Straßentunnel Bonn-Bad Godesberg, Baulos T01

The tunnel largely passes through sandy and gravely layers of soil belonging to the Rhine Valley Niederterrassen. The lower third of the tunnel cross-section is located in groundwater. The tunnel passes below the district of Bad-Godesberg with buildings, some of which are up to 100 years old. The main DB line from Coblenz to Cologne is passed under twice and the tunnel also undercuts an existing urban railways tunnel. The two two-track tubes in a northern direction as well as the trilinear cross-section towards the south were tunnelled from the starting shaft at the same time using mining means. This cross-section is some 30 m wide in all. The tunnel excavation is divided up into advance crown/bench excavation and follow-up base excavation. Systematic advance supporting using high-pressure injections (Jet Grouting) in the crown and walls is applied. The length of the individual grouted sections amounts to 12 m. When the silt horizon dips into the roof zone, advance securing is carried out using round steel lances. The tunnel walls are secured with reinforced shotcrete, tunnel arches and temporary bench floor. From the level of this temporary floor, provisional groundwater lowering is carried out with well galleries for the final base excavation and until the concrete inner shell is created. Excavators are used to remove the soil, the overbreak and overlaps of the jet columns are tackled by a cutter on a telescopic excavator. On account of the sensitiveness of the buildings on the surface, 20 mm maximum surface Settlements are allowed. This condition places high demands on the coordination and the sequence of the various construction phases. Thus for example, in the trilinear southern section, the two outer tunnel tubes had to be completed in advance with a bearing inner shell so that these were in a position to act as abutment for the central tube, which had still to be driven with an excavated cross-section of up to 140 m². In the starting shaft as well as in a drainage facility with emergency exit, the tunnel is driven via cut-and-cover with watertight excavation and underwater concrete base.

• Country: Germany
• Region: Nordrhein-Westfalen
• Tunnel utilization: Traffic
• Type of utilization: Road tunnel
• Client: Stadt Bonn - Tiefbauamt
• Main construction method: Trenchless
• Type of excavation: Drill-and-blast/Excavator
• Lining: Shorcrete
• No. of tubes: 2
• Tunnel total length: 2200 m
• Cross-section: 80- 140 m²
• Contract Volume: 150 mill. DM
• Construction start/end: 1992 till 1996
• Opening: 1997