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Reference node ID 1349143672

I was recently using the OSMAND app to navigate and it directed me to make an illegal U-Turn. (I know it is illegal because my wife was stopped by the cops for doing it. Nothing to do with OSM.)

Anyway, I thought I would look at the OSM data and try to fix this. The situation is where a dual carrigeway ends and becomes a two way road. The restriction is that a U-Turn back to the other side of the dual carrigeway is prohibited. There is currently a no_U_Turn restriction in the OSM data but I don't think that is correct. No U Turn means one is not allowed to go back on the same path. I think the restriction should be No_Left_Turn back to the other lane of the dual carrigeway.

I tried to make this change in JOSM, but the validator complained that this restriction needs to be part of a relation. That is where I am stuck. I find this business of relations to be quite difficult and have gotten into serious difficulty messing with them in the past, so I thought it best to seek some guidance on this occasion.

Cheers.

asked 17 Dec '19, 17:27

dougcb68's gravatar image

dougcb68
1017712
accept rate: 0%


This relation looks close but needs the node where you can't turn back to the other side added as a "via" node - especially in this instance where it looks like the ways join at both ends (can you do a U-turn at the other end - that would need to be a second relation with a different via node and the from and to roles swapped).

Edit: if the roadsign says no u turn then that is the restriction type to use. In practice no u turn or no left turn in this instance with the same from and to ways and via node should work the same for routing.

permanent link

answered 17 Dec '19, 17:54

EdLoach's gravatar image

EdLoach ♦
19.5k16156280
accept rate: 22%

edited 17 Dec '19, 17:56

Good! That is what I was missing. I didn't realize the node was also needed as "via" in the relationship. This passed the validator. Thanks.

(17 Dec '19, 18:27) dougcb68

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question asked: 17 Dec '19, 17:27

question was seen: 869 times

last updated: 17 Dec '19, 18:27

NOTICE: help.openstreetmap.org is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum