Noise anomalies, such as the impact of a vehicle against the tunnel wall, the sound of two vehicles crashing, squealing tires, the impact of lost cargo, etc., as well as anomalies in the sound of individual vehicles can be recognized by a advanced system to detect acoustic anomalies and tunnel-mounted microphones.
Incidents are detected acoustically via microphones installed in the tunnel. Abnormal sounds are recognized and an alarm is transmitted to the control room within 0.7 seconds. The operator can then decide whether to activate the tunnel traffic lights and other emergency measures.
Special detection algorithms make it possible to automatically identify sounds and assign them to specific alarm classes. One big advantage of acoustic detection methods is that accidents or critical incidents in tunnels are virtually always accompanied by a characteristic sound. These sounds occur concurrently with the incident and can thus be immediately detected. The detection of an incident allows measures to be immediately and automatically activated. Activation of the relevant camera is an example of such a measure.
The Acoustic Tunnel Monitoring gives also live monitoring of the sound in the tunnel, ring buffer and event log for all microphone signals, incident information even with poor visibility and opportunity to locate and start communication with persons in the tunnel during an incident.
The equipment installed in the harsh environment is a microphone that is resistant to dirt and corrosion and jet washing. This gives a quite easy system to maintain and clean in the tunnel.
The traffic control centres in Austria has given this system a good review after several tests, and the technology is now available from Joanneum Research (Austria). The federal highway agency ASFINAG will equip all 32 tunnels of danger class 3 and 4 with AKUT by 2019.
"Experience so far has shown that accidents were always recognized first by the acoustic tunnel monitoring system. The time gained was between just under one more than two minutes. In the event of an accident this time difference could save lives."
Says DI Gerhard Ruhdorfer, project manager at ASFINAG
We visited the Traffic Control Centre in Klagenfurt and we learned that ASFINAG and the Traffic Control Centre Officers were pleased about the system, and that the system was reliable and easy to maintain. The system impresses us, not at least because of the use of technology in such an innovative way. We will follow the development of this technology and find it particularly interesting that the solution provides "ears" to the tunnel.
The video is from the technical visit in Klagefurt.