in a first step you could take a planet file and filter out only the
objects you need. Then you could import the filtered data into a
database, e.g. with osm2pgsql. With a PostGIS database you are able to
do many different geographic queries such as getting all nodes that
are part of a way or calculating way lengths.
Thanks for that. In that case I'll stick with the "path" tool in Google
Earth though.
I had just hoped that someone would have actually thought of
implementing a user interface for extracting information from
Openrailwaymap. But, well, "web application" and "user interface",
those two things just don't seem to fit.
Sincerely,
Wolfgang