[Talk-gh] Unverifiable speed limits resulting from organised mapping in Accra

[Enock Seth Nyamador]

Dear Hajar and TomTom (mappers),

In reference to my comments on your maxspeed=* mapping in Accra [1]. 
There are multiple frightening maxspeed=* from this mapping which are 
completely unverifiable. I also see roads which of course lead nowhere 
and were results of other organised mapping campaigns tagged with 
maxspeed=* without any further investigation.

I would have expected that this kind of organised mapping is discussed 
publicly and documented on the OSM Wiki.  As of 2024-08-23, there is 
only one road in Accra on OSM with verifiable speed limit of 100 km/h 
[2]. Seeing roads in dense Accra Central even with existing adjacent 
verifiable maxspeed=50 tagged with higher maxspeed=90/100 [3][3a] makes 
me wonder. I have also seen lower maxspeed values where there exist some 
street-level images to validate eg. way [4] (maxspeed=30) and Mapillary 
image [5] (street sign 50).

TomTom's mapping team I believe is better aware and in the position to 
post-process all roads wherever and add whatever desired speed, see 
Default speed limits [6], but outsourcing to a bunch of newbies to add 
into OSM, is not what OpenStreetMap is about.

As I have always commented on this list and elsewhere there is just too 
much useless data from many undocumented organised mapping activities in 
Ghana that needs to be deleted in the end, hence we don't want to see 
new problems that will never be fixed.

The practice of setting up a series of maproulette or HOTOSM Tasking 
manager instance projects and letting it fix itself is not helping but 
continues take place from multiple actors in Ghana and elsewhere.

Please kindly find the best way to undo all maxspeed=* resulting from 
this organised mapping campaign without damaging existing valid ones 
e.g. manually, contact DWG, etc.

1. https://maproulette.org/browse/challenges/48926
2. https://overpass-turbo.eu/s/1TCn
3. 
https://www.openstreetbrowser.org/#map=17/5.54911/-0.20774&basemap=osm-mapnik&categories=car_maxspeed
3a. https://overpass-turbo.eu/s/1TCC
4. https://www.openstreetmap.org/way/169135203/history/7
5. 
https://www.mapillary.com/app/?lat=5.551382553813923&lng=-0.19400795959847983&z=19.9&pKey=517473239420891&focus=photo
6. https://wiki.openstreetmap.org/wiki/Default_speed_limits

Best,
Enock