Bayreuth Encasement - A 9

The Bayreuth Encasement is a road tunnel on the A 9 federal motorway and is located between the Bayreuth Nord and Bayreuth Süd junctions. The structure was produced in conjunction with the six-lane development of the A 9 (German Unity Transport Project No. 12). The original planning foresaw the construction of high noise protection walls at this point on the A 9. Ultimately the encasement solution was introduced at the behest of residents and local politicians and on account of the residential buildings established in the area. An urban road as well as the Bayreuth-Warmensteinach rail line runs above the encasement. The encasement comprises a two-cell framework structure. The east tunnel tube is 360 m long, whereas the west one, on account of the proximity of the Bayreuth Nord junction, is only 310 m long. At its central area the encasement is covered over with up to 1.50 m of earth. The two tunnel tubes possess clear widths of 17 m (east) and 18.75 m (west). Both tubes have three vehicle lanes and a 2.50 m wide hard shoulder. The carriageway is 14.30 m wide. The west tube also contains the slip lane for the Bayreuth Nord exit. The emergency pathways are 1.00 m (at the side) and 1.25 m (central strip) wide in the east tube whereas they all possess a width of 1.50 m in the west one. The encasement's walls are set up directly on bored piling with a diameter of 1.20 m. The outer walls are 0.85 m thick, the centre wall 1.00 m. The thickness of the ceiling varies between 0.95 and 1.05 m. The piles, walls and ceiling are rigidly connected with each other. The walls and ceilings are produced from B 35 watertight concrete. Construction forged ahead without unduly interrupting the flow of traffic on the nearby motorway. While one tube was being built traffic was diverted over the neighbouring directional carriageway. In order to reduce noise emissions high absorbing elements were introduced into the tunnel at each portal over a length of 60 m. The bridge over the Roter Main is located at the south portal. It possesses a special bearing structure with glazing for noise protection, which connects directly with the tunnel portal. For noise protection reasons the porous, low-noise drainage asphalt, which was used for the open road, was also installed over the first 20 m of the encasement. A 3 cm thick covering layer of mastic asphalt with the addition of brightening stone has been installed in the other sections of the tunnel tubes in order to improve the visibility. Emergency exits leading to the other tube as well as to the surface are set up in both tubes. The operating technology for the encasement is in keeping with RABT 2006 standards. Initially mechanical ventilation is not required. The lighting system is geared to operating in accordance with a permissible peak speed of 100 km/h. Connect ions for mobile power units back up the stationary energy supply. All data are transferred to the Nordbayern traffic control centre at Fischbach near Nuremberg. There all operating systems for the Autobahndirektion Nordbayern are monitored without Interruption 24 h/day.

Country: Germany
Region: Bavaria/North Bavaria
Tunnel utilization: Traffic
Type of utilization: Road Tunnel
Client: Federal Republic of Germany, Free State of Bavaria
Consulting Engineer: Autobahn Direktion Nordbayern/Köhler+ Seitz, Munich/Emch + Berger, Nuremberg/Gackstatter Beratende Ingenieure, Erfurt
Contractor: JV Riebel/Leitenmaier, Mindelheim; OSMO-Anlagenbau, Georgsmarienhütte
Main construction method: Open
Type of excavation: -(Encasement)
No. of tubes: 1
Tunnel total length: 360 m (east tube), 310 m (west tube)
Cross-section: 310 m² (in open construction pit)
Contract Volume: 14 mill. Euro (structure), 3 mill. Euro (operating technology)
Construction start/end: 2004-2006 (34 months)
Opening: October 2006