Underground Mining Traffic tunnel construction
The Farchant tunnel is part of the new B2 from Eschenlohe - Garmisch Partenkirchen, and serves as a bypass around Farchant. It was opened in May 2000, is about 2.4 km long and consists of two tunnels with two lanes each. The two tunnel tubes are connected by three cross-tunnels, two of which are for pedestrians and one for vehicles. These are found at intervals of approximately 600 m. The structure is aligned with the direction of travel of the traffic: the eastern tube leads to Munich and the western tube to Garmisch-Partenkirchen. The average daily traffic volume for the year 2009 was 26,475 vehicles per 24 hours.
The Farchant tunnel is equipped with operational buildings close to the portals; in addition, an operations centre with an exhaust air shaft is located in the middle of the tunnel. The 2006 edition of RABT requires the construction of emergency exits at regular intervals of 300 m in tunnels of 400 m in length or more. The existing interval between escape routes was thus too great. Moreover, connecting buildings between parallel tubes needed to be fitted with doors where they give out onto the vehicle tunnels.
To meet the requirements of RABT 2006 and bring the existing Farchant tunnel up to the currently required safety level, the following construction measures were necessary:
the construction of four additional pedestrian cross-passages between the tubes of the existing road tunnels; the four new passages are to be constructed using arched profiles, as in mines, the clearance must be 2.25 x 2.25 m.
Retrofit of the three existing cross-passages with smoke partitions and doors. Disabled-accessible redesign of the existing emergency walkways and emergency breakdown bays in front of the emergency cabins.
Passive safety facilities in the emergency breakdown bays (this requires the relocation of emergency cabins within the breakdown bays)
Closure of the slotted gutters; replacement of the existing cable shaft manhole covers (approx. 430 pcs.) in front of the emergency phone recesses throughout the entire existing tunnel and the existing cross-passages.
Coating of the entire tunnel soffits up to a height of 3 m (for reasons of historical monument protection and improvement of the lighting level).
Modification of ventilation for the event of fires.