Numerical transmission line models are an essential tool for the planning and dimensioning of high-voltage overhead lines. They allow a realistic estimation of the transmission line be-havior. This includes for example calculations of unbalance effects or currents in ground wires and towers. Based on a previously developed vector-based transmission line model [2], which explicitly considers the finite length of the ground wire and the propagation resistance of the grounding system of the towers, this paper presents a detailed experimental validation using a measurement of a real high-voltage overhead line. For this validation, a real transmission line is modeled in detail, which enables the calculation of the transmission line behavior and the tower currents flowing into the ground during opera-tion. For validation, the currents and voltages are measured time-synchronously at both ends of the line and are used as input variables and as reference values for the predicted cur-rents and voltages on the other side. Another synchronous measurement of the tower currents during operation allows further evaluation of the calculation accuracy of the line mod-el. The results show that the model is very accurate at signifi-cant load conditions. Deviations from the measurements in-crease at low load conditions, which is explained by simplified capacitive couplings in the model. Finally, approaches for improving the capacitive coupling models are proposed.