[OSM-talk] "Incorrect speed limit" anonymous notes - who is behind that?

Shaun McDonald shaun at shaunmcdonald.me.uk
Tue Jul 29 12:24:06 UTC 2014

Hi Peter,

Unfortunately we don’t take account of any country defaults due to the complexities involved.

I’m sure that someone will come up with a tool to highlight the problems if a national speed limit does change, especially if the maxspeed:type is used appropriately.


On 29 Jul 2014, at 12:39, Peter Wendorff <wendorff at uni-paderborn.de> wrote:

> Hi Shaun,
> if I understand these maps correctly, they show streets without a
> maxspeed tag, but not msising maxspeed restrictions under the assumption
> of a national default or something like that (although it seems not so
> show any "missing maxspeed" in Germany, so there might be something like
> that applied).
> If maxspeed is and should be applied on any street, this works, but only
> until speed limits change.
> If you imply the default according to highway class and location, it
> fails as many roads do follow these defaults and cannot be counted as
> "missing", nor is it possible to decide where else a maxspeed is missing
> then.
> In any case reporting missing maxspeeds will work only until the speed
> limit is changed on the ground as it is even more difficult (if
> possible) to detect where there are errors (!) in existing speed limits.
> regards
> Peter
> Am 29.07.2014 um 13:10 schrieb Shaun McDonald:
>> Hi Peter,
>> The following ITO Map shows missing maxspeed tags where there isn’t any purple (mph maxspeed) or dark green (km/h maxspeed) colour:
>> http://www.itoworld.com/map/125?lon=-0.08316&lat=51.51851&zoom=14&open_sidebar=map_key&fullscreen=true
>> If you want to see the current speed limits see:
>> http://www.itoworld.com/map/124?lon=-0.08316&lat=51.51851&zoom=14&open_sidebar=map_key&fullscreen=true
>> Clicking the maps gives more info in the sidebar.
>> Shaun
>> Disclaimer: Employee of ITO World who produce the maps above.
>> On 29 Jul 2014, at 11:49, Peter Wendorff <wendorff at uni-paderborn.de> wrote:
>>> Sorry,
>>> there are QA tools to detect where speed limits are missing?
>>> Can you give me a link?
>>> And - if it's not self explaining: how should that work? I don't see any
>>> way to detect missing speed limits in the data beyond cases where those
>>> are implicit defaults, like 100 on non-trunk roads away from built up
>>> areas in Germany (which is complicated enough to derive from the data),
>>> or 130 for trunk roads (although most often there are lower limits), or
>>> 50 in cities (as the most often down-signed default).
>>> So if there is any QA tool that detects that, I fear it uses third party
>>> sources, a reporting system similar to the notes feature, but using a
>>> different channel, or it is restricted to some cornercases only. I doubt
>>> there is something like that which could make notes about speed limit
>>> errors in osm obsolete.
>>> IMHO notes are to be checked in person on the ground usually. If there's
>>> nobody in France to do that, yes, then notes will remain in the database
>>> for a long time, but basically they stay correct: Here is something
>>> missing or wrong, please check that on the ground.
>>> regards
>>> Peter
>>> Am 29.07.2014 um 11:09 schrieb JB:
>>>> I don't necessarily want to analyse once more how the notes are opened,
>>>> closed or not closed and to what aim, nor analyse the end of
>>>> OpenStreetBug life and the quality of the remaining bugs, but in France,
>>>> I have never ever seen anyone comment on someone else's note (or «
>>>> resurvey »). The only comments I have seen were from the note opener,
>>>> when prompted by a potential corrector.
>>>> So a note which indicates « probably 90km/h here » or « speed limit is
>>>> not 0km/h » may remain there for years (yes, years), demotivate
>>>> potential note closers, never be closed. I do not think they participate
>>>> to a high quality note db. There are quality assessments tools around
>>>> that allow contributors to detect where speed limits are missing.
>>>> JB, with perhaps some bad faith in there, but not that much.
>>>> Le 29/07/2014 10:19, Steve Doerr a écrit :
>>>>> On 29/07/2014 08:32, JB wrote:
>>>>>> Anyway, as for most notes concerning speed limits, if you do no have
>>>>>> the beginning and the end of the limit, at least in France, the
>>>>>> information is quite useless.
>>>>> Are we all armchair mappers now? Surely the note should prompt someone
>>>>> local to go out to the location and find out where the speed limit
>>>>> starts and ends?
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