Gotthard Base Tunnel: through the heartland of the Alps

Deep below the Swiss Alps, the longest tunnel of the world has been created after a 17-year construction phase. For freight transport, it’s a challenge to cross the Gotthard Base Tunnel, as the conditions in the inside are unusual.

Mit rund 100 Stundenkilometern rauscht der Güterzug in den Tunnel. Vor ihm liegen 57 km in der Dunkelheit, umgeben von unglaublichen Gesteinsmassen. Bild: Thomas Küppers

With 100 km/h, the freight train whizzes in the inside of the tunnel. It faces 57 km in the dark, surrounded by incredible rock masses. (Picture: Thomas Küppers)

It has been a project of superlatives: deep below the Swiss Alps, the longest tunnel of the world has been created, after a construction period of 17 years. For freight traffic, the crossing of the Gotthard Base Tunnel is challenging, as the conditions in the inside are unusual. Therefore, the cargo-securing experts of the Bielefeld branch have examined on behalf of the Swiss Railway Cargo, which influence the tunnel crossing has on the cargo.

With 100 km/h, the freight train whizzes into the tunnel. In front of him are 57 km of darkness, surrounded by incredible rock masses – during that time, up to 2300 metres of mountain massif are above it. During its travel through the heart of the Alps, temperature is around 40 degrees, the air is humid. High, rapidly changing dynamic pressure mean a significant strain to the mechanics. The longest train tunnel of the world, the Gotthard Base Tunnel places high demands on its “traversers”. In future, there will be many of them: around 260 freight trains will cross the tunnel every day and commute between Zurich or Basel and ChiassoMailand or LuinoBusto Arsizio/Novara.

In Summer 2016, the tunnel has been opened officially. To guarantee the safety during transport of goods, the Swiss Railway (SBB) Cargo AG has conducted test drives in January and April 2016, together with the DEKRA branch of Bielefeld. „We were asked to examine how different strains influence the cargo and wagon material. The second question to what extent the speeds planned, might jeopardize the operational safety“, says project leader Wolfgang Bühren.

Im Sommer 2016 wurde der Tunnel offiziell eröffnet. Um die Sicherheit beim Transport von Ladegütern zu gewährleisten, führte die Schweizer Bundesbahn (SBB) Cargo AG zusammen mit dem Ladungssicherheitsbereich der DEKRA NL Bielefeld im Januar und April 2016 Testfahrten durch. Bild: Thomas Küppers

In summer 2016, the Gotthard Base Tunnel has been opened officially. To guarantee safety in the transport of goods, the Swiss Railway (SBB) Cargo AG has conducted test drives in January and April 2016, together with the DEKRA branch of Bielefeld. (Picture: Thomas Küppers)

Crossover in the middle of the tunnel

The DEKRA engineer was able to win the big German body construction companies to participate in the project and to test differnt constellations with them: On the first test, various forms of combined traffic on a train have been tested for the first time with a train consisting of 21 wagons, with a length of over 600m and a total weight above 1500 t. In the beginning, the permitted speed was at 100 km/h. In further test drives, they examined to some degree, how a speed of up to 120 km/h and a crossover from the east to the western pipeline of the Gotthard Base Tunnel would influence the cargo.

The first results of the six test drives in January have been validated in April under exacerbated conditions. The entering and leaving of the tunnel had been done at a speed of 120 km/h, including a crossover from one pipeline into the other. Additionally, empty wagons have been put between every of the container wagons to create maximum pressure.

Die ersten Erkenntnisse aus den insgesamt sechs Versuchsfahrten im Januar wurden dann im April in einem verschärften Test validiert, bei dem auch die Tunnelein- und ausfahrten mit 120 km/h gefahren wurden – einschließlich der Spurwechsel von einer Röhre in die andere im Berg. Bild: Thomas Küppers

The first results of the six test drives in January have been validated in April under exacerbated conditions. The entering and leaving of the tunnel had been done at a speed of 120 km/h, including a crossover from one pipeline into the other. (Picture: Tomas Küppers)

Endurance test for locks

After ten test drives trough the Gotthard Base Tunnel, the experts gained some valuable insights: “We now can say that strains due to acceleration which occurred at different speeds and during the crossovers, have been significantly below the limit values of the technical regulations,” concludes Bühren. “For a tunnel ride with 100 km/h there are no irregularities to expect, all required standards are fulfilled under these conditions.” The only problem that occurred was the use of a single-use UIC-conform covering sheet for one of the empty waggons. “The covering sheet didn’t hold, the eyelets have been partially torn out and the covering sheet has been almost entirely blown away by the wind, luckily only to one side of the waggon,” says Bühren. But also with the semitrailers with lateral sliding covers – the so-called curtainsiders – there have been some problems. At test rides with 120 km/h, 70 per cent of the locks without a threaded customs cable and even 30 per cent with a threaded customs cable failed, depending on the construction. “The vibrational strains during the tunnel crossing are extremely high. This is why braking mechanisms in the belt lock of the covers are indispensable”, explains Bühren.

 

Auf einem ersten Versuchszug mit 21 gezogenen Transporteinheiten über 600 m Länge und über 1500 t Gesamtgewicht wurden erstmals die unterschiedlichsten Arten des kombinierten Verkehrs in einem Zug geprüft. Bild: Thomas Küppers

During the first test, various forms of combined traffic on a train have been tested for the first time with a train consisting of 21 wagons, with a length of over 600m and a total weight above 1500 t. (Picture: Thomas Küppers)

In August, DEKRA presented the test results of the Gotthard Base Tunnel in front of an expert team of 12 members in the headquarter of the SBB Cargo. Currently, the SBB introduces them as a basis for the necessary changes of regulations in front of the international associations.

Now, the DEKRA experts for load securing from Bielefeld are waiting for the next field tests of their measurement technology, which has been adapted to combined traffic together with the department AG 21 of the DEKRA headquarter. The next tunnel to be tested is the Ceneri Tunnel, the last section of the so-called flat-level rail track trough the Alps to Italy.

Text: Anna N. Wolter

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