Flagship Projects

Complete renewal of the Kerenzerberg tunnel

Maximum safety thanks to new cleat

«The new safety tunnel, which serves as an escape route in the event of an incident, significantly increases safety in the Kerenzerberg tunnel. The renovation of the structure also ensures the long-term operation of the tunnel.»
The Kerenzerberg tunnel has been part of the Swiss A3 national highway since 1986. The link is important from both a regional and national perspective. The overall renovation project includes a new 5.5-kilometre-long safety tunnel and the repair of the existing tunnel system.

With a length of around 5700 meters, the Kerenzerberg Tunnel is the fifth longest road tunnel in Switzerland. The tunnel, which is located on the Swiss national highway A3 in the canton of Glarus, is particularly important for regional commuters and leisure traffic. Nationally, the tunnel serves as part of the alternative route between the Gotthard and San Bernandino routes on the north-south axis.

The two-lane road tunnel first opened to traffic in 1986. As no major repairs have been carried out since then, the infrastructure no longer meets current safety standards. To adapt the road tunnel to today's guidelines and standards, the tunnel will undergo extensive renovation in the coming years. On behalf of the Federal Roads Office FEDRO, Lombardi, as part of the "INGE K2" joint venture, was responsible for drawing up the detailed project, the tender documents, preparing the implementation documents and on-site supervision.

The main part of the project involves the construction of a new 5.5-kilometre-long safety tunnel. This runs parallel to the road tunnel at a distance of around 20 meters. The safety tunnel is divided into two sections: The upper part serves as an exhaust duct for the main tunnel in the event of an incident. In the event of a fire, the resulting fumes can be quickly removed from the tunnel area. The lower part of the tunnel serves as an escape route and as a plant duct. Cross-connections link the tunnel to the main tunnel every 300 meters. As additional measures, the structure of the road tunnel was renovated, and the entire operating and safety technology was renewed. The comprehensive overall renovation project will therefore not only benefit today's users, but also the generation of tomorrow.

  • Conventional and TBM tunnelling
  • Cavern and shaft construction
  • Tunnel safety
  • Technical buildings
  • Renovation
  • Excavation support and ground improvement

meters - length of the new safety tunnel.


meters - distance to the nearest emergency exit.


meter - Distance between the main tunnel and the safety tunnel.


meters - diameter of the safety tunnel.

Lat: 47.125
Lng: 9.1159


230914 kerenzerberg tunnel CH Gi C 15
«In the event of fire or other emergencies, every second counts: thanks to the new and innovative tunnel, the safety in the Kerenzerberg tunnel can be massively increased - and will be for many years to come.» Manuel Wipfli