Designated direction for railway tracks

[Zverikk]

Oneway tag is not applicable to railway=rail (and others, like railway=subway), because there are no legal obstacles to trains going either way. But usually there is a common direction of travel. Mappers use these tags to specify it:

• ​railway:preferred_direction=forway/backward/both
• ​designated_direction=forward/backward/both

These tags are used on 61k and 3.5k objects respectively. Could you please add both, ot at least the first one, to presets and the map style? It would help mappers not add oneway=yes on railway tracks and hint at the correct tagging.

Also it'd be great to validate railway+oneway combilation and suggest a better tagging.

[Klumbumbus]

Hm, currently there are ​88k ways with railway=* + oneway=*, which is more than the 61k ​railway:preferred_direction.
Is there a clear statement from the "railway fraction" of OSM about this tagging topic?

[Zverikk]

Yes, oneway is not formally applicable to railways, since trains are not forbidden by law to go in opposing directions. Oneway is a kind of access: think of it as "access:backward=no". For that reason two railway communities — german and russian — invented these two tags to map designated directions of railway tracks.

[Zverikk]

Also see a comment about oneway here: ​https://wiki.openstreetmap.org/wiki/OpenRailwayMap/Tagging#Railway_Line