Principle of Acoustic Monitoring

The operating noise inside a tunnel is characterized by a specific mix of engine, rolling and airflow noise produced by vehicles passing through. Microphones installed in the tunnel detect acoustic anomalies such as a vehicle-wall and vehicle-vehicle collisions, tyre bursts, voices and shouts, etc. AI-based acoustic detectors recognise the abnormal sounds in real-time and allocate them to predefined noise classes. Accidents and other critical incidents in the tunnel are always accompanied by distinguishable sounds. These sounds occur at the instant in time of the incident  - not after a delay -  and can be detected immediately.

The huge advantage of acoustic detection is that AKUT can react directly to the critical incident (e.g. accident noise after a collision). This means that AKUT can trigger an alarm in the traffic management centre just 1 second after the incident. Other safety systems usually recognize the consequences of an accident indirectly (e.g. slow drivers, queues, etc.) and hence require a longer amount of time to trigger an alarm.

Therefore acoustic detection of an incident allows measures to be immediately and automatically activated. For example, the system may trigger an alarm in the tunnel control room and display the video camera image of the affected section on a central screen giving the tunnel operator a real-time overview of the situation. This saves valuable time in providing first aid to people involved and in alerting drivers approaching the scene of the accident.


Detection of incidents within 1 second

Localisation of incidents by assignment to nearest microphone

Alarm in the tunnel control room with category, event and camera image

Detection and localization of people through their voices/shouts

Live streaming of sounds and voices from the tunnel

Ring buffer for all microphone signals

More than 2.200 microphones
are currently in tunnels
in 24/7 operation


Schematic Diagram

Microphones are installed in the tunnel at a maximum distance of 125 m. AKUT can be installed completely self-sufficiently or in combination with other safety systems. If e.g. a video system is installed, it is advantageous to install the microphones at the same locations as the video cameras, as costs for cables, optical fibers and the power supply can be saved.

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