WMS is good for raster images, unfortunately not for vector data.
There is no uniform standard for vector data. Several file formats coexist, some originating from ordinary desktop graphics, some from CAD and others from cartography and GIS. Even more complicated is the search for vector data sources. While many countries, surveying agencies and transport infrastructure owners like railway companies will have completed digitizing their data in the last decade, the data is rarely available to the public, at least not for free. Furthermore, the majority of the is data will still be 2D.
The 3D shaping capabilities in the TransDEM vector data export were originally added to satisfy my curiosity whether it can be done at all and what the output would be like. To create my test data I went the DIY way.
I used an external CAD like track laying editor and tool-set which comes with the German rail simulator Zusi (
http://www.zusi.de). Those tools were quite difficult to use and no proper English interface or documentation exists but they produced superb quality 3D vector data. The next version of Zusi, currently only available to industrial and research projects, has a much more user friendly track laying CAD tool. However, license restrictions might prohibit its use for non-Zusi projects.
There used to be a CAD tool for model railway layouts which was also capable of generating 3D data and export it to a common file format but I don't know whether that's still available.