[Tagging] maxspeed:signed=no - new proposed tag

[Volker Schmidt]

This reply is to Martin mainly: if you are convinced of this proposal, and
I am completely confused, I  guess I have to ask you kindly to explain how
you think this could work.
My reference frame is UK, Germany, Italy, Austria.
In these countries you have

   - zoned speed limits,
   - street-category speed limits
   - locally on the ground signed limits (for node-like objects or
   stretches of road)
   - In addition you have certain categories of vehicles that have their
   own limits which may or may not be visible on road signs

Zoned limits means that there is a sign indicating the beginning of the
speed limit that is valid until you enter the sign (or road junction in
some cases) that cancels it.

   - country-wide non-urban with the exceptions of a couple higher speed
   road classes
   - built-up areas: from the city limit sign to the end-of-city sign you
   have respect the XX:urban speed limit
   - zone 30 and similar
   - speed limit zones with start-speed-limit signs and end-speed-limit
   signs or ending at the next major road junction

zone-speed limits can be nested (e.g. zone 30 in a built-up area)

Default speed limits by road category: motorway, other dual-carriageway
extra urban roads

Default limits by vehicle category, normally defined for the same
zones/roads

Then there are very local speed limits that are valid on node objects in
OSM, like road bumps or pedestrian crossings (they end implicitly behind
the object)

Italy has some strange weather-dependent speed limits on motorways (50km/
for "fog" an 110km/h foer "rain")

Now to OSM:
I notice that in many cases road-type ways do not yet have a maxspeed tag.

In which case is the proposed tag to be set?

   1. Only when I am surveying on the ground or by armchair mapping *with*
   street-level imagery, and I am not sure what the value is (because I did
   not pay attention or whatever),
   2. Also when I am  armchair mapping *without* street-level imagery

*case 1* is relatively rare and I would possibly use "fixme=speed limit to
checked" (no need for the proposed new tag)

If the proposed new tag is to be used in *case 2* on all streets that are
not yet mapped with any speed limit, I would prefer a narrowing-down
approach with tagging of the type  "likely-maxspeed=50|90|..."
This would certainly be in keeping with the mentioned idea of good
approximation.

Volker





On Sat, 9 Jan 2021 at 14:55, Martin Koppenhoefer <dieterdreist at gmail.com>
wrote:

> I’m convinced, just use maxspeed:signed=no and let’s move on ;-)
>
> Cheers Martin
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>
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