At just 6.5 kilometres long, this bus route is nevertheless demanding. Up to 3700 passengers per day travel Germany's steepest bus route on the 1834-metre high Kehlstein Mountain where the Eagle's Nest is located. In the Berchtesgaden Alps, gradients of up to 24 percent test both driver and vehicle. During the second week of May, the regional bus company Regionalverkehr Oberbayern GmbH (RVO) added three new Mercedes-Benz Citaro Euro VI models to its fleet of intercity regular-service buses on the Kehlstein route. To mark the commissioning of the vehicles Tammo Voigt, Head of Public Transport Fleet Sales within the Mercedes-Benz Bus and Coach unit, symbolically handed over the key to Mr. Nicolaj Eberlein, division manager transportation/marketing (RVO).
A few statistics indicate the challenges awaiting the new Citaro buses: The high mountain road is on average just 3.5 m wide and has an elevation change of 770 m from its lowest to highest points. Vehicles go through five tunnels (total length 273 m). The route is seasonal with operation typically commencing in mid to late May and ceasing in late October. Extreme weather conditions need to be anticipated at all times, as well as bad roads. At peak times, up to 14 buses are in simultaneous use. There is only one passing place on the entire route: whilst vehicles travelling down towards the valley stop and wait for those going uphill to pass, passengers are able to enjoy a view of the Königsee.
RVO specially configured their new vehicles to complete the uphill stretches briskly and the downhill sections as safely as possible. Complying with the Euro VI standard, the Mercedes-Benz OM 936 engine delivers a torquey output of 260 kW (354 hp). Maximum torque of 1400 Nm is reached as early as 1200 rpm and the four-speed automatic transmission is precisely tailored to the Kehlstein route. The overall gear ratio of 6.21 means that the lower gears take into account the route's specific topographical features and retarder performance is significantly boosted on descents.
Painted in traffic red, the Citaro Ü models also cope with the high number of passengers. Two electric pivot-and-slide doors ensure the flow of passengers is smooth at stops. There is also space inside for seats and a wheelchair area. All passengers must be seated before the driver negotiates the steep mountain road. Separate roof-mounted air-conditioning systems ensure that the passenger compartment and driver's station are the right temperature.
The Kehlstein route has been operated by RVO (DB Bahn Oberbayernbus) since 1 June 1976 on behalf of the Berchtesgaden-Königssee tourism region (TRBK). Operations are managed using a sophisticated system, thereby allowing some 300,000 visitors each year to use Germany's highest bus route. The journey time to ascend the Kehlstein is only about 15 minutes.