Simutrans seem to support height title reservation - it's impossible to build crossing bridges.
However, behavior of this feature is inconsistent / bugged.
a) City / factory / curiosity builder completely ignores height factor. It's possible to build bridge over every city and factory, no matter how high it is. Also, city buildings will pop under bridges overlapping them.
b) While power line builder takes height title into account - it's impossible to build lines under bridges, it doesn't reserve it after construction. It's still possible to build bridges over already created lines.