[Tagging] "Feature Proposal - RFC - bicycle=use_cycleway

Ronnie Soak chaoschaos0909 at googlemail.com
Thu Nov 14 12:35:37 UTC 2013


Robert argued here that country-specific restrictions should be always
expressed by tags so that routers don't need to know those specific
rules/laws.
He gave the maxspeed tags as an example, which we explicitly tag even if
they are based on implicit laws.

I think this generalization is goes too far.

For the access tags (and we do discuss access tags here), it is common
practice to have country-specific defaults on certain highway types as
listed in the wiki [1] and only tag what contradicts those defaults.
I don't see why it would be needed to switch that to explicitly tagged
values. Opposed to maxspeed, we are talking a large set of different tags
here where both tagging as well as legislation is in constant change.

Based on these asumptions, I would argue that it would be enough to specify
if a compulsory exist or not and leave the details of which type of vehicle
can under which conditions use the road or not to the router, which should
implement those based on national defaults. So at least the legislation
changes can be implemented at a central point.
(This is already the default, so no additional change needed for that.)

I would prefer an additional tag over a replacement for bicycle=no, as this
would allow an easier migration due to not breaking older routers. (This is
why I would vote 'no' on the proposal.)

I would also say that stating that there IS a compulsory cycleway is a
first step, but not enough. To check for certain conditions (width,
direction, reachable destination, obstacles, surface), the router would
need to know WHICH way is the compulsory cycleway.
We can either do this with a relation combining the highway and the
cycleway(s) or with tags and self-created references. I would clearly
prefer the first.

I think neither storing all the information needed for those decissions in
the highway tags (instead of the cycleway tags) would be a doable
workaround nor pre-interpreting them by the mapper and
tagging the result on the highway. As stated above, those interpretations
would be based not only on (ever changing) local administration but also on
very subjective opinions.
As a user, I'd rather have those opinions baked into the routers I can
chose, not in the map data all routers have to use.

My 2 cents,

Chaos



[1]
https://wiki.openstreetmap.org/wiki/OSM_tags_for_routing/Access-Restrictions#Germany
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