[Tagging] Feature proposal - RFC - gross weight

[martinq]

> With this it would be:
> - max_weight: the maximum weight of the complete vehicle (including
> truck and trailer, in the German traffic rules (Straßenverkehrsordnung,
> StVO) that's a "Zug"; if I interpret my dictionary right, in English
> it's a road train.

-1

There is no (common) restriction that limits the actual weight of 
truck+trailer, thus it makes no sense to define maxweight as limit for 
the complete train.

Let me explain:

http://commons.wikimedia.org/wiki/File:Zeichen_262.svg

limits the permissible weight of a *vehicle*. The truck and the trailer 
are TWO distinct vehicles (!), thus - for the sign given above - the 
truck alone and the trailer alone must stay below 5.5t. The complete 
train may have a weight up to 11t!

This it is not a good idea to define maxweight as weight limit for a 
road train. Instead we keep 'vehicle', the legislation of the country 
will define what is a 'vehicle'.

Mappers should not have to worry about the exact interpretation of 
'vehicle' in the context of semitrailers, agricultural tractors with 
trailers, etc.


> - maximum gross weight: (however the tag is called then): the maximum
> weight the complete road train is allowed to have if fully loaded.

This sign

http://commons.wikimedia.org/wiki/File:Vorschriftszeichen_7a_Gewicht.svg

restricts the gross weight. But for highest level of confusion and 
inconsistency, the Vienna Convention restricts the gross weight of 
"vehicle or combination of vehicles" and not just vehicles, thus 
contrary to the road sign above, the trailer must be included. I sadly 
overlooked this.

Thus if we define maxgross_weight per vehicle, the road sign cannot be 
tagged as maxgross_weight:hgv=5.5 as proposed. The proposal needs a fix!

Since it applies to "vehicles plus any trailers" and not just vehicles 
(which are defined differently). And defining it as vehicle+trailer will 
add confusion and may not work in the international context outside the 
Vienna Convention countries.


Any suggestions how to fix this?


a) Introduce maxgross_train_weight=X?


b) Keep maxweight=X, flush maxgross_weight (looks odd anyway) and add a 
new tag:

maxweight:type=gross_vehicle, gross_train, laden, empty, etc.
to qualify the maxweight?

I would additionally define that the definitions + _weight can be used 
as properties in conditional restriction, eg. maxspeed=80 @ 
(empty_weight>5.5).

This suggestion also has better backward compatibility and it also 
enables country defaults.
Drawback is that only one maxweight-restriction per way is possible.

Opinions?

martinq