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Real time structural health monitoring of railway tunnels (Rekawinkel, Austria)

Is our railway tunnel monitoring system capable of preventing concrete from falling onto the railway line?

Utilizing FBG technology, we implemented a unique real-time displacement monitoring of disturbed areas in rail tunnels. Upon exceeding predefined threshold levels, it promptly triggered alarm signals, instantly sending them to the client’s operations center.

  • Austrian railway company
  • displacement monitoring of disturbed areas in the concrete layer of the railway tunnel
  • automatic generation of alarms when thresholds are exceeded
  • necessity to keep railway operations undisturbed
  • ashlar masonry railway tunnels built in 1858
  • concrete layer flaking as a result of water penetration
WHAT did the client turn to us with

The railway tunnels in question are located on the ÖBB line Vienna – Linz. During their reconstruction in the last century, the vault was reinforced with concrete. Unfortunately, over the last decade, the concrete layer has started to flake as a result of water penetration and poor connection of concrete and sandstone masonry. As any loosened piece of concrete, which falls on the tracks, can be fatal for the fast passing trains, we were asked to implement the real time displacement monitoring of disturbed areas.

Benefits of the solution compared to conventional methods


Data is evaluated remotely, more than 2 km from the tunnel itself. After installing the sensors, you do not have to worry about interruptions in operation or track closures.

II. Immediate notification of a crisis

Threshold notifications are generated automatically and without delay.

III. Detailed overview of the technical condition of the tunnel

22 displacement tunnel sensors installed on the tunnel surface enable real-time, long-term monitoring of the lining condition.

How did we approach the solution?

We have developed the customized FBG displacement tunnel sensor, designed to monitor local structural deformations. Its smart transduction mechanism converts the displacement between the concrete layer and sandstone masonry to optical fiber elongation. This structural health monitoring sensor can, without any limitations, cope with the curved and rough surface of the tunnel and thus it efficiently operates even in harsh environments (e.g. water, EMI, or shock wave). In this project, we have combined 22 displacement tunnel sensors with 2 temperature sensors.

When there was no traffic on the line, we installed the FBGuard 1550 monitoring system, locating it 2 kilometers away from the last sensor. This 8 channel fiber optic interrogator was connected to the internet and available online for easy remote connection and system supervision.

All measured data were automatically streamed to the remote data server containing necessary instruments for subsequent data processing, management and visualization. Moreover, to ensure safe railway operation, the client’s civil engineers defined two alarm threshold levels that should not be exceeded, under any circumstances. When these levels were exceeded, indicating imminent flaking of the lining, the alarms were immediately generated and sent to the client’s operational center.

Gallery from realized project

Why work with us?

Our company was invited to the project thanks to its professional expertise and experience in providing fiber optic sensing systems for monitoring the structural health of engineering structures.

We work with fiber optic structural health monitoring sensors we manufacture to monitor the stability of buildings and infrastructure. The calculations are based on state-of-the-art numerical modeling approaches. Thanks to this, we always guarantee the reliability of our solutions.

FBG technology is the most suitable solution where conventional procedures fail or are not viable because of routine operation.

Our railway tunnel monitoring solutions can be modified to meet your project’s needs, such as the desired functionality, interoperability, etc.

Electrical sensors may stop working due to wear and tear or weathering. This causes additional costs. Fiber optic technology is characterized by high durability and reliability.

How can we help you?

Are you considering our products and solutions, need to consult about your project with us, or would you like to establish long-term cooperation with us? Contact us. We’ll do our best to answer any questions you might have within 24 hours.

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