[Tagging] layer=-1, rivers, bridges and tunnels

Peter Wendorff wendorff at uni-paderborn.de
Sat Mar 15 13:30:09 UTC 2014


Hi John,
yes, that's one possibility; knew that already, but thanks for pointing
the list to the link.

regards
Peter

Am 15.03.2014 14:16, schrieb John Packer:
> I believe there was a proposal for tagging a bridge separately:
> man_made=bridge. I think it would be really nice to have the actual outline
> of the bridge rendered
> Em 15/03/2014 10:02, "Peter Wendorff" <wendorff at uni-paderborn.de> escreveu:
> 
>> Hi,
>>
>> I agree partially with you here.
>> Yes, adding bridges in addition to the road is possible and may be a
>> good idea.
>> What we currently map as being a bridge in fact is the property of "the
>> road is on a bridge" instead.
>> Changing the current tagging scheme to "duplicate the corresponding
>> segment of the way and tag the bridge as a separate, but again linear
>> object" is worse in all but one point.
>> The only point this is better in is that a street with a continuous name
>> may not have to be splitted because of the bridge; but on the other hand
>> we do so for anything else, too: speed restrictions, footway or not,
>> highway type, surface and anything else; so it doesn't solve an issue
>> dedicated to bridges.
>>
>> On the other hand it doesn't solve the issue with multiple parallel ways
>> on the same bridge, e.g. considering a dual carriage way on one bridge
>> construction we currently map the property "road is on a bridge" again
>> on both parts of the dual carriage way independently, but it's
>> impossible to decide from the data (usually) if it's one bridge or two
>> bridges.
>> Your proposal to duplicate the way does not solve this issue either, as
>> you would still need two separate ways here.
>>
>> regards
>> Peter
>>
>>
>> Am 15.03.2014 13:25, schrieb André Pirard:
>>> Hi,
>>>
>>> I wonder why we make bridges split and split and split the roads.
>>> In reality, bridges are pieces of concrete or stonework at level -1
>>> under an uninterrupted foil of tarmac at level 0.
>>> Or at level 0 if it's understood that the renderer knows what's a bridge.
>>> And the renderer knows, as it draws two thin stripes beside the road.
>>> So, a bridge can be a little way segment overlaying the road.
>>> This lets the routing software ignore the unnecessary complication of
>>> having to account for bridges as part of the route.
>>> This lets the bridge having its own attributes, unrelated to the road,
>>> for example a different name.
>>> This makes obsolete discussions wondering if the bridge must be split in
>>> two because the road changes in the middle.
>>> Etc. etc., all pieces clutch in very neatly.
>>> And BTW, this is similar to tunnel=culvert which is an optional feature
>>> of a bridge and that surprises no one at layer -1.
>>> And now, if we put bridges and culverts at -1, the rivers or streams are
>>> normally at -2.
>>> Tunnels (inside which the road runs) should be segments too, at level +1
>>> or 0.
>>>
>>> I have tagged a number of streams and rivers at -2 -1 0 and I find it
>>> appreciable to have an instant view of where the complete main stream
>>> is, if not exaggeratedly long, as well as less prone to errors.
>>>
>>> Cheers,
>>>
>>> André.
>>>
>>>
>>>
>>>
>>>
>>>
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>>>
>>
>>
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