The new tube (east tube) of the Karawanken tunnel will be equipped with half ventilation. There is an exhaust air duct above the roadway, which is connected to the service buildings at the two tunnel portals. The service buildings (BZ1 and BS4) will each be equipped with an axial exhaust fan. In addition, jet fans will be installed in the tunnel tube, distributed along the length of the tunnel. Reversible jet fans with symmetrically profiled blades will be used. The fans are installed in the emergency access bays, taking into account the clearance of the tunnel. For overpressure in the emergency cross passages, 2 overpressure fans per cross passage are used.
The system concept is shown in the following figure.