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Light Railway Cologne, construction section Mülheim, Lot M 1

The Mülheim construction section consists of 4 contract lots, the lot M 1 embraces the section from the Wiener Platz station to the stop at Herler Straße. The tunnel tubes were driven in Rhine Valley quaternary sands and gravels and run, in some cases, 50%, elsewhere completely in groundwater. The tunnel tubes were driven with a Herrnknecht GmbH hydro-shield. The shield was fitted with a 5-arm cutting wheel, with hydraulically extensible over-cutters attached to three of the arms. A crusher in front of the intake ports was capable of dealing with stones with an edge length of up to 50 cm. ln order to make the machine more manoeuvrable, the cutting wheel could be advanced by up to 350 mm. For particularly intensive steering corrections, it was possible to set one of the over-cutters at eccentric contour or light eccentric over-cut. This technique made it possible for the machine to drive radii considerably below 250 m. The tunnel tubes were built watertight in monocoque construction with reinforced concrete segments with all-round seals. The 1.2 m wide, 8-segment rings are coupled together with a groove and tongue system straight, right and left conical rings with a temporary helical connection were installed. However, for future applications, the ring design must be modified for the tongue and groove system turned out to be susceptible, as flaking on the outer side jeopardise the tightness of the tunnel. The efficacy of the seal in the zone endangered by flaking must be tested. The shield drive began in an access shaft at the ramp and led to the stop at Mülheim Station, which at the time had been completed in its raw state. The TBM was relocated on air-cushions on a travel way comprising steel plates and membrane. At the Wiener Platz stop, the TBM was separated from its back-up, turned and subsequently drove the second tube. The entire installation's availability amounted to 65 % on average, the mean rates of advance attained of 14 m/d were considerably higher than the projected 8 m/d (peak value 32 m/d). The intended construction time for the tunnels could be reduced from 23 to 13 months.


  • Country: Germany
  • Region: Nordrhein-Westfalen
  • Tunnel utilization: Traffic
  • Type of utilization: Underground, urban and rapid transit
  • Client: City of Cologne
  • Consulting Engineer: Zerna, Schulz & Partner, Pirlet & Partner, Ingenieurgesellschaft Maidl, Erdbaulaboratorium Essen
  • Contractor: Philipp Holzmann AG, Bilfinger + Berger Bau AG, Dyckerhoff & Widmann AG, Hochtief AG, Strabag Bau AG, Wayss & Freytag AG, Wiemer & Trachte
  • Main construction method: Trenchless
  • Type of excavation: Shield machine (SM)
  • Lining: Reinforced concrete segments
  • No. of tubes: 2
  • Tunnel total length: 2 x 1,240 m
  • Cross-section: Inner diameter 5.72 m; Outer diameter 6.56 m
  • Contract Volume: appr. 280 mill. DM
  • Construction start/end: 56 months, including 13 months for the shield drive
  • Opening: Raw construction: end of 1995