Robotic total stations (RTS) are frequently used for the measurement of temperature induced bridge deformations or during load testing of bridges. In experimental setups, total stations have also been used for the measurement of dynamic bridge deformations. However, with standard configurations the measurement rate is not constant and on average an update rate of 7–10Hz can be achieved. This is not sufficient for the vibration monitoring of bridges considering their natural frequencies which are also in the same range. In this paper, we present different approaches to overcome these problems. In the first two approaches we demonstrate how the measurement rate to prisms can be increased to 20Hz to determine vertical deformations of bridges. Critical aspects like the measurement resolution of the automated target tracking and the correct sequence of steering commands are discussed. In another approach we demonstrate how vertical bridge vibrations can be measured using an image assisted total station (IATS) and corresponding processing techniques. The advantage of image-based methods is that structural features of a bridge like bolts can be used as targets. Therefore, no expensive prisms have to be mounted and access to the bridge is not required. All approaches are verified by laboratory investigations and their suitability is proven in a field experiment on a 74m long footbridge. In this field experiment the natural frequencies derived from the total station measurements are compared to the results of accelerometer measurements.

Today, many civil engineering structures are permanently monitored to provide early warnings from structural failure. Many of the currently used measurement sensors have the drawback that access to the monitored structure is required. Furthermore, different types of instrumentation are needed to measure vibrations and displacements. We therefore propose the usage of an image assisted total station (IATS) for vibration- and displacement monitoring. Compared to previously reported approaches using IATS prototypes, our system is based on a commercially available standard IATS. In laboratory investigations, we show that the used IATS can measure displacements with a precision of 0.1 mgon. In a field experiment at a lifesize footbridge we compare the IATS measurements to currently used accelerometer and total station measurements.

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