[OSM-talk] problem with HOT mapping in Niger

John Whelan jwhelan0112 at gmail.com
Sun May 9 21:51:41 UTC 2021

Thanks Andy,

I used to do a lot of validation on HOT projects.  However to make it 
work you needed to contact the mapper in a very short time frame.

These days I have my own set of tools which I use to clean up the map 
especially in Africa.  I can clean up the errors in an area that covers 
the HOT project much faster than going through the HOT validation process.

I must confess if I see a dozen highways with name=road on them I have 
been known to remove the name=road tag.

I have left a comment on the HOT project.

I have got feedback from the mapper who changed at least one 
highway=unclassified, their comment was

"OK ... The highway specifications for this missing map project are 
simple for mapping : tracks ou residential ... but further a global 
validation will be led with more details for major roads connecting 

This mapper happens to be the person who has validated most on the 
project.  The instructions are in many ways fine if it applied to new 
highway that were mapped as part of the project.  You could simply do a 
clean up afterwards but what seems to have happened is a large section 
of the map has had many highway=unclassified etc. highways reclassified 
to track and that is a bigger problem.  Often snapshots are taken of the 
map and downloaded to OSMand etc.  So even if  it was wrong for a week 
before being corrected the effects could linger through other systems.

Not exactly reassuring that they won't continue to change tags.

The clean up isn't the concern.  I can whip through the area with JOSM 
and slowly correct them as I have done with most of Niger.  HOT projects 
themselves typically cover a fairly small area.   Reverting might throw 
the baby out with the bathwater and there is little enough mapping in 
Niger as it is.

The concern is two fold, first one mapper who was working with me and 
mapping settlements and connecting highways got disheartened by the 
sheer number of incorrectly tagged highways and second and more 
important is prevention is cheaper than clean up.

These days to get to the instructions on a HOT project you need to say 
you want to map etc.  There is a certain amount of "phone menu 
purgatory" in extracting them.

I think most HOT projects refer to the African Highway wiki as I would 
expect.  This one seems recent and the concern is the instructions will 
be copied.

Cheerio John

Andy Townsend wrote on 5/9/2021 5:10 PM:
> On 09/05/2021 18:08, John Whelan via talk wrote:
>> On project 10645 the instructions are:
> First things first - Have you tried contacting the organiser of that 
> project?
> You might say "but it won't do any good".  However one thing that is 
> certain is that if you don't try and contact the organiser, they won't 
> know that there is a problem.
>> The concerns are first older mapping which has followed the Highway 
>> Tag Africa - OpenStreetMap Wiki 
>> <https://wiki.openstreetmap.org/wiki/Highway_Tag_Africa> have been 
>> retagged incorrectly.
> There are a few things that you can do to investigate this.  You can 
> try overpass queries with a date in an area to see if "highway=track" 
> goes up and other highway tags go down.
> Once you've identified a project giving poor advice, you can see who's 
> contributed to it, download changeset XML and see how many 
> "highway=track" there are in there.
> I can see that you've commented at 
> https://tasks.hotosm.org/projects/10645 .  I'd also suggest sending 
> the organiser an OSM message (or commenting on a changeset) so that 
> they definitely get a notification about your comment.  If they ignore 
> you, let the DWG know by email so that we can let them know that 
> someone's trying to get in touch.
>> Second how many other HOT projects have the same instructions?
> I've no idea; have you tried asking HOT if project text is 
> searchable?  This text doesn't seem to be trivially externally 
> searchable, though a quick sample does find more references to "please 
> refer to Highway Tag Africa" than the text that you mentioned.
>> Third how should it be cleaned up?
> What would really help would be if you could do a bit of investigation 
> of the scope of the problem, in terms of:
> * Project creators that don't know that they should be saying "follow 
> Highway Tag Africa"
> * Projects with incorrect text in the instructions
> * Incorrect data in OSM
> Once the size of the problem has been identified it'll be a lot easier 
> to decide the best way to fix it.  If it's just a few roads here and 
> there, then a manual process following a todolist in JOSM or elsewhere 
> will likely work fine.  If it's "everything by mapper X needs 
> reverting" then there are tools to do that.
> It may be that you don't currently know where to start with some of 
> these "find out the scale of the problem" ideas.  If that's the case, 
> please ask - perhaps on the help site.  Following a request from HOT, 
> with a DWG hat on I've been going through a process of tidying up some 
> overenthusiastic but undertrained corporate mappers over the last 
> month or so.  None of the things that I've been doing for that needed 
> access more than the same OSM API that everyone gets to use, though 
> some of the tools may be unfamiliar.
> It may well be that you'd like someone to help with data correction or 
> reverts.  Someone from HOT may be able to help with that; the DWG also 
> could.  However a request of the form "mappers A, B and C on projects 
> X, Y and Z have incorrectly converted $number of non-track roads to 
> highway-track in $country" is much more likely to be dealt with 
> quickly than "some mappers in Africa might be using the wrong tags".
> Best Regards,
> Andy (from the DWG)
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