Detecting bridge damage via airborne noise - research project

The structural monitoring of bridges is complex, expensive and labor-intensive. This is where a new research project from Thuringia comes in. Scientists at the Fraunhofer Institute for Digital Media Technology IDMT in Ilmenau are currently researching how bridge damage can be detected at an early stage in the future. The aim is an intelligent early warning system that detects the smallest changes in the material structure - even before visible damage occurs, said Olivia Treuheit, project manager at the Fraunhofer IDMT.

"We don't want to wait until it's too late to check bridges," said Treuheit. With the help of artificial intelligence (AI) and acoustic sensors, changes to bridge structures such as wear, cracking or loosening are to be detected. While previous acoustic emission methods make damage audible through absorbed vibrations, the Ilmenau team is focusing on airborne noise. These acoustically perceptible signals are generated when vehicles drive over the transitions. Treuheit explained that the AI filters out the ambient and background noise from the recorded audio files.

Hearing damage before it becomes visible

The Ilmenau scientists are working with the engineering firm Marx Krontal Partner (MKP/Hanover) on the project, which will run until the summer of next year. The Federal Highway Research Institute is funding the project with a quarter of a million euros. According to Treuheit, initial field tests will be followed this summer by a first major measurement on two bridges in Saxony - the Wesenitz and Sachsen bridges in Pirna. This test will provide an initial larger data set that can be analyzed.

The long-term goal is to develop a universally applicable prototype. "In a few years' time, we could have a small box that can be installed in any bridge structure and signal any damage that occurs," says Treuheit. Digital, reliable monitoring would make it possible to carry out repairs in good time, which could avoid long-term closures and cost-intensive renovations or even demolitions. It would also allow repair work to be planned in a more targeted manner - for example at times when there is less traffic.

The partial collapse of Dresden's Carola Bridge in September last year reignited the debate about the safety of buildings in Germany. Bridge closures and demolitions continue to make headlines, such as the closure of the Rahmede viaduct near Lüdenscheid due to irreparable damage to the supporting structure or the demolition of the badly damaged Ring Bridge in Magdeburg.