[Motel75]

Hmmm. I don't think this explains why when I take the train from Warsaw to Berlin, the very good service is completely lost at the German border. There could be several factors: there may be repeaters on the train that only work with Polish networks, or the providers in Poland have targeted railway lines as must-cover areas, which the Germans have not. Indeed, the service along many German railway lines is appalling, and it has nothing to do with fast trains or metallic coating on the windows. At the same time, service is always very good along the autobahn; it seems the German providers may have different priorities.

One thing that should be noted is that the vehicle speeds Inquisitor mentions apply if the vehicle is directly approaching the tower. This may be the case with cells in tunnels, but will not be so with towers placed some distance away (the relative speed can be figured out with the cosine of the angle of travel relative to the tower; if the train is perpedicular to the tower the relative speed is zero).