[OSM-talk] [tagging] Feature Proposal - RFC - Clearance

[Martin Koppenhoefer]

2009/8/1 Renaud MICHEL <r.h.michel+osm at gmail.com>:
> Le vendredi 31 juillet 2009 à 03:23, Roy Wallace a écrit :
>> What about a way that has either a physical limitation or a legal
>> limitation (not both). Perhaps there is some argument that the tag
>> should differentiate between these situations? Though I admit I can
>> only think of a weak one - that it makes it clearer for users and
>> mappers
>
> I have a very good example:
> For an ambulance, many legal limitations (like speed limit) don't apply, so
> if a road has a legal limitation for the maximum height of 2m but you can
> actually physically take that road with a 3m ambulance, that is a useful
> information for the ambulance driver who then knows he can actually take
> that road, although regular users may not.

This is a nice theory, but can I see some example? I doubt that there
is any bridge with 3 m height and 2 m restriction. And I doubt that
the ambulance driver would (in case of emergency) have the time and
nerves to check if a bridge with 2m- restriction will still have
enough space for him to pass. And I won't recommend him to rely on OSM
data. Can you imagine what happens to him, if he gets stuck under a
bridge with designated maxheight (and he's bigger) with an emergency
patient on board?

I don't neglect the usefullness of this tag though: there might be
special transports (accompagnied by local police) that might pass
(with special permission and controll) a bridge that legally is
restricted e.g. to 2,80 but physically allows even 3,00 m to pass.
They will even get rid of some air in their tires if it is needed ;-)

cheers,
Martin