What is the best way to map a one way turnstile, for instance as a ticket gate at a subway entrance? So far I’ve mapped it as a one way footway with a turnstile node in it, but I understand from the wiki that tagging a footway with oneway=yes doesn’t have any effect because that tag is always interpreted as not having an effect on pedestrians. The alternative foot:backward=no is very little used, though, so may not be considered by routers as well. Or could this be solved by adding oneway=yes to the turnstile node (in combination with the direction of the footway that it is part of)?
I’d say the wiki page for key:oneway gives quite a clear answer to your question:
Although unusual, oneway on pedestrian highways (path, footway, track) is possible in some countries. While it is sometimes represented with the disputed tag: oneway:foot=* it has been argued that the tag foot:backward=no should be preferred, as it doesn’t suffer from the problems of the former. In the past highway=path + oneway=yes was used by some mappers to mark that pedestrians may move only in one direction, these situations should be corrected, as oneway in OSM only applies to vehicles. Furthermore a highway=path may be open to others road users such as cyclists.
Adding oneway=yes to a node is not encouraged by the wiki.
Neither of these answers is very attractive, I think. One proposes a little used tag, the other to use a value of the entrance key which could be the second on the same footway if there are sliding doors before it. See this situation, for instance
Having tagged the sliding doors with
entrance=entrance/exit, it would be strange to tag the swing gate ticket barriers behind them with the same tags…
I hope this question and this discussion will eventually lead to consensus and some firm advice on the wiki about how to map these one-way pedestrian situations.
I do not see the problem here. Tagging the sliding doors with entrance/exit is fine. Putting the turnstiles as nodes on the (indoor mapping) footway is fine. Adding foot:backward=no to make clear that pedestrians can only move in one direction is fine as well. The tag is clearly defined, documented in the wiki and in use. It could not be much better imho.