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

[Mark Williams]

Liz wrote:
> On Tue, 28 Jul 2009, Roy Wallace wrote:
>> My main point is that when there is a "maximum height under a way",
>> this should be tagged as an attribute of that way, not of the ways
>> that pass under it.
> 
> Here I cannot agree
> When I travel over the bridge I am not interested in the maximum height of the 
> way which travels under the bridge.
> 
> When I travel under the bridge I am interested in the height limitation.
> 
> Going back to my multipart specification, trying to really comprehend the 
> logic
> 
> the height of the arch is a property of the bridge.
> the max height which can go under the bridge is a property of the way / node 
> beneath it
> 
> note that counter-intuitively, height > max height > clearance
> 
> 

May I just observe that when you go along a road, you will see 
'maxheight' notices when you *enter* that road, frequently.

This means an overheight vehicle cannot use that road.

It can't use all except the little bit with the restriction.

Therefore maxheight is a property of the way going under the bridge, 
possibly >1 way if the road is fragmented in OSM, and ought to be on the 
whole road from where the sign is until after the bridge.

Also, although the sign may be physically attached to the bridge, it is 
placed to be visible to traffic on the way crossing beneath it, not to 
traffic on top so people can think "oh look how interesting" as they 
pass over it...

Obviously sat-nav type applications should be able to cater for point 
restrictions, however the OSM idea is much more about recording what's 
there & signed than about tagging for specific app's or renderers.

I think the idea of tagging the bridge is odd, and failing to tag the 
way beneath irresponsible. If I see a maxheight on a bridge, I will 
*know* there is another layer above it.

My 2p..

Mark