[OSM-talk] [talk-au] maxheight/height

[Maarten Deen]

Roy Wallace wrote:
> On Tue, Jul 28, 2009 at 2:57 PM, John Smith<delta_foxtrot at yahoo.com> wrote:
>> As of time of writing maxheight is the only valid one and I don't think we
>> need or should have 2 tags to indicate the
> same thing in 2 different ways.
>
> I meant there's two ways of conceptualising the distance below a
> bridge (as an "attribute" or a "restriction"). I'm not suggesting we
> need 2 different tags. I'm quite happy to tag it as a "restriction",
> if we can agree on how it should be implemented.
>
>> have a node on the way effected, near or under the bridge, rather than
>> splitting the way and then tagging that node as maxheight or clearence might
>> be the better option that making a new section of way. However maxheight is
>> currently only applicable to ways not nodes.
>> ... It's not hard or ambiguous, it just means splitting a way under the
>> bridge similar to splitting a bridge.
>
> I would at least suggest that - if maxheight is applied to a node, as
> you suggest - the node should be *shared* by the bridge (way) and the
> way passing under. This makes it clearer that maxheight is

That seems a very bad idea. Nodes are generally used to indicate a physical
path between two ways. Having a node shared between a bridge and the way
underneath may solve one problem but introduces another (having to make a
relation to indicate this physical route is not present).

> specifically referring to the bridge clearance. Also, if someone is
> checking, for example, whether maxheight is specified for a particular
> bridge/way, they don't have to go searching for some random node
> "near" the bridge.

But why am I interested in a bridge clearance? I am interested in the maximum
height my vehicle can have while traveling down a road. I can argue exactly
like you that I don't want to go searching for some random node "near" the
road I'm travelling on to see if it is possible to do so.
If you are on the bridge, you are not really interested if the bridge poses a
limit to the way underneath it.


IMHO there are people here trying too hard to model things. maxheight does not
necessarily need to be applied to bridges only. It could also be powercables
or tramlines or low streetlighting or branches or whatever.
maxheight needs to be applied to the road it applies to. Not the structure
that is going over it. If you want to do that (which is not that uncommon,
water maps do it all the time), introduce another key.

Regards,
Maarten