The Kaisermühlentunnel in Vienna consists of a 2.1 km long section of the A22 Donauufer freeway. At least three lanes run in each direction as well as breakdown lanes and several approaches and exits. Between 100,000 and 150,000 cars use the Kaisermühlentunnel on a daily basis. Problems on this important arterial road inevitably lead to traffic collapse in the Austrian capital. After almost 28 years of continuous operation, in June 2017 the operating company Asfinag initiated a large-scale refurbishment project for the Kaisermühlentunnel—a delicate topic for a traffic hub. Only individual lanes were thus closed, if at all, and especially at night when traffic density was low. “For us as lighting partners, this meant that we had to deliver precisely the right quantities of luminaires just in time to ensure smooth project progress," states Günther Weinlich, Project Manager at SITECO.

A tunnel with eyes and ears
What makes the "new" Kaisermühlentunnel so special is its sophisticated safety concept. A total of 188 video cameras and 91 microphones serve as the tunnel's eyes and ears. They respond to unusual processes and sounds—the banging of a car door, squeaking tires, a collision or voices. Sensors measure temperatures and air values. All information comes together in a central control station in the "AKUT" alarm system. Only 23 other tunnels currently have this emergency system which is capable of reducing alarm times by a good four minutes and immediately initiating emergency operation or even closure. In Vienna, the central BUS control communicates not only with ventilation, speed displays and such systems but also with the lighting. In the event of danger for example, the lighting is automatically raised to the highest level. "With the current safety features we can well say that the Kaisermühlentunnel is one of the safest in Europe," said a convinced Kurt Portschy, Division Manager at Asfinag.

Improved lighting level for greater safety
Around 1,600 TL 31 LED tunnel luminaires from SITECO were installed during the upgrading project. These replace the former lighting consisting of sodium vapor lamps (SON). "The new solution generates eight times the illuminance with roughly the same electricity costs," explained Weinlich. Possible savings potential was not the decisive factor, but rather improved brightness levels and maximum safety in the tunnel. In the past, special hazard zones such as portals and exits were marked by a change in light color. "That's no longer needed today. We have such high lighting levels throughout the tunnel that best visibility is everywhere," informed Weinlich. Best vision and best visual comfort, because the lighting in the Kaisermühlentunnel also helps to adapt the eye to the visibility conditions in the tunnel. Luminance cameras measure the brightness in front of the tunnel and regulate illuminance inside the tunnel accordingly—a further contribution to road safety.

Smooth processes thanks to a customer-specific solution
Asfinag invested 40 million euros in the two-year refurbishment. SITECO not only provided the new LED tunnel lighting, but also assisted the operator with planning and commissioning as well as with final documentation and staff training. In addition, an alternative mounting for the luminaires was developed especially for the Kaisermühlentunnel, saving installation time and complexity in the client's interest. Günther Weinlich: "In the Kaisermühlentunnel there was already a cable route on the ceiling. It made perfect sense to use this instead of adjacently placing new installation points." For this reason the installed tunnel luminaires were quickly equipped with a new mounting option—and also on time. The upgrading measures to the Kaisermühlentunnel were completed at the end of 2018. Only final system checks were carried out in the first quarter of 2019.