[Tagging] weight limit in short tons

Andrew Hain andrewhainosm at hotmail.co.uk
Mon Jan 28 21:51:35 UTC 2019

As a quick objection from a British mapper old enough to remember obsolete measurements: long tons are pointless, too similar to toes and not used on signs anywhere I know of, the abbreviation st can stand for a stone (6.3kg or 14lb).

From: Warin <61sundowner at gmail.com>
Sent: 27 January 2019 23:11
To: tagging at openstreetmap.org
Subject: Re: [Tagging] weight limit in short tons

On 28/01/19 04:24, Sergio Manzi wrote:

On 2019-01-27 17:53, OSMDoudou wrote:

Indeed, it's very strange to require mappers do the maths when there is a notation to indicate the unit and let the renderers do the maths.


Why do you talk about math? Do you expect renderers to automatically convert weights from whatever unit to the one you're using for your locale? Or maybe to use those weight limits as a parameter for the router?

Yes. The renders have to cope with different units for speed, length, height, elevation etc. so why not weight?

As has been said before - far easier to find an error in the rendering and correct it than
find an error in the maths used by a single entry or a single mapper in the data base.

If this is what you want, then the problem is the parsing of the string used to define the units used within the tag: as already pointed out, "ton" is the symbol used for both "long" (UK, imperial) and "short" (US, cental) tons, so we must find a "controlled" way to indicate which measurement system is in use for the tag.

On the wiki page for units there is now the default unit of the tonne (metric ton for usa), and then alternative units of st for short ton, lt for long ton.

I just recently add the lt for long ton, the short ton was already there. If you want to add other units .. do so.

If the mapper uses the unit 'ton' then they have not complied with the wiki and
there would need to be a decision on using it at all, if using it then what unit is to be used.

If instead we are not interested in possible computations, then we can live with the customary way to indicate tons, and deduce from the location which kind of tons we are talking about, same as if we were traveling to the place and see the indication on a sign, with our own eyes.

And indeed the same heuristics can possibly be applied to a parser...


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