A robotic total station (RTS) [or robotic theodolite or theodolite positioning system (TPS)] was used for the first time to measure the deflections of a short-span bridge in response to passing trains. The RTS measurements aimed to a reflector which was set on one of the midspans of the historical Gorgopotamos Bridge in Greece permitted to identify the measurement noise (apparent displacements) up to ±1.3 mm when no trains were passing, and deflections with peaks of 2.5–6 mm during intervals when small or larger trains were passing. These results confirm previous experiments and indicate that, under certain conditions (mostly favorable atmospheric conditions), an RTS can be used for monitoring dynamic displacements of relatively stiff bridges, and as a useful tool for structural health monitoring.