The osm2navit script imports ways tagged with both highway=some value and railway=some value as railways and thus prevents navit from using them for routing.
Tagging ways as highway and railway is commonly used in OSM when for example tram rails are located directly on a road and tram and car traffic share the same space.
The way osm2navit imports this breaks the routing in my town and I'm sure it does in many places.
One solution would be to create two different ways in the mapnik file for the street and the rails, so the information is not lost - the other one could be to simply consider such ways as a normal street.
