The 2.2 km long Kaisermühlen Tunnel on the A22 Donauufer motorway is the longest motorway tunnel in Vienna. With a daily traffic volume of about 120 000 vehicles (of which 11 % are heavy goods vehicles), it is the most heavily used road tunnel in Austria. After a construction phase of about two years opperator Asfinag has now nearly completed the general refurbishment of all safety equipment (lighting, ventilation and fire protection) of the tunnel. With the acoustic monitoring system AKUT and 188 video cameras, the tunnel now also has “ears” and “eyes”. After the trial operations of the new systems, the completion works started on 28 January and should be finished by April 2019. The Asfinag is investing about 40 million euros in the new operations and safety systems of the Kaisermühlen Tunnel.
The electronic alarm system AKUT – developed by Joanneum Research in collaboration with the Asfinag – detects hazards in the tunnel from noise anomalies and activates an alarm immediately. One example is a large fire in the Gleinalm Tunnel on 5 October 2018; AKUT already activated after a few seconds as the first safety system. With the Kaisermühlen Tunnel, AKUT has now been installed in 24 tunnels; and 32 further should follow until 2029.
For the AKUT system, monitoring stations with altogether 91 microphones and 91 cameras were installed in the Kaisermühlen Tunnel every 100 m. These detect untypical noises such as a collision, squealing tyres of human voices and activate an alarm; the nearest video camera then automatically switches to a view in the responsible traffic centre, where the significance of the incident is immediately noticed.
In the Kaisermühlen Tunnel, 1575 LED lamps ensure optimal safety; the LED technology provides 60 % better lighting than previously – with a lifetime of ten instead to two years and altogether constant electricity consumption. The new LEDs in combination with the new reflections in the tunnel considerably improve visibility.
In front of the portals of the Kaisermühlen Tunnel are six large fans, with another 34 fans inside the tunnel, which should extract smoke gases out of the tunnel at about 2 m/s in case of a fire. All escape stairs are equipped with positive pressure ventilation. G.B.