Bridges at Breaking Point: Stress Test for Germany’s Infrastructure
The numbers speak for themselves: about half of Germany’s 28,000 motorway bridges require refurbishment. This is primarily a result of the vast increase in strain by modern heavy-goods vehicles with up to 11 tons of axial load, with which the structures cannot cope. Old bridges and today’s traffic are simply no longer compatible. By Ruben Vorwald
The collapse of the Carola bridge in Dresden in September 2024 was a wake-up call: Germany’s infrastructure is getting on in years. Many roads and bridges which were built from the 1960s to the 1980s are no longer able to cope with today‘s traffic.
Old bridges, more and more traffic
One example of how critical things are is the partial closure of the A45 motorway since the end of 2021 due to the decaying Rahmede Valley bridge which had to be demolished in a controlled explosion in May 2024. Every day, around 25,000 vehicles are diverted, causing immense strain on the region. Many of the “aged” bridges are damaged beyond repair and have to be demolished, necessitating complex and costly new buildings.
The problem is clear: back then, construction materials were far less durable than they are today. The pre-stressed concrete bridges, which make up about 70 percent of Germany’s motorway bridges, are at particular risk due to stress-corrosion cracking. Cracks in the concrete favour water and road-salt ingress, which damages the embedded steel and can lead to collapse in extreme cases.
Intelligent sensor technology for preventive maintenance
To avoid such catastrophes, the Fraunhofer institute for Non-Destructive Testing (NDT) is working on an innovative monitoring system, using smart sensors which continuously measure the condition of the bridges. “We must switch from reactive to predictive or proactive maintenance management” says Professor Hans-Georg Herrmann from IZFP. The sensors record important data such as concrete thickness or corrosion in the steel, and report problems at an early stage.
In comparison to conventional visual inspections which take place every three years, the new sensors enable continuous condition monitoring. This means that structural changes are detected in real time before visible damage occurs. Energy-wise, the sensors are self-sufficient and could even be powered by solar cells, enabling non-stop monitoring.
More safety for trams, too
Innovative technology of this kind can also be applied in the tram sector. Railway tracks and flyovers which are often heavily used could also benefit from the intelligent sensors. Expensive repairs and unplanned service interruptions can be prevented if damage on tracks or bridges is detected.
HANNING & KAHL’s ConnAct® supports comprehensive monitoring and efficient maintenance of tram-traffic infrastructure. By continuous remote condition monitoring, diagnosis and control, ConnAct® optimises maintenance processes by demand-oriented control of inspections and early detection of possible weaknesses. This greatly enhances the safety of the equipment, minimises unplanned downtimes, and sustainably reduces operating costs.