Cologne North-South Urban Light Railway, Special Structures

Structure Bechergasse The interconnection section Bechergasse is the northernmost structure in contract section South. Here the two tracks coming from the Rathaus Station fork becoming four tracks which branch off towards the Breslauer Platz and Dom/ Hauptbahnhof stops. As a result a connection has to be established between the tunnel tubes over a distance of some 90 m. On account of the location of the structure beneath the groundwater level it is necessary to secure it against ingressing groundwater. To produce the structure, buildings were secured in advance on the western side of the Bechergasse and in front of the eastern side of the road, which at the same time serves to prevent ingressing groundwater penetrating the underground construction site. A triple overcut bore piling wall in the south eastern sector was created from the surface as was the jet grouting zone for the southern pressure seal. The other supporting measures such as the interceptor plate above the northern half of the structure and the pipe umbrellas and compensation bores were created from the two excavation pits in the Bechergasse or in front of the Hotel Residence. Following up on these advance measures both tunnel tubes were driven from the south; the machines were recovered at Kurt-Hackenberg-Platz and removed. Also from the Kurt-Hackenberg-Platz construction site large freezing lances were drilled beneath the base of the subsequent structure; which extent into the southern jet grouting pressure seal. Parallel to this, stabilising parts of the subsequent structure were produced in the tubes- inner shell C-sections made of in situ concrete. By freezing the ice zone a temporary closed trough was created underground, which does not allow groundwater to enter. The southern diaphragm wall in the Kurt-Hackenberg-Platz excavation pit was opened up between the tubes and the outer contour of the interconnecting structure excavated in a number of part-drives. The excavated cross-section was secured immediately behind the drive through the soil. Subsequently the segmental pipes now visible at the side were cut open. In the cavity thus created the C-sections at the west and east side were linked with the interconnect ion structure by means of a conventional in situ concrete construction. Waidmarkt Track Change On March 3rd, 2009 huge quantities of subsoil fell into the Waidmarkt special structure. As a result of this the City of Cologne's Historic Archives collapsed and two people lost their lives. So far the cause (or causes) of the disaster is still unknown. Owing to all that happened a scheme for redevelopment and in turn the effect on the date for opening services still remain to be resolved. It is assumed that the 1st construction stage will possibly not be opened until 2013.

Country: Germany
Region: North Rhine Westphalia
Tunnel utilization: Traffic
Type of utilization: Underground, urban and rapid transit
Client: Kölner Verkehrs-Betriebe AG
Project Engineers/Construction Management: Ingenieurgemeinschaft PNS • Schüßler-Plan • Obermeyer
Consulting Engineer: Zerna Ingenieure GmbH, Schüßler-Plan, Pirlet & Partner Baukonstruktionen Ingenieurgesellschaft mbH, PSP Beratende Ingenieure, Jessberger, Iproplan
Roughwork Supervision: Kölner Verkehrs-Betriebe AG, Ingenieurgemeinschaft IBS • Zerna Ingenieure fürTunnelbau, Grund- und Ingenieurbau • Erdbaulaboratorium Essen {ELE)
Contractor: Section North: • Hochtief Construction AG • Keller Grundbau GmbH • Brückner Grundbau GmbH • Bauer Spezialtiefbau GmbH Section South: • Bilfinger Berger AG • Wayss & Freytag AG • Ed. Züblin AG
Main construction method: Trenchless
Type of excavation: Excavator
Tunnel total length: 90 m + 50 m
Construction start/end: 2005 -