[OSM-talk] A warning about gates and other barriers

[M∡rtin Koppenhoefer]

2010/9/20 Dave F. <davefox at madasafish.com>:
>  On 20/09/2010 09:07, M∡rtin Koppenhoefer wrote:
>> I prefer asuming that a gate is closed (I tag them with access=private
>> in these cases anyway)
>
> This is a bad assumption to have. Just because a gate is closed, it doesn't
> mean your not allowed access.


maybe I wasn't clear: I am tagging gates with the access-restrictions
that apply. I do this with access for closed gates
(access=private/destination) and with exceptions like foot=yes,
bicycle=yes, motorcar=yes. If applies, also add maxheight or height
tags.

I didn't care for motorcycles, wheelchairs, horses and others until
now, but sometimes information for those can be taken from the kind of
obstacle (gates exist in great variety why at least width is an
important extra information, but others like [1] are more predictable
for certain modes of movement) and I think we could also have
different tags for "pysically impossible" "allowed/forbidden". The
first can sometimes be expressed by width and height (and maxweight,
etc.), but not in all cases. The latter is what we usually describe
with access and subtags (foot etc.).


Another approach [2] to map physical possibility would be to define
all possible barrier types and every application can decide based on
the type and maybe measurements if it lets it's user through.


> barrier=gate means it's a gate & nothing else. It could be open/closed & all
> sorts of traffic could legitimately have access.


yes


> Tag what you see on the ground. If you don't know, don't tag it.


what also means: "no tag -> no information" - this is opposed to the
idea of defaults (which would be deriving the information from the
fact that a tag is _not_ set). I agree.


Cheers,
Martin

[1] http://wiki.openstreetmap.org/wiki/File:TR-a.JPG

[2] http://wiki.openstreetmap.org/wiki/Proposed_features/New_barrier_types#Tag_values