Hybrid State Plane Coordinate System for Transforming a Citywide Survey Control Network to Surface Values: Case Study for Frisco, Texas

The city of Frisco, Tex., published state plane coordinates were “ground scaled” into surface coordinates for the purpose of establishing a hybrid coordinate system to be easily used by surveyors. Nineteen city monuments were found and collected by GPS observation using real-time kinematic (RTK) connected to the Texas RTK Cooperative Network. The network creates a virtual reference station near the GPS roving receiver, allowing the surveyor to use the rover unit by itself without the need for setting up a base station on the project site. Using a GPS manufacturer’s standard protocol, localizing ground-scaled GPS vectors to the city’s hybrid values yielded acceptable horizontal $\left(H\right)$ and vertical $\left(V\right)$ residuals over a $233{\mathrm{km}}^2$ network. Two out of 19 monuments observed explained maximum residual error ( $H=0.029\mathrm{m}$ , $V=0.082\mathrm{m}$ ) with no significant differences in the mean $\Delta N$ and $\Delta E$ between published grid, hybrid, and surface coordinates $(P=0.77)$ . This paper will illustrate and discuss the procedures and results of this project.