I'm new to osm and poking around between the docs and map. I came across this node shared between this railway and this footpath.

A check of the raster on google maps shows that it's a dirt path that crosses the train tracks.

Is this correct? To me this suggests you can "transfer" between ways here.

asked 12 Nov, 14:58

zappytoes's gravatar image

accept rate: 0%

It may be questionable if a dirt path crossing a railway line should be mapped at all. But leaving that question aside the situation is correctly mapped.

You can see that the node in question is tagged with railway=crossing wich highlights this exact situation. And of course you can transfer between the ways here. Nothing physical (no level difference, wall, ...) stops you from sverving off the path and continue walking on the tracks.

And only since the two ways share a node is it obvious for a data consumer that both ways are physically connected. A router may give you a warning walking along the path that you have to watch out for trains.

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answered 12 Nov, 15:24

TZorn's gravatar image

accept rate: 15%

edited 12 Nov, 15:27

Thanks, I see how that tag works in this situation.

My ultimate goal is to understand route/directions algorithms, so I was curious what info I would use to deal with that node.

(12 Nov, 15:41) zappytoes

Roads can be connected to all sorts of objects: landuses, buildings, waterways, bridges, ...

I guess for routing purposes you would create a graph of only routable ways (roads for cars, roads (but not motorways) and paths for pedestrians, etc.). What's routable can be determined by the way's primary tag but also by access and some other tags. So if you think a pedestrian shouldn't walk along railroad tracks you would exclude those from your graph alltogether and you would not be concerned about the node at all. Of course it's not that simple (nodes might constitute barriers) but you get the gist.

(12 Nov, 18:42) TZorn
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question asked: 12 Nov, 14:58

question was seen: 123 times

last updated: 12 Nov, 18:42

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