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Redevelopment Grauer Stein Tunnel

The Grauer Stein railway tunnel, which was built of blocks of Sandstone masonry in 1878, was completely revamped between 1998 and 2000 to make it safe for services. The structure had was in an extremely poor state owing to the dynamic strain caused by road traffic flowing over it (maximum overburden 20 m) quite apart from chemical attack by Seepage water and thawing salt. The tunnel was originally designed for twin-track operation but only one track was ever used from the very onset The tunnel's correspondingly large cross-section and the fact that the tunnel is only to be used for a single track in future made it possible to install a new reinforced concrete inner tube with an all-round seal in front of the old sandstone vault. The refurbishing operations had to be confined to nocturnal breaks in services and weekends without restricting daily rail services during the week so that the floor and vault were produced in 8 m blocks. The critical aspects of this scheme were the time pressure, co-ordinating the individual working stages taking the constraints imposed by rail services into account as well as the fact that material and equipment had to be brought to and removed from this line construction site by rail. Redevelopment measures:

  • renewing the tunnel by installing the floor and vault in blocks without restricting rail services during weekdays
  • consolidating the ground by grouting a filler suspension
  • installation of a statically completely effective tunnel tube in front of the old sandstone masonry
  • all-round waterproofing with 2 mm plastic sealing membranes
  • placing the floor in blocks using ancillary track bridges
  • placing the vault in blocks with steel formwork carriage
  • lengthening the tunnel by 20 m at both sides

Working conditions:

  • maintaining regular rail services during weekdays
  • work restricted to Monday to Friday from 8.30 p.m. to 5.00 a.m.
  • continuous weekend Operations from Friday 8.30 p.m. to Monday 5.00 a.m.
  • adhering to the clearance profile in every construction phase
  • application of track-bound construction equipment.
  • Country: Germany
  • Region: Rhineland Palatinate
  • Tunnel utilization: Traffic
  • Type of utilization: Main-line rail
  • Client: Deutsche Bahn AG
  • Consulting Engineer: BPI-Consult
  • Contractor: Hochtief Construction AG, Universale Bau GmbH
  • Main construction method: Refurbishment
  • Lining: Concrete formwork
  • No. of tubes: 1
  • Tunnel total length: 197 m prior to redevelopment, 237 m following redevelopment
  • Contract Volume: approx. € 5.5 million
  • Construction start/end: October 1998 to May 2000
  • Opening: 2000