Bike turn restrictions

Continuing the discussion from Add support for complex turn restrictions:

@OlafFlebbeBosch what is your opinion regarding turn restrictions for bike?

My opinion is and was that in practise I would probably not take a large detour only because of a turn restriction as I can instead get off the bike and cross the road via walking. But sometimes this might not be possible (illegal without crosswalk in certain countries?) or unsafe for larger roads? At least it should be configurable like for car and we should include this special “get-off-bike-walk” turn instruction to not violating the law.

Furthermore for cargo bikes this special turn with walking is very likely no option.

Hi @karussell, yes fully agree, but the situation I was pointing to is a bit different: There is an “unechte Einbahnstrasse” (not a real one-way) here: sign 267 no entrance. IIRC there seems to be a general consensus on OSM to model it with a turn restriction. Not ideal if we route people over this sign. We discussed it internally a lot and for now concluded we want not spend that the additional efforts for turn on turn restrictions only for this edgy case.

Ah, ok. I see.

Do you have an example for this?

Isn’t this more a mapping problem and should be mapped via a node with access restrictions?

update: ah, no. access depends on the direction and it would be necessary to map it as a very short oneway.

The example is here : Relation: 11234410 | OpenStreetMap

And I will check to find the OSM discussion again.

“Unechte Einbahnstraßen” are not that uncommon, some cities seem to love them and have multiple of them. Here is one more example: Relation: 3409861 | OpenStreetMap

Thanks! Really strange why this isn’t mapped as a much simpler and more explicit tiny oneway.

At least it should be configurable like for car

btw: this is already possible using the same config bike|turn_costs=true.

Yes, I just tried it and you can simply skip the graph.flag_encoders entirely and just set turn_costs: true in your (bike) profile.

I’d like to hear the reasoning behind this. And also how do other OSM tools deal with this, e.g. does carto draw the little one-way arrows based on this information? It seems a lot harder compared to simply checking for the oneway tag.

@easbar I do not know the rationale behind it:
in DE:Key:oneway - OpenStreetMap Wiki

Inzwischen wird die Variante mit einer Restriction-Relation bevorzugt. Der Tag innerhalb der Relation ist dann z.B. restriction=no_entry. Zu beachten ist gegebenenfalls auch der tag “except” an der Relation, um Ausnahmen (z.B. für Fahrradfahrer oder Anwohner) zu mappen.

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