Zimmerberg Base Tunnel

[3] The NRLA initiative sought to provide better alternatives to the steep mountain railways across Gotthard, Ceneri and Lötschberg through the construction of a number of base-level tunnels that enabled trains to more rapidly and efficiently traverse the Swiss Alps.

[5][6] The local geography and location of the tunnel posed some challenges to the construction effort, such as the need to avoid impacting nearby urban development, as well as little cover being available at key areas.

This was created by injecting a precise mixture of cement and slurry via pressurized grouting pipes across 120,000 valves; areas were tested for potential weaknesses and promptly re-grouted where appropriate.

[8] The proposed Phase II of the Zimmerberg Base Tunnel is one element of the wider Rail 2030 programme, which has an overall projected budget of 21 billion Swiss francs.

Until Phase II is completed, capacity and speeds both remain heavily constrained by traditional routes; the Swiss Federal parliament has voted to include the work in its long term expansion plan for 2030–2035.