[Talk-GB] [Fwd: Re: Speed limits]

Dave Stubbs osm.list at randomjunk.co.uk
Fri Sep 21 10:13:15 BST 2007

On 21/09/2007, Mark Williams <mark.666 at blueyonder.co.uk> wrote:
> Looking to map uses, we're going to be wanting routing, to know how fast
> a given route is; or a warning if over speed, from GPS (as nothing else
> knows our location..). So we will have software using it. Is someone in
> 'foreign parts' going to know / care about us using mph? No, so we'll be
> the only people in the world who can't use their products! Does it
> matter if we get the speed warning in error at 29.825817mph instead of
> 30? Really? Does it matter if it misreads it silently, and doesn't beep
> 'til 48? Yup. What if the mph has a typo, does the s/w have to interpret
> pmh or kmph? It's worse for a maxspeeed_units=mph tag :)

Typos in tags are a whole other issue entirely... if someone mistyped
redidential you're likely to be floating in space, or doing some sort of
off-road challenge, or have a serious lack of cake, depending on how you
wish to interpret the road not being on the map.
And you're right in that the difference between 29.825817mph and 30mph isn't
going to cause anyone any problems.

The argument here is that it is just wrong. It's an approximation being made
because the model can't cope. Well, we have that problem all the time, but
in this case we have a very simple fix, so why not apply it?

I'm definitely against this idea!
> For the record, I have no great urge to go metric ourselves; I just want
> things to work, and perceive a  point of failure in this. I realise that
> programmers can easily add a comversion routine - but why cause the
> problem? It's like the Millenium Bug - a bit of forethought would have
> prevented all the hoohah, and work to make it all OK - & we coped with
> that too, but can't we learn a lesson??

Yeah, if we'd just thought ahead the map feature would have stated from the
beginning that you should state your units. I remember my physics teacher at
school was very insistent on people stating their units. Leaving the units
off is quite a bit like not bothering with the first 2 digits of the year
for whatever reason.
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