Displaying countries is very easy. You just need to do add country to graph.encoded_values, run a new import (!), and request the corresponding country path detail.
Ok, then it would be the exact same as for traffic_signal. It does not matter what kind of node tag it is. Or are you wondering how to implement a railway router?
Ok, I don’t know the details of OpenRailRouting. But for speaking of the GraphHopper code reading railway=border for railways should be the exact same as reading traffic_signals for highways.
Thank you guys very much (@karussell and @easbar). I managed to make it work. However, I noticed that railway=border does not return the precise location of a train station. Any idea why?
In OpenStreetMap <tag k="railway" v="border"/> represents the point of where exactly the border is, but I need the location of the train station where the transition happens. Note: it gives the correct train station name but not the location. Tag:railway=border - OpenStreetMap Wiki