[Talk-us] Maxweight in the USA

Paul Johnson baloo at ursamundi.org
Thu Nov 5 10:30:43 UTC 2015

On Mon, Nov 2, 2015 at 4:50 PM, Mike Thompson <miketho16 at gmail.com> wrote:

> The number of places to the right of the decimal separator has meaning, it
> indicates the precision of the value. Thus
> 80,000 lbs <> 36.28739 metric tons, even though that is what the
> mathematical conversion produces. To say that the two are equal implies
> that the state has equipment (weigh bridges / truck scales) which can
> detect changes of as little as 0.02 pounds in a fully loaded semitrailer
> truck and that they actually care about such small variations (a change in
> the fifth digit to the right of the decimal of a metric ton value = 0.2
> pounts). One of the great things about OSM is that it does support multiple
> units.  Writing a parser to read the value of an OSM tag and convert to a
> common unit is easy to do for the data consumer (having just done it with
> the height tag).

 Just as we shouldn't tag for the renderer, we also shouldn't devise
humanly hositle tagging schemes, like forcing unit conversions on regions
that use a different system of measure.  That's a political problem
affected areas should work out with their governments, and we're just going
to have to deal with the fact we're working with multiple sets of units
until the last three holdouts get on board.
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