New Busch Tunnel

The Busch Tunnel lies on the Cologne-Aachen-Brussels redevelopment route shortly before the Belgian border. The route is to be upgraded to create a faster connection to the metropolises of Brussels, Paris and London. The Busch Tunnel development scheme foresees the improvement of the line over an approx. 3.2 km long section between Aachen Central Station and the Belgian border. Subsequently, trains will be able to travel through the Busch Tunnel at speeds of up to 160 km/h. The construction of a new single-track tunnel and the refurbishing of the existing Busch Tunnel for single-track operation represent a major element of the redevelopment measures. Supporting structures in the form of drilled piling and sheet walls are to be installed in the deep pre-cuts and along the rest of the section. A slab track is to be laid from km 72.9 up to the end of the 2 tunnels. The changeover to Belgian left-hand traffic will take place at Aachen Central Station. The same applies to switching from the 15 kV 16 2/3 Hz power system to the Belgian 3 kV direct current system, which will continue to be done at Aachen Central. The New Busch Tunnel is to be driven at a gap of from roughly 25 to 45 m to the east of the Old Busch Tunnel. Roughly at its centre the tunnel passes beneath the B 264 a "Lütticher Straße" and shortly before the southwest portal, a row of houses with access roads. The pre-cuts have to be widened to roughly 34 m in order to drive the new tunnel. On account of the high, steep embankments, back-anchored drilled piling walls have to be installed up to a height of 20 m, in some cases in several layers. These walls are lined with structural shells. The tunnel is located in Hauset Sand whilst the Aachen Sand that is to be found underneath it, is also partially penetrated. The former largely consists of fine sands with cohesive intermittent layers of plastic clays. The Aachen Sand constitutes densely bedded fine grained quartz sands containing layers of sandstone, which are generally up to 50 cm thick and as much as 25 m thick in some places. The groundwater table is located roughly 15 m beneath the planned tunnel floor in Aachen Sand, although it can rise to slightly under this level. Beneath the groundwater table, the borehole floor frequently swells when the samples are recovered owing to under pressure and hydraulic gradients. The prevailing fine sands reveal a tendency to flow given high hydraulic gradients. The tunnel is to be driven from the northeast portal with a crown heading with secured crown floor. A short counter-drive is to be undertaken at the southern start-up wall. The tunnel is to be driven from both portals protected by an up to 17 m long pipe umbrella. For the drive in the prevailing fine sand, advance supporting of the crown will be carried out using grout lances given lengths of advance amounting to 1 m. Advance anchoring will be used to support the face and it will be necessary to retain a 45/50° supporting core. An anchoring system consisting of 4 to 6 m long soil nails is designed to strengthen the rock bearing ring around the tunnel. The face is to be secured by means of shotcrete immediately after the excavator drive and the 2-layer reinforced, 30 cm thick shotcrete outer shell installed. Ring closure in the floor will also take place for the crown drive. Once the crown is broken through, the bench and floor will be tackled in 2 and 4 m lengths of advance.

Country: Germany
Region: Aachen, North Rhine Westphalia
Tunnel utilization: Traffic
Type of utilization: Main-line rail
Client: DB Netz AG
Consulting Engineer: DB Projektbau GmbH, NL West
Construction Monitoring: Prof. Dr.-Ing. Bernhard Fröhlich, gbm
Examination: Dipl.-Ing. R. Maidl
Contractor: Hochtief Construction AG, Hartung Bau, Eichholz
Main construction method: cut-and-cover
Type of excavation: Excavator
Lining: Concrete formwork
No. of tubes: 1
Tunnel total length: 711 m
Cross-section: 104 m² excavation
Contract Volume: € 115 mill. for tunnel, € 25.0 mill. for total scheme
Construction start/end: June 2005 to September 2007