[Tagging] Pedestrian access tagging

[Minh Nguyen]

Vào lúc 05:06 2021-01-23, Andy Townsend đã viết:
> On 22/01/2021 23:24, Volker Schmidt wrote:
>> There is this wiki page on Default Access 
>> <https://wiki.openstreetmap.org/wiki/OSM_tags_for_routing/Access_restrictions>, 
>> which shows that this is country-dependent
>> I do not know to what extent this is taken into consideration by routers.
>>
> Obviously, it depends on the router.  In some cases I suspect "it 
> isn't"*.  The instance of OSRM that is linked to from osm.org doesn't 
> like foot routing on trunk roads - see 
> https://www.openstreetmap.org/directions?engine=fossgis_osrm_foot&route=54.0440%2C-0.9416%3B54.0410%2C-0.9469#map=14/54.0414/-0.9253 
> .  That router is hosted in Germany, where as I understand it things 
> tend to only get tagged as "trunk" when they are also "motorroad=yes", 
> so perhaps it's applying "normal German tag usage" worldwide.

Neither OSRM's default foot profile nor FOSSGIS's customized profile 
considers the motorroad key for any purpose. [1][2] This key and the 
default access restriction page linked above are just some of many 
aspirational heuristics that have been developed for routers apparently 
without significant involvement from router developers. File this in the 
how-did-it-ever-work drawer. ;-)

With something as impactful as access restrictions, a router would incur 
some risk in suddenly starting to use motorroad for access restrictions. 
I'm reminded of the time that OSRM started avoiding construction=*, but 
people starting getting odd routes because of construction=* tags that 
lingered well after highway=construction had been changed to 
highway=motorway. [3] Nevertheless, it's worth opening a request for a 
special case to consider considering motorroad, now that OSRM supports 
country-specific rules. [4]

[1] https://github.com/Project-OSRM/osrm-backend/search?q=motorroad
[2] 
https://github.com/fossgis-routing-server/cbf-routing-profiles/blob/9358cab13e55e61bea14da3534c0398a18f194d8/foot.lua
[3] https://github.com/Project-OSRM/osrm-backend/issues/4462
[4] 
https://github.com/Project-OSRM/osrm-backend/wiki/Using-location-dependent-data-in-profiles

-- 
minh at nguyen.cincinnati.oh.us