Can you remember how absurd it was to travel back then? Of course, you can't, you weren't even born. We looked at the stars so bad we wanted to be the closest possible to them at all times. We thought the future was in the sky, with flying cars and planes all above us. Ah, it's been over two centuries but I still remember vividly how foolish we were at that time.
Aerial travel is not as trending as it was before. It is slow, unpractical, and cannot be maintained while in service. The main advantage is that skyways take no space compared to railways, but even this point is questionable on dimensions like Terra or The Impossible World. Planes and helicopters are still in use in certain places where railways are not fully developed or the ground is hostile, but that is about it. Furthermore, airborne vehicles work badly with interdimensional travel.
Trains proved to be a much more reliable way of transportation, especially with the advance of magnetic tracks and 0G acceleration. Even the shortest Terran train runs at 500 kilometers per hour and manages to stop in less than 50 meters without the passengers feeling any acceleration. It does put enormous stress on the structure, however, and the trains are more often maintained or replaced than they would be with a more careful approach. Of course, Terra is not lacking in material or manpower and thrifty considerations do not go far.
Across the dimensions
A planet-class train can get around a dimension in less than an hour, or two if the network is not sufficiently developed. However, crossing the space between dimensions is not as straightforward. The interdimensional medium is a strange one, not like anything else. Most materials get corroded or break apart in minutes, which is an inconvenience when it has the same effect on people. Interdimensional trains are bulky and sturdy, able to withstand incredible amounts of pressure and of course the strain induced by the interdimensional medium.
They are completely isolated with no window, as even the slightest glance at what lies behind the heavy metallic curtain is enough to kill people, turn them mad or join the Cosmic sect. They cannot protect the passengers from the uneasiness generated by simply being in this unconventional space. Engineers tried to make up for the feeling by providing many amenities and top-class comfort to distract the passenger from their physical unwell-being. For some people, it is still not enough, and around 5% of the total population has been diagnosed with interdimensional sickness that makes them unable to get out of their dimension without falling ill for several weeks afterward.
The IDT for Aquerias will depart in ten minutes. Estimated arrival between fifty minutes and twelve hours, at 5:17 pm Aquerias time. Make sure you forgot nothing in the station before leaving.
Travel time through the interdimensional space is non-linear. Several factors have been identified, such as the fact that two dimensions may not have the same flow of time or be far away from each others. A part of random probably comes into play somewhere, as two trips are never of the same duration. Hence, a common idiom is to say that with IDT, you may know when you depart but never when you reach your destination. If you are lucky, you emerge at the other side before you can even open a book, and if not you can finish a whole saga in the meantime.