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

Niels Elgaard Larsen elgaard at agol.dk
Mon Jan 4 00:36:53 UTC 2021

På Sun, 3 Jan 2021 22:14:50 +0100 (CET)
Mateusz Konieczny via Tagging <tagging at openstreetmap.org> skrev:
>Surveying maxspeed is clearly useful and relatively[1] simple.
>But surveying and tagging cases where there is no signed maxspeed and
>it default to what is specified by law is often problematic.
>(1) we have no tag for "there is no maxspeed signage applying here"

I use e.g., source:maxspeed=DK:urban

>(2) default maxspeed rules are often extremely complex
>For example Poland has separate speed limits for
>- vehicles below 3.5t
>- vehicles with trailer or above 3.5t or trucks
>- buses

But does that depend on whether the maxspeed is signed?

For example in DK the maxspeed for busses is 80, except that some
busses can do 100 on motorways.

The default speed on motorways is 130, but it is often signed as 110.
But it can be lower at interchanges or roadworks.

So for a bus on a motorway its max speed is just min(100,maxspeed)
Everywhere else it is min(80,maxspeed)

>(3) tagging exact max speed is often de facto impossible as it 
>requires remembering that there are separate rules for
>- dual carriageway with 2 or more lanes in each direction
>- dual carriageway with 1 lane in each direction

That does not sound so impossible.
You would hope that most drivers could figure it out.

>- roundabout
>- urban road that is not a roundabout
>(El Salvador)
>- road without asphalt or concrete surface
>- road with asphalt or concrete surface in an unincorporated area
>For more gory details
>(4) tagging exact speed limit info therefore requires both survey to
>confirm that no signed speed limits applies and legal analysis (or
>using output of that) and extra information. Right now mapper is
>supposed to do both in one step what is not feasible.

I have done tens of thousands of speed limits in DK mostly based on
Mapillary. It is quite feasible.

There has been a few places where it was not possible. That was mostly
because of just wrong signage. Eg. a maxspeed=40 sign from one
direction and a maxspeed:advisory=40 sign from the other side. Or
missing city limit signs. That will be a matter of waiting for new
Mapillary images, doing a survey, or contacting the city.

>Having "maxspeed:signed=no" to tag "there is no signed maxspeed here,
>no speed limits signs, zoned speed limit does not apply, default
>legal regulation apply"

How would that add more information than source:maxspeed=DK:rural,
source:maxspeed=DK:motorway, etc.?

> would allow sane survey that does not require
>consulting local legislation to tag speed limits.

Just record images for Mapillary (or OSC or something).
Tagging maxspeed by just survey is difficult outside residential areas.

I have fixed many errors. It was typically because someone had made a
survey and tagged a way with maxspeed without checking if there was any
signs on that way.

And I have spent a lot of time searching for signs, that I knew had to
be there, but I would most likely have missed had I just surveyed.

E.g. spot the city limit on:


>[1] speed limit zones, max speed differing depending on direction,
>speed limits applying only to some vehicle types, speed limits
>applying only on specific times etc all exist.

Yes, I have tagged all those in DK.

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