B 31 Stadttunnel Freiburg

Service period:
2011 – 2022

Project client:
State of Baden-Württemberg represented by Freiburg Regional Council

Project volume:
€ 325,000,000

Project description

Over recent years successive widenings of the B 31 to 3 or 4 lanes have been carried out to increase its capacity. The two remaining bottlenecks in Falkensteig and in Freiburg considerably restrict traffic flows on the trunk road and are responsible for severely detrimental environmental effects on the adjacent settlements and their inhabitants. Numerous studies were undertaken between 1992 and 2009 into constructing a tunnel to alleviate the bottleneck in Freiburg.

As the technical partner of the consortium, Vössing was commissioned at this initial stage to produce a preliminary design including a preliminary cost estimate for the tunnel based on the earlier studies. Particular importance was placed on the accuracy of the cost appraisal, which was to be suitable for extrapolating the approximate cost estimate from the preliminary design on to all of the project variants to be investigated. The preliminary studies considered a total of four design alternatives, which were supplemented by proposed variants from the consortium. The Stadttunnel Freiburg project called for a high degree of engineering experience, especially in the investigation of design alternatives (completion of work stage (WS) 2). This is because the influencing variables and interfaces arising from the direct surroundings of an inner city tunnel project and associated construction works required complex solutions from all specialist disciplines.

Engineering services

  • Project planning of engineering works WS 2
  • Consideration of alternatives
  • Project planning of engineering works WS 3 (optional)
  • Project planning of transportation facilities WS 2
  • Project planning for transportation facilities WS 3 (optional)
  • Planning of loadbearing structures WS 2
  • Planning of loadbearing structures WS 3 (optional)
  • Planning of technical fitting out WS 2
  • Planning of technical fitting out WS 3 (optional)
  • The approximate estimates were carried out in WS 2 in each case.
  • Special services: Safety documentation, Safety risk analysis, Ventilation design certification