[Talk-GB] Maxspeed tagging for the UK

Andy Robinson ajrlists at gmail.com
Fri Apr 15 09:57:02 BST 2011

From: Kai Krueger [mailto:kakrueger at gmail.com] 
Sent: 15 April 2011 02:17
To: talk-gb at openstreetmap.org
Subject: Re: [Talk-GB] Maxspeed tagging for the UK



Richard Fairhurst wrote:
> Why are we doing this?
> In OSM we optimise for the mapper, not the data consumer. That means we
> tag exceptions, not majorities.

+1 / -1 (Yes and no)

It has to be a compromise with which both sides can live with, mappers and
application developers.

If a tagging schema is too complicated for mappers to add, but easy to use
for data consumers, it is of little use, as the data won't get added. But
vice versa, if the data is easy to input, but too complicated for data
consumers to ever feasibly use, then that is also fairly useless. It will
just remain dead data, filling up a database.

Both sides need to be adequately represented in the thoughts of what good
tagging schema's are.

In most parts of the world, mappers are the limiting resource, so a good
compromise will sway towards being easy for the mapper, but it still has to
be a compromise.

Unfortunately if we thought anything other than the simplest way for mappers
then OpenStreetMap would never have got off the drawing board. I agree in an
ideal world the data would be perfect for entry AND use. But we don't live
in a perfect world so we must look at it differently. Data users need more
tools to help them sanitise and make the data more applicable to their
needs, especially if those users have limited skills or software/hardware
platform, but it's post processing tools and alternative data formats  that
will help overcome the inherent disadvantages of not realistically being
able to ask mappers to do more complicated data entry.

If I am not mistaken, you your self have said that you would rather use
Ordinance Survey data then OpenStreetMap data, despite being an absolute OSM
enthusiast. And if I remember correctly, this was not only due to licensing,
but also because of ease of use?

But that aside, this particular issue has actually been the mappers who want
to note down national speed limit tagging and has not been a "request" from
data consumers, as far as I can tell. Mappers wanted to distinguish between
"no explicit speed limit/ national speed limit" and "no one has surveyed the
speed limit, so I need to go there to survey it". At least that is what I
remember from the very long discussions on just this topic on talk-de.

This is why assuming something on the absence of data is much more reliable
than assuming the data is correct. As more gets mapped the data becomes less
complete because different mappers map different things in different ways
for any given area. Relying upon all roads to carry the appropriate tag is
far more dangerous an assumption that assuming something where no tag



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