Tunnel monitoring

Fiber optic tunnel monitoring – continuous tunnel monitoring

Fiber optic tunnel monitoring enables continuous condition monitoring of road, railway, utility, and infrastructure tunnels. An optical fiber installed along the structure serves as a distributed sensor and can detect structural and thermal changes over long distances.

Depending on the measurement method , strain, temperature, vibrations, and dynamic loads can be monitored and spatially localized. The technology is suitable for permanent installations as well as for temporary measurements during construction and renovation work.

Tunnel monitoring with fiber optic sensors

In distributed fiber optic measurement technology, the optical fiber itself becomes the sensor over long distances. This allows long tunnel sections to be monitored with high spatial coverage and unusual changes along the measurement path to be located.

Typical applications

• Road tunnel

• Railway and subway tunnels

• Supply and energy tunnel

• Water and wastewater tunnels

• Tunnel portals and cross passages

• Existing and renovated tunnels

• Construction and renovation measures
  
  

Measurable quantities

Strain and deformation: Mechanical changes such as strains, settlements or movements of the tunnel structure can be recorded and documented.

Temperature: Temperature distributions are continuously measured over long distances and local deviations can be spatially assigned.

Vibrations: Vibrations caused by road and rail traffic, construction machinery, blasting or other mechanical impacts can be detected.

Dynamic loads: Short-term and recurring loads can be recorded and compared over longer periods.

Advantages of fiber optic tunnel monitoring

• continuous monitoring of long tunnel sections

• high spatial measurement coverage

• precise localization of conspicuous areas

• large measuring distances

• passive sensor fiber without power supply along the measuring path

• insensitive to electromagnetic interference

• suitable for hard-to-reach areas

• temporary and permanent installation

• Long-term recording and trend analysis

• Integration into monitoring and control systems
  
  

Road and railway tunnels

In road tunnels, structural changes, temperature profiles, and loads can be monitored over the long term. Especially in older or unusual structures, continuous monitoring provides additional information between regular inspections.

In railway and subway tunnels, vibrations and dynamic loads caused by train traffic can also be recorded.

Tunnel monitoring during construction work

Temporary measurements are suitable for, among other things:

• Tunnel construction and renovation

• Drilling and civil engineering works

• Work on adjacent buildings

• Blasting work

• Track and road construction work

This allows changes to be continuously documented during a defined project period.

Permanent tunnel monitoring

For long-term monitoring tasks, the sensors can be permanently installed. Measurement data is continuously recorded, stored, and analyzed. In the event of defined anomalies or exceedances of limit values, automated alerts can be triggered and sent to a centralized tunnel monitoring system .