Understanding concepts iro drawing a rail line starting and ending at two given stations

I am very new to overpass.

It seems to me that a line is a set of ways all with the same ref tag value (they are also all railway tag - rail). For example:

out geom;

a) I am struggling to understand why some ways making up this line have just one or two nodes to define them and some have a huge number of nodes.
b) It seems to me that all of these nodes are tagless nodes, with just coordinates, which leaves me at a loss to know how a rail line’s ways’ nodes can somehow be associated with stations as would be necessary to selectively draw a line from one station to another. The ways’ nodes and the station nodes seem quite separate things.

My thinking had been to identify a station node and from that somehow identify the set of ways that make up the line this station is on.

However, taking the set of ways in the example above, if I quite separately identify a station I know to be on this real world line and its node id that id is not amongst any of the nodes included in the ways that make up that line, only the tagless nodes.

I realise I have more understanding to gain but until I can get past any misconceptions / misunderstandings at this point then I am a bit blocked.

3 posts - 2 participants

Read full topic

Ce sujet de discussion accompagne la publication sur https://community.openstreetmap.org/t/understanding-concepts-iro-drawing-a-rail-line-starting-and-ending-at-two-given-stations/104796