Trans-alpine rail routes

The capacity of major European rail routes is limited. Investment in national rail networks always had priority over international routes. The European Union policy document Roadmap to a Single European Transport Area says that:

  • “30% of road freight over 300 km should shift to other modes such as rail or
    waterborne transport by 2030, and more than 50% by 2050”
  • “By 2050 the majority of medium-distance passenger transport should go by rail”.

However it does not allocate funds for any new infrastructure, and that would be essential to meet such targets. The limits of the existing network were illustrated, when volcanic ash from Iceland closed west European airspace in 2010. Rail services were completely unable to transport the millions of stranded air passengers.

Trans-Alpine rail routes are an example of limited capacity. There are more roads than railways over the Alps, but both have capacity problems. The Alpine rail networks (Switzerland and Austria) include many single-track, curving, low-speed lines. An effective rail network across the Alpine barrier would require a vast amount of new infrastructure.

Alpine relief map by user Perconte under CC 2.5 licence.

Relief map of the Alps

The Alps do not consists of a single ridge with foothills. The topography is more like a series of mountainous blocks, separated by river valleys. There is a choice of strategies to cross them. There are shorter routes with several passes, or longer routes following the valleys, usually leading to a single high pass over the main watershed. This explains why trans-Alpine routes have shifted through the centuries.

The earliest rail lines duplicated existing pass routes, and were named for the pass. These lines tried to minimise expensive and dangerous tunnelling. The new generation of trans-Alpine tunnels are much longer, and not necessarily under a pass. That has made a new approach possible: tunnel chains through several of the mountain blocks. The alignments do not follow the river valleys, but instead use them as breaks in the tunnel chain – to provide construction access, and for safety.

Here all main rail infrastructure corridors to/from northern Italy are listed, even if they do not cross the main Alpine range. The list is long, so it is split into the western and eastern Alps. The present, planned, and possible rail infrastructure is indicated for each corridor, including new high-speed lines (HSL). The list includes classic routes following the topography, and tunnel chains. No claim to originality: rail lines and tunnels have been proposed all over the Alps, at some time or another.

In a clockwise direction the corridors are:

The railway directly behind the beach at Ventimiglia. Image by Florian Pépellin, licence CC 3.0.

Coastal rail line at Ventimiglia

  • Col de Tende route Nice – Cuneo – Torino, single-track diesel line. (At present this is operated as an Italian line Torino – Ventimiglia, with the Nice line as a branch).
  • Provence – Gap – Briançon- Torino. A new 22-km rail tunnel would create a trans-Alpine inter-regional rail route to Oulx in the Susa valley. Briançon is connected to other regional rail lines to Grenoble, Valence, and Marseille, but this is not a main trans-Alpine route.
  • Fréjus route: the existing line through Chambery from the Saône valley, and the Fréjus tunnel connecting to the Modane – Torino line. A new high-speed line and base tunnel, the Liaison ferroviaire Lyon – Turin is under construction.
  • Chambéry – Aosta regional line, via the existing Tarentaise line to Bourg St.-Maurice, a new 24-km tunnel under the Little St Bernard pass to Pré-St.-Didier, and the existing Aosta valley line to Ivrea and Torino. This regional line would connect with the main Lyon – Torino route, but it is longer, and links no large cities.
  • Geneva – Aosta – Torino corridor, via a new 20-km Mont Blanc rail tunnel from Chamonix. This is potentially a strategic route, but the existing standard-gauge Arve valley line ends at St. Gervais, and the line to Chamonix is metre-gauge. A new line would be needed over most of the corridor. The southern tunnel portal would also be near Pré-St.-Didier, connecting to the Aosta valley line.
  • Great St. Bernard corridor, with new base tunnel from Martigny to Aosta. There is a 6-km road tunnel under the pass, but a base tunnel would be about 45 km long. This is potentially a second strategic route from Paris to northern Italy, via Dijon and Lake Geneva, but it would require a new HSL across the Jura, parallel to the singe-track Vallorbe line, and a HSL along the Aosta Valley, which is densely populated.

Aosta in the Val d’Aosta. Image by Francesco Sisti under CC licence.

  • Lötschberg axis Bern – Milano, the western axis of the AlpTransit project for new Alpine crossings in Switzerland (NEAT in German). The existing line is an early tunnel chain, with the Lötschberg tunnel and the Simplon Tunnel. The new 35-km Lötschberg Base Tunnel is in use since 2007, although only one bore is complete. The AlpTransit / NEAT project includes improvement of the approach lines, as far away as Basel, see the list of Schweizer Eisenbahnprojekte.
  • Gotthard axis Zürich – Milano, the second axis of the AlpTransit project. The original Gotthardbahn was opened in 1882, and is limited in capacity by curves and spiral tunnels. The new 57-km Gotthard Base Tunnel is under construction, and the project includes more tunnels along the approaches. The planned maximum speed is 200 km/h, creating a trans-Alpine HSL.

Spiral tunnels on the Gotthard railway.

The Splügen Pass is traditionally the boundary between the eastern and western Alps. The corridors and lines east of the Splügen route, are described in the second half of this post: Transalpine rail: eastern.

Trans-alpine rail routes

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