[OSM-dev] Making polylines from route relations

[Paweł Paprota]

Hi,

It is trivial to do in PostGIS (ST_LineMerge) or anything that can deal
with standard (OGC) geospatial types, e.g. RGeo in Ruby.

However from my experience I can tell you that working with route
relation geometries is very tricky because of how they are mapped. At
least for road and bicycle relations to get a real picture of the route
you need to take into account ways that are NOT in the relation but are
tagged with appropriate "ref". Otherwise if you consider only ways from
the you will end up with a lot of disconnected components in your
geometry.

Anyway, not sure what do you plan to do with those routes but in the
last few weeks I have done a lot of work (e.g. [1]) with road and
bicycle (and also boundary but that's OT here) relations/ways so I can
share if you have specific questions.

Paweł

[1]https://wiki.openstreetmap.org/wiki/OSMonitor/Poland_Major_Roads