Bächlestollen Freiburg im Breisgau

Into the rock

The course of the Bächlestollen in the east of Freiburg runs underground in the direction of the Swabian Gate and there feeds into the characteristic small canals in the centre of Freiburg. An inspection revealed that over half of the 500-metre-long tunnel was in need of renovation. KREBS+KIEFER planned and was in charge of the renovation of the natural stone roof, which was to be completed in the short period of just six weeks.

During preparatory cleaning, using the ideal water pressure depending on conditions was crucial in order not to remove the substance of the roof but to get rid of loose material. A 126-metre-long fissure in the arch crown was injected on a trass basis with an injection paste that was suited in structural and physical terms with natural stone stonework. During the work in the tunnel, the primary focus was on the safety of the people working there. KREBS+ KIEFER supplied them with fresh air via mobile construction fans. Outside, a safety officer kept in touch in order to be able to call the emergency services if necessary.


  • § 43 of the HOAI [German Fee Regulations for Architects and Engineers]:
  • Outline planning
  • Implementation planning
  • Preparation of the tender
  • Involvement with the tender
  • Site management
  • Special services:
  • On-site supervision
  • Health and safety coordination