It existed up until the pandemic, Trenhotel, I took it once. Fell asleep in the center of Madrid, woke up in downtown Lisbon. The trip had beautiful snowy landscapes lit by the full moon. It's such a shame it's gone.
There used to be one going directly from Northeastern France near Basel to South France Cerbere. It was the best one for going on vacation from Germany. They killed it because it wasnt profitable enough :/ Now you have to go through Paris which is a horrible stop to have to take.
Unpopular opinion. Night trains are never going to make a dent in air travel.
I've traveled right across Europe by train a bunch of times, so I've taken a good few night trains. In Germany, France, Austria, Switzerland, Denmark, Italy, a couple in the Balkans, even the Dogu Express right across Turkey. I've also taken day trains everywhere, of course.
Every single experience on a night train was something of an ordeal. That's because a night train is basically a hostel on wheels. Staying the night in a tiny cabin in extreme proximity to strangers, without privacy, without access to a decent bathroom, this is just never going to be competitive with a short flight, no matter how cheap it is. For students, young people and more adventurous types, sure, it's a great idea.
The only genuine solution to the plane problem is high-speed rail that is fully competitive on price.
There is another answer: improve comfort in night trains.
Being able to eat in a restaurant in a country A, sleep in a comfy night train and eat a breakfast in a country B would be way more comfortable than a flight imho.
The problem is that for most people over about 21, the biggest component of "comfort" is privacy. This is why people book hotels rather than hostels, even when the hostels are stylish and luxurious. Of course, night trains can be hotels-on-wheels too. The better ones have first-class cabins with private bathrooms. But this makes no sense from an environmental point of view. At this point you might as well take the short flight.
The best couchette-style service in Europe right now is the recently introduced Nightjet mini-cabins. Capsules, basically. This is a major step forward IMO but I still don't see this tempting most normie travelers. And so expensive, too.
Funny that there are pairs of trains from Krakow to Gdynia or Prague to Zürich that have the same termini but very different routes. Imagine going to Innsbruck only to wake up in the middle of Germany.
That looks fine to me. I'm no civil engineer but the lines connect on both ends, so a person can hop off and go to taranto, or stay along the top coastline. I'd assume the lines were doubled because people used that line so often that it was better to just create a whole new one.
I tried it once to get to London for a meeting. The best way I can describe it is this: if you manage to go to sleep, it's great, otherwise it's horrible.