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LobdeburgTunnel - BAB A4

Within the scope of the German Unity Transport Project No. 15 the A 4 federal motorway was expanded to six lanes at the Jena part-section within a length of 6.7 km. The forecast volume of traffic for 2015 amounts to 85,000 vehicles/ day. Growing noise emissions in the vicinity of the Jena-Lobeda residential area and other affected localities represented a central problem for aligning the route. On the basis of preliminary investigations it was established that there was no alternative to the present motorway route. In order to reduce the noise nuisance for local residents, active noise abatement measures were arrived at by lowering the motorway in the vicinity of Jena-Lobeda, setting up a noise protection encasement for the motorway over a distance of 600 m near the residential area, establishing noise protection walls over a distance of 2.2 km as well as a noise protection wall on the Saale Bridge were planned and executed. The motorway gradient was lowered by as much as 7.5 m compared with the existing autobahn between the Saale Bridge and the Jena-Lobeda junction. The masses of earth taken from this zone were then used to cover the encasement. Apart from reduced noise emission the green belt around the eleven-storey residential buildings was revamped and in this way better access was arrived at towards the southern part of the residential area and the Saaletal valley. Work on the encasement began in October 2004. The 600 m long encasement for the motorway consists of two separate semi-circular vaults, which are shaped as an open frame structure. The inner walls of the two tubes are set up on a common foundation. Each tunnel tube consists of 60 blocks each 10 m in length. They were produced using watertight concrete without a seal. At the centre of the structure a cross-passage with an escape link between both tubes and an evacuation tunnel at the tunnel's south tube were produced. The clear cross-sectional width for each tube amounts to 18.75 m. ln their final state 4 lanes per directional carriageway will pass through each tube. In the portal zone the upper cut-off section took the form of a vertically set lip as a circular arch shaped reinforced concrete disc, which is designed with a structured in situ concrete closure at its upper end. The portals were designed with regular, circular shaped layers of masonry. In the wall zone the tunnel mouth was enlarged by producing vertically running protrusions. After the south tube was commissioned in May 2007 traffic was switched on to the completed directional carriageway Eisenach-Dresden (4 + 0 traffic) in order to produce the north tube. The north tube was due to be opened in September 2009. Thanks to this sophisticated engineering structure, noise and fume nuisance once affecting the residents of Jena-Lobeda will be considerably reduced, the living environment for around 25,000 people enhanced and at the same time costs for disposing of the material excavated when lowering the motorway, which would otherwise been necessary, avoided.

 

  • Country: Germany
  • Region: Thuringia
  • Tunnel utilization: Traffic
  • Type of utilization: Road Tunnel
  • Client: Federal Republic of Germany, Free State of Thuringia
  • Consulting Engineer: Krebs und Kiefer, Beratende Ingenieure GmbH, Erfurt
  • Construction monitoring: Ingenieurgemeinschaft Setzpfandt GmbH & Co. KG, Weimar
  • Contractor: Hochtief Construction AG, Leipzig
  • Main construction method: Open
  • Type of excavation: Incubation
  • No. of tubes: 1
  • Tunnel total length: 600 m
  • Cross-section: 2 x 18.75 m (clear width), 4 lanes (per tunnel)
  • Contract Volume: 19 mill. Euro (roughwork), 8.2 mlll. Euro (furnishing)
  • Construction start/end: 60 months?
  • Opening: May 2007 (south tube), September 2009 (north tube)
  • Completion: May 2010 (total)