[Tagging] maxspeed:type vs source:maxspeed // StreetComplete

Tobias Zwick osm at westnordost.de
Tue Sep 18 17:41:17 UTC 2018

There is a misunderstanding.

So, there are 597 towns, 77 counties and 2 councils in the state of
Oklahoma and I understand that you want to say that all these entities
have authority over defining the default speed limit(s) within their
borders, right?
But if they do set a different default speed limit for their town, then
they will post signs for that.

What I mean with default speed limits are speed limits that apply *when
no sign is posted*. These kind of speed limits that are known (learnt in
driving school) by heart by drivers and usually explained in parts on
big signboards at country borders [1].

These defaults are with very few exceptions always defined state- or
country-wide, because, claro, noone can be expected to know the special
default speed limit that applies only in your town/country. Even if
there it is only signposted once at the city limits, it still counts as
signposted - perhaps as a (large) speed zone [2].


On the US-situation:
I have read many legislations on maximum speed limits for various US
states and know how they are structured and can follow where the above
misunderstanding is coming from:
In US-American legislations, on the one hand there are general
regulations that define the type of default speed limits that I refer to
(in- and outside built-up areas, state highways, interstates,...), which
are expected to be known by drivers.
On the other hand, there are oftentimes very specific regulations for
places like "on Cobe Island", "in this and that county", "on state
highway 3", even something like "Interstate 8 from this to that
Oftentimes, both types are defined in the same article, though, the
latter type is rather a list of instructions for the road transport
department where to put the speed limit signs (e.g. "school zones" have
to be signposted with the explicit speed limit in every state I
researched so far).

For some states, it is not clear from the legislation whether a road
type belongs to the former or latter category, such as in Iowa:
Will all or any of "state board institutional roads" (45mph), "state
park and preserve drives" (35mph), "suburban districts" (45mph),
"residence districts" (25mph), "business districts" (20mph) be
signposted with explicit speed limits? Or are drivers expected to
somehow know when they are on roads like these?

This is actually the major difficulty when researching US legislation on
default speed limits, and local knowledge is required to solve this.
This is why ask so many times in the forum for help by locals (, e.g. of:)
https://forum.openstreetmap.org/viewtopic.php?id=63295 (Kansas)
https://forum.openstreetmap.org/viewtopic.php?id=63000 (Iowa)
https://forum.openstreetmap.org/viewtopic.php?id=62976 (Indiana)


[1] for example at Czech border:
[2] see for example https://en.wikipedia.org/wiki/30_km/h_zone

On 18/09/2018 01:07, Paul Johnson wrote:
> On Mon, Sep 17, 2018 at 4:42 PM Tobias Zwick <osm at westnordost.de
> <mailto:osm at westnordost.de>> wrote:
>     In order to find an optimal and future proof tagging schema for default
>     speed limits, I believe that first extensive research have to be done to
>     find out what exists in the world, what has to be considered. Also, for
>     default speed limits to be actually used and understood by data
>     consumers, meta information needs to be collected about how to translate
>     road types to actual default speeds per vehicle type for each
>     country/region.
>     I started this (both) here, if you want to help, you are welcome:
>        https://wiki.openstreetmap.org/wiki/Default_speed_limits
> This is a Sisyphean task even by OSM standards.
> Just in my state, Oklahoma, there's 597 towns, 77 counties and at least
> 2 councils of governments (a regional government type thing between
> multiple cities), for about 46,000 possible sets of default rules.  In
> /one state/, and a rural one at that.  Out of 50.
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