, where UAV images were processed to generate orthomosaics, Digital Surface Models (DSM), and 3D point clouds. The GNSS data were processed and integrated with the UAV outputs in AutoCAD Civil 3D (2022) to produce the final route alignment, profiles, and cross-sections. The integration of both datasets ensured consistency in horizontal and vertical positioning, with Root Mean Square Error (RMSE) values of 0.1111 m (Easting), 0.1273 m (Northing), and 0.5128 m (Height), confirming high positional accuracy. The study concludes that combining UAV and GNSS technologies significantly enhances the accuracy and efficiency of route alignment design compared to traditional surveying methods. The use of Pix4D Mapper proved highly effective in automating image processing and terrain modeling, demonstrating the feasibility of modern geospatial technologies for road infrastructure planning in developing regions like Nigeria.