A very interesting and impressive site, I must say.

Lots of things I didn't know, but the fact that in Alsace-Lorraine
the trains still use the right track, whereas in the rest of France
the trains keep to the left is very interesting.

(By the way, there are still some other differences between Alsace-
Lorraine and the rest of France, e.g. in legislation (some old German
laws are still in force) and religion (the official French separation
of Church and State, 1905, is not in force, but a Concordat with the
Vatican).)

Of course trains don't change over that easily at borders, so
normally there is a certain stretch where trains drive on the "wrong
side" near borders. I know that there is such a stretch between
Roosendaal (NL) and Essen (BE). The thing probably occurs on other
BENL border stretches as well. But here the train safety system is
not of the type that makes it possible to drive both tracks in both
directions with this system working. On stretches like that, a
sign "VS" (Verkeerd Spoor = Wrong Track) is put at the beginning of a
track that is driven on in the "wrong" direction. It is put there to
remind the train driver that he is going to do something which is not
supervised by the train safety system in force, and that it is
imperative to have a special mandate, obtained at the last station,
to drive on this track in this direction (a so-called "Lastgeving
Verkeerd Spoor"). Roosendaal - Essen is interesting in the respect
that rail traffic is on the left track, Belgian style, rather than
right, Dutch style. So here the right track is marked by "VS" signs.
I know that there is one right at the border, when driving north,
which is a bit of overkill I'd say because you would be driving on
the "Wrong Track" in Belgium as well before that. But it is useful
for trains leaving Roosendaal for Belgium. A train driver could make
the mistake that it is quite normal for his train to enter the right,
and not the left, track.

Peter S.