The new Gotthard train tunnel, which opened on 1 June 2016, might have a serious design flaw.
Next December, Swiss Rail plans to start running high speed trains through the tunnel. The planned speed of these trains is 200 km/h. There are now fears that the tunnel is too tight to run trains this fast.
As trains zip through tunnels they push air out of the way. Some of this air has to pass down the sides, between the train and the tunnel.
The new Gotthard tunnel’s section is 10% smaller than the Lötschberg tunnel, which runs 14.612 km under the Alps between Speiz and Brig, a train trip taken by some residents of Bern on their way to Zermatt. In addition, there are no additional spaces at the tunnel’s sides to balance the air pressure. Then there is the challenge of coordinating these trains with freight trains travelling at 100 km/h. In the end, it might be that trains can only travel through the tunnel at 160km/h or 180km/h. Talking to the newspaper NZZ am Sonntag, a CFF manager said “We’ll be lucky if it works as planned.”
It seems the engineers who designed the tunnel, might have underestimated the quantity of air, the extent of the air pressure at the front, and the air vacuum created at the back. Full scale tests were planned and have already started.
In 2019, the challenge could become greater. New EC250 trains made by Stadler, will come into service. These are 17cm wider than the trains used today and will displace more air. Stadler however, has brushed the concern aside.