N5 Solothurn – Biel, Tunnel Birchi

The Birchi tunnel is a section of the N5 highway in the Canton of Solothurn (N5/2 section Nennigkofen – Zuchwil.

Dati principali

  • Type of tunnel: double tube with 2 lanes per driving direction
  • Length: 2 x 1'400 m (2 x 700 m underground, 2 x 700 m open-cut)
  • Profile: horseshoe profile with bottom slab (in open-cut section base plate)
  • Excavation cross-section: 100 m²
  • Geology: lower fresh water molasse
  • Type of heading: pilot tunnel with partial excavation of roof section, face and invert, excavated with part-section machine
  • Stations: at both portals
  • Ventilation: longitudinal ventilation (jet ventilators)
  • Infrastructure: power supply, lighting, safety/ communication equipment, supply of water for fire fighting


Office for National Roads of the Canton of Solothurn


IUB Engineering Ltd. in consortium

Periodo di costruzione


Costi dell'opera

160 Mio. CHF


  • Construction project
  • Tender and comparison of tenders
  • Execution project
  • Supervision of works
  • Documentation on the project

According to the terms of reference of the overall project management, the consortium - under the leadership of IUB (certified according to ISO 9001) - drew up a QC plan with annual audits for all partners (project work and supervision of works).