[OSM-talk] Bridge reference tagging and relations

David Earl david at frankieandshadow.com
Sun Aug 10 18:18:58 BST 2008


On 10/08/2008 17:47, Gervase Markham wrote:
> Why, then, should such a relation be
> necessary for a simple task such as adding a reference to a bridge?

If you want to apply a bridge number to the bridge, there's no reason 
you shouldn't, vote or no vote. And if something were to render it, not 
doubt it would look right.

However, the thing you are putting the number on has no easy linkage to 
the canal. If you were boating along the canal and wanted your satnav to 
pop up the next bridge number, it would have a hard time doing that 
because there's nothing actually linked to the canal to tell it.

Of course it could do some tests to find out what bridges pass over the 
canal by analysing more data in the area, but these are complicated 
tests. By relating the bridge to the canal you are attaching the bridge 
number with the thing it is relevant to - the canal - rather than the 
thing the bridge is attached to - the road crossing it.

David





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