The Grimsel Line would link Innertkirchen in the canton of Berne and with Oberwald in the canton of Valais, uniting the ZB, MGB and Rhaetian Railway (RhB) to form a continuous 844km narrow-gauge network across central and southern Switzerland.
The 22km line would run for much of its length in an 8.3km single-track tunnel. A company was founded last year under the name Grimselbahn to take the proposals forward and a feasibility study encompassing geological, technical and economic aspects of the project has been completed.
In addition to the railway, the tunnel will accommodate high-voltage electricity cables, which are currently routed over the head of the Grimsel Pass and Grimselbahn has formed a partnership with Swissgrid to develop this side of the project.
The cost of the project, estimated at SFr 580m ($US 583m), will be shared by the two partners on a user-pays basis as both parties agree, sharing a single tunnel will cost considerably less than building two separate tunnels.
The cantons of Berne and Valais have already applied to the Swiss Federal Office of Transport (BAV) for financing for the construction of the tunnel from FABI, the Swiss rail infrastructure fund. The parties involved in the project hope to gain planning permission by the end of 2019 with the aim of opening the tunnel in 2025.
Grimselbahn forecasts the line will carry around 400,000 passengers a year with an hourly service in both directions.
This is not the first time plans have been made for a tunnel under the Grimsel Pass. The project was first put proposed in 1860 and has been revived several times since then, but always fallen victim to political considerations.