Routing does not support :forward and :backward modifiers on access keys

[eisams]

Organic Maps will happily route you through forbidden routes, this is not allowed:

See how Valhalla does it: https://www.openstreetmap.org/directions?engine=fossgis_valhalla_car&route=59.91734%2C10.75949%3B59.91877%2C10.75936

These are generic access modifiers that can apply to any normal access tag e.g., vehicle, motor_vehicle and bus

The specific way in question: https://www.openstreetmap.org/way/17844#map=19/59.91809/10.75935

(The Valhalla routing will change at the next update, as it routes through a set of roads that I corrected destination only access)

[biodranik]

Looks like motor_vehicle:forward=no is ignored, right @vng ?

[vng]

908 occurrences, https://taginfo.openstreetmap.org/keys/motor_vehicle%3Aforward#overview
Not mentioned here:
https://wiki.openstreetmap.org/wiki/Key:motor_vehicle
I suspect it is not a valid mapping. Is it the same as putting oneway=-1 ?

[matkoniecz]

I created https://www.openstreetmap.org/note/4301123

Not mentioned here:

well, :forward and :backward prefixes can be added to anything but this usage seems like a pointless overcomplication and trap

http://overpass-turbo.eu/s/1Na6

though you have say https://www.openstreetmap.org/way/1271671965 with motor_vehicle:forward=destination that has no obvious replacement

[harahu]

Tricky this one. The street is oneway, but only for motor_vehicles, and even then with two exceptions:

• Busses are allowed to drive this direction when servicing a route.
• Goods transport is allowed.

In light of this I feel like a blanket oneway=yes would be misleading unless one can specify the exceptions well enough in a way that most routers understand.

[matkoniecz]

I expect that no tagging will work well in most routers as case is quite rare.

[harahu]

I am digging into the documentation on these kinds of restrictions. Some observations:

• The pattern currently used is described here: https://wiki.openstreetmap.org/wiki/Key:oneway#Interpretation_for_routing. Hence, it isn't entirely undocumented.
• This is a case of a https://wiki.openstreetmap.org/wiki/Key:oneway#False_oneway_streets_(Faux_oneway). So perhaps a restriction relation should be used in this case, rather than tagging the way directly.

[harahu]

I guess you mean this: valhalla/valhalla#4203

[eisams]

I deleted my ugly replies by email, just wanted to say that it is implemented by Grasshopper, Valhalla and OSRM
Valhalla implemented it after I reported it last year

The relevant tags for the routing modes supported in OM:
https://taginfo.openstreetmap.org/keys/motor_vehicle%3Aforward#overview (900)
https://taginfo.openstreetmap.org/keys/vehicle%3Aforward#overview (800)
https://taginfo.openstreetmap.org/keys/bicycle%3Aforward#overview (6000)

https://taginfo.openstreetmap.org/keys/motor_vehicle%3Abackward#overview (1200)
https://taginfo.openstreetmap.org/keys/vehicle%3Abackward#overview (800)
https://taginfo.openstreetmap.org/keys/bicycle%3Abackward#overview (6700)

[eisams]

FYI: Just checked and OsmAnd also support these tags, and even shows it as one-ways. (albeit with a very interesting route, didn't know you could take that shortcut)