You might be interested in this article from Alessandro, the guy who makes Spatialite: https://www.gaia-gis.it/fossil/spatialite-tools/wiki?name=graphs-intro ht

You might be interested in this article from Alessandro, the guy who makes Spatialite: https://www.gaia-gis.it/fossil/spatialite-tools/wiki?name=graphs-intro https://www.gaia-gis.it/fossil/spatialite-tools/wiki?name=gr... It talks about the errors in Open Street Map data, and the consequences of that for railway routing.