Assessing the Accuracy of a Network of GPS Passive Stations in Duhok City

Authors
Farsat Heeto Abdulrahman 1
Sarhat M. Adam 2
Yousif Y. Zaia
1 Department of Civil Engineering, University of Zakho, Zakho 42002, Kurdistan Region, Iraq.
2 Department of Civil Engineering, University of Duhok, Duhok 42001, Kurdistan Region, Iraq.
10.24271/psr.2026.244510
Abstract
Surveying plays a critical role in engineering projects, particularly in obtaining precise positional data for construction areas. For this purpose, accurate Reference Control Points (RCPs) are essential. RCPs can be either permanent (constructed with concrete or other materials) or temporary (used for local projects and established using GNSS positioning principles). Although temporary RCPs can be accurately determined from GNSS data through statistical analyses, their reliability tends to degrade over time. In 2011, a German company (Vossing) established a network of RCPs to support the Duhok city master plan. These RCPs have since been widely used by surveyors and engineers; however, their positional accuracy has never been systematically evaluated. This study presents the first comprehensive assessment and refinement of the Duhok RCP network using modern GNSS online processing platforms OPUS, AUSPOS, and CSRS-PPP. The RCPs were re-measured, processed, and statistically analysed to determine positional shifts and uncertainties relative to their original coordinates. Results illustrated that the mean uncertainties of approximately 27 cm in the East, 37 cm in the North, and 2.5 cm in height, corresponding to a total shift of about 46 cm with an azimuth deviation of 53° 34′ 37.709″. The findings demonstrate that long-term reliance on outdated RCP coordinates can introduce significant positional errors. This research not only quantifies the current accuracy of the Duhok network but also introduces a replicable methodology for verifying and updating control networks in regions lacking continuous GNSS reference infrastructure.
Keywords
"> Manuscripts
Accuracy of GCPs, Shift, Online services, analysis, Evaluation
Crossmark
Subjects
Passer Journal of Basic and Applied Sciences
Volume 8, Special Issue
Proceedings of the 5th International Conference on Advanced science & Engineering ICOASE 2026, University of Zakho and Duhok Polytechnique University, 00th – 00th September 2026
August 2026
Pages 214-227