Roundabouts are not analyzed correctly by relation analyzer, when they are connected to oneway part

[PetrDlouhy]

Roundabouts are not analyzed (sorted nor visualized) correctly by relation analyzer, when they are connected to oneway part like this:

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More examples are on ticket #5109, see testing cases in roundabout-and-oneway-loop_(tricky).osm​ and example 1 in more complicated cases in relation_analysis.osm​.

[PetrDlouhy]

There is little controversy about this, which I am not sure, how to treat:

When the orientation of oneway loop is opposite to orientation of the roundabout, one part of the roundabout will be driven twice (or never in case of same orientations), when going from beginning of the relation to end and backwards.

This could be contradiction to system, in which oneway parts of the relation are understood. It inconsistency appear more intensively, when trying to split the roundabout into several forward/backward parts - the twice (or never) driven part should, probably be included twice (or never) in the relation.

This will lead to inconsistent relations, when somebody the roundabout without any knowledge about the relations on them.

[stoecker]

NOTE: Validator component reports roundabouts in routes as broken as well.

[PetrDlouhy]

Hm, even plain roundabouts are leading to inconsistency with forward/backward logics, when spitted. I am not sure, how JOSM should deal with that.

There should have been wider agreement about the relation treating in whole OSM, not just JOSM. I didn't find anything on OSM wiki, but I hope my improvements will provoke some discussion about this as well as other implementations.