On 2019-07-06 04:49, Colin Smale wrote:
It is an intrinsic danger of international projects that words mean
different things to different people. Hence the importance of keeping
things objective, and recording facts, rather than judgements. It's
about what things ARE, not what they are CALLED. It really doesn't
matter if the tag uses "unladen" or "empty" or "tare" or indeed
"abc001". What is important is that the chosen tag is well-defined, so
people can translate the data to what it does (or does not) imply.
For example (my definition):
Bogie = composite of 2..n axles sharing a common load-bearing mechanism.
Not to be confused with a Close-Coupled Axle Group where each axle has
its own independent load-bearing mechanism.
With unladen/tare/empty, this is probably not exactly the same as kerb
weight (Mass In Running Order), which includes things like fuel in the
tank. Or is it "dry weight" without even the weight of the brake fluid?
Is it defined as weight, or is it actually legally speaking mass? Which
value is most easily accessible for mappers? Which value is most useful
to data consumers?
This is an important point. Your average non-British layperson mapping
businesses who happens to come across a weight restriction sign won't
initially know the distinction between an axle and a bogie (guilty as
charged), let alone tare and dry weight, so there's quite a risk of
mistagging. Editor fields with human-readable labels can mitigate this
risk somewhat, but after a modicum of research, I'm still unsure as to
whether the signposted "empty weight" differs from "curb weight".
Personally, as an American, I don't have a problem with calling it
either "empty" or "unladen" weight. I initially confused bogies with
axles on the wiki, owing to "tandem" being much more common here, but I
still find "unladen" to be self-explanatory, if slightly exotic. Maybe
I've spent too much time pondering the maximum airspeed velocity of
certain birds.
Are there any jurisdictions that make a distinction between specific
definitions of "tare", "empty", "curb", or "dry" weight in weight
restrictions? If not, there's no need to overdefine the tag. We already
handwave about the definition of maxweight: does it refer to the weight
of the portion of the vehicle currently on the bridge, or the entire
vehicle? Different jurisdictions probably have differing definitions
while using similar signs. Even the difference between empty and gross
weight is insignificant for most trucks. [1]
To account for empty weight restrictions, a navigation application would
have to ask the trucker their empty weight or perhaps the truck's
make/model/configuration. It seems to me that the more important
consideration is whether the application presents the user with the
correct terminology. Whether the underlying data is based on uniform
definitions internationally would be more important for analysis use
cases, I suppose, but anyone trying to shoehorn the U.S. system of
weight restrictions into a coherent international system is in for a
world of hurt. [1]
[1]
https://www.energy.gov/eere/vehicles/fact-621-may-3-2010-gross-vehicle-weight-vs-empty-vehicle-weight
[2] https://wiki.openstreetmap.org/wiki/Key:maxweight#United_States_2
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