The resilience of the built environment to extreme weather events is fundamental for the day-today operation of our transport network, with scour representing one of the biggest threats to bridges built over flowing water. Condition monitoring of the bridge using a structural health monitoring system enhances resilience by reducing the time needed to return the bridge to normal use by providing timely information on structural condition and safety. The work presented in this report discusses use of rotational measurements in structural health monitoring. Traditionally tiltmeters (which can be a form of DC accelerometer) are used to measure rotation but are known to be affected by dynamic movements, while gyroscopes react quickly to dynamic motion but drift over time. This review will introduce gyroscopes as a complementary sensor for accelerometer rotational measurements and use sensor fusion techniques to combine the measurements from both sensors to get an optimised rotational result. This method was trialled on a laboratory scaled model, before the system was installed on an in-service single-span skewed railway bridge. The rotational measurements were compared against rotation measurements obtained using a vision-based measurement system to confirm the validity of the results. An introduction to gyroscopes, field test measurement results with the sensors and their correlation with the vision-based measurement results are presented in this article.

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Structural health monitoring is a useful tool for evaluating the condition of bridges, with permanent systems installed on bridges which form vital links on the major transport network. The economic cost of the monitoring systems limits their installation on smaller bridges which make up the wider transport network. A short-term monitoring system can be quickly installed and adjusted to suit the requirements of individual bridges. These systems are ideal for rural regions with a high number of single span bridges on isolated road and rail networks. This report will review a single span bridge on a private heritage railway under loading from passing steam engines, including the Flying Scotsman. Acceleration data are used to determine the rotations and deflections of the bridge deck. To verify the data, deflection measurements at mid-span were recorded using a video-based measurement system. The deflection measurements from the accelerometers correlate with the video imagery measurements.