TRAGIC NEGLECT: Morbi bridge collapse in Gujarat claimed 141 lives | Photo Credit: VIJAY SONEJI

In the early morning hours on September 11, 2024, a 100-m section of the Carola bridge, on the Elbe river in Dresden (Germany), fell into the water. Fortunately, there were no people on that section and no injuries were reported. The bridge, an important road and tram crossing, had shown signs of structural problems and was due for renovation; investigations later pointed to corrosion and material fatigue in the steel components as key factors for the failure.

The collapse disrupted traffic and river navigation, and led to a decision to demolish the remaining structure and plan for a replacement. But more importantly, the incident has since been cited as a wake-up call for improved monitoring and maintenance of ageing infrastructure the world over, especially in India — a country still grappling with the memories of the tragic collapse of the Morbi bridge in Gujarat on October 30, 2022, which caused 141 deaths.

The Fraunhofer Institute of Germany, which swung into action soon after the Dresden bridge collapse, has come out with the finding that monitoring infrastructure is not only simple and easy, but also quite cheap — all you need is the will to do it.

The problem statement before the institute ran like this: High precision, long service life, continuous load-bearing, temperature tolerant from minus 40 degrees Celsius to 120 degrees Celsius. Where will you find such a device?

The solution was hidden in plain sight. Of course, in automobiles, says Christoph Sohrmann, Group Manager at Fraunhofer Institute of Integrated Circuits (IIS). “We could try MEMS sensors, for example, which until now have only been used in vehicles or cellphones but can ‘hear’ breaks in the wires of pre-stressed concrete bridges,” he says in a Fraunhofer Institute press statement, adding, “We will soon be testing this principle on a real bridge.”

Cheaper option

The statement reasons that commercially available sensors for infrastructural monitoring are 10 to 100 times costlier than the repurposed vehicle sensor technology, since many elements such as hardware, production standards, cybersecurity and sensor self-monitoring can be leveraged directly from automotive applications.

Radar sensors developed for the automotive sector cannot be directly used for structural health monitoring (SHM) because they lack the resolution needed to detect small changes and early damage in large engineering structures. To address this, Fraunhofer researchers are developing new monitoring approaches using a combination of tactile sensors and non-contact radar measurements. These methods are being tested on a 45-m experimental bridge at TU Dresden’s real-world laboratory in Bautzen.

Unlike conventional frequency-based techniques, the phase-based interferometric radar analysis allows the researchers to detect even extremely small static displacements — down to millimetre or even sub-millimetre levels — as well as structural vibrations at frequencies above 1,000 Hz. This makes the technology suitable for monitoring structural conditions and early signs of damage.

The measurement campaigns are conducted in close collaboration with safety authorities and civil engineering offices to ensure that the data collected are both relevant and easy to interpret. Civil engineering expertise from TU Dresden played a key role in shaping the monitoring strategy.

In a follow-up project called RICARES, starting this month and funded by the Sächsische Aufbaubank, the team will focus on long-term monitoring of railway bridges, though the technology is also applicable to road bridges. The project will explore how many sensors can be synchronised and how radar performance can be improved using antennas, lenses, or reflectors.

The researchers emphasise that affordable sensors can enable large-scale infrastructure monitoring, helping authorities build long-term datasets that are crucial for identifying early structural damage and improving safety.

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Published on January 12, 2026