I have now found evidence that user VLD006 1 year ago has deleted roads and a bridge that I added a year earlier. Check out https://www.openstreetmap.org/way/436489101/history.

Here are my GPS tracks:


New roads (at the time) are shown in red. You can see in the bottom right that it crosses the canal. That and the adjacent piece are now missing.

Vandalism? Incompetence? Time to mass-revert?

Hi Beddhist,

I apologize for this data error that one of our editors caused. He is not with us anymore so I can only make assumptions on his reasoning. Looking at DG Premium the connection is less obvious and the bridge did not exist yet so i assume he thought it was a mistaken connection. However, in DG Standard or the GPS traces you added the connections can be confirmed as legitimate and the user should have checked both.

Regardless, changing community data like that is not our policy and we try to have as light a hand as possible with it. We assume the community members have the most context and up to date knowledge of the situation so we avoid altering the pre existing data to the best of our ability.

We are putting a ton of data onto the map, the Thailand road network has more than doubled in number since we started, and our editors are only human. We will inevitably make mistakes, but we are committed to cleaning up anything we get wrong the first time. Our team is passionate about the project and they want to make the best map possible, just like everyone here.

I have corrected the geometry of the road in question. Please feel free to post here or comment on any other changesets you might find that are not up to standard. Thanks for bringing it to our attention.


Hi Jeff,

Thank you for the feedback. There are several points that need addressing here:

In the areas where I have looked most of that appears to be private driveways and farm tracks mapped as residential or unclassified. At the very least anything shorter than about 400 m should be either reverted or marked as track. I was a passenger on these roads yesterday and observing my GPS about every other road we drove past didn’t exist. There is no way I can flag or correct all of them. Heck, even as a passenger I cannot set waypoints fast enough.

Roads should never be deleted by armchair mappers, no matter what you see in aerial images. Anything that has a source tag should only be deleted or modified after verification on the ground. I think that is common sense.

We need to remember that what we do in this project has a real-life impact on the people who want to use these maps. It can make the difference between getting to your destination efficiently, or having your day spoilt. OSM in the Thai countryside used to be far more accurate than Google Maps or even ESRI’s GPS maps you have to pay for. I am no longer confident that this is still the case.

I have no idea what your project has done to OSM in other countries. For Thailand I would say: revert all changes and start over, with functioning QA. Then perhaps we could persuade some of the old hands who have left in disgust to come back.

For me this is crunch time. I was pissed off when a while back OSM legal beagles had them delete a large chunk of data, just to change the licence. I got over that and moved on. This is far more serious. The overall quality of the map data is in question. I’m sitting on 2 years’ worth of tracks from Captain Slash that I was meaning to map. I’m holding back on this for now and if it doesn’t get resolved satisfactorily I, too, will vote with my keyboard.

Kind regards,

I’m trying to make some videos about my concerns. Very boring and crude, sorry.



I’m trying to make some videos about my concerns. Very boring and crude, sorry.



Hi Tom,

Funny you picked road 2243 in your 2nd vid: it’s one of my early ones, probably laid down with the old GPS V on a blank canvas, so the accuracy may not have been too great and there was no hi-res imagery available at the time. We can, however, take the original trace of that road as a GPS track, probably as accurate as the other one that is there, which looks like made with a bicycle.

Now let’s move 5 junctions North and we come to this village under a cloud in Bing and DG Premium:

Switch to DG Standard and an unholy mess appears:

The main road badly needs correcting here. It seems clear that the FB user has used the DGS image for drawing, where clouds have obscured the Premium images. As you move S and E the discrepancy between the two increases. Which is correct? Without more traces it’s almost impossible to know. But the point is, the smaller roads cross here straight over the main road, not with a zig-zag as shown and with an additional 3 nodes the whole junction can be improved a lot.

Further, Bing Maps clearly shows the road heading E as Rural Road 4012, so can mark it as such. I don’t think we can say for sure whether any of these roads are sealed or not without going to Google Maps, which we are not allowed to do.

Now, let’s move further N again, just past the crossing of roads 2256 & 2243:

What happened here? Clearly, either the main roads are in the wrong place, or the two minor ones. Switching to DGP it becomes clear:

The mapper has used the DGP image to draw these two minor roads and ignored the image offset. There is clearly a break in the image on the main road, half way to the junction with the minor road. But it doesn’t extend due W, it curves SW, missing the minor road. So which one is correct? We don’t have a source tag for Rd 2357, but the GPS traces and main roads line up better with the DGS images, so I think we should use them. Both these roads need to be moved, the junctions lined up and the T junction with road 2256 needs to be cleaned up. Then, of course, we need to continue along the main roads in all directions and rinse and repeat.

This isn’t rocket science, but it does require to engage eyes and brain. If an organisation wants to mass-edit, then there is a learning curve for all involved and some initial hand-holding and reviewing of edits.

Via a mapper’s profile I have found the wiki page for the FB project: https://wiki.openstreetmap.org/wiki/AI-Assisted_Road_Tracing
That reads all very well, but where is the community engagement? Where is the QA?

You have added 150,000 km of roads. Most of that will have to be corrected. Where do we find the manpower to do that?

Hi Beddhist,

The road in your first two frames is my next video project. If you want to fix it, please let me know. I also noticed the offset, it’s pretty confusing.

I hope you understand that I am never complaining about OSM mappers who worked with about nothing in the past. I do think FB should be able to do better given all their resources now. But they don’t.

BTW, I also prefer to bicycle.

Best Wishes, Tom

No, I’m not touching that one, so that the folks from FB and the data working group will have something to look at. So I suggest you don’t edit it, either, for now.

And yes, we are on the same page here. I was merely trying to explain what is what, i.e. there is the GPS track and the road is also created from a somewhat crude GPS track log, as opposed to roads drawn from imagery.

I have just gone through “our” village and looked at about 12 FB residential roads. I had to edit every single one, as most of them are either private driveways and/or unpaved. On the other hand, in the open fields they have drawn many tracks that seem pretty good. It’s the roads in built-up areas that we seem to have the most problems with. That’s why I’m suggesting that everything shorter than 2-400 m be reverted, as well as any deletions they have done.

I have emailed the DWG, but no response so far.

Kind regards,

I have found and uploaded my GPS track for road 2243.

What I predicted would happen today happened to me, twice: I got facebookstreetmapped. A residential road that in reality was a track so small, my wife would not let me ride my bike through. The other end was private property, it seems. Had they used DGS instead of premium it was crystal clear what this was.

I have seen zero response from the DWG, I could not find a single email in the import mailing list; it looks as if we are yelling into emptiness.

I am now suspending any further activity in OSM in the faint hope that this may get resolved. Perhaps this will be the second time I will port all my data to another project.

Good night.

Tom, Dave, Russ and others in Chiang Mai I might forgot to mention. Shall we meet somewhere mid to end of the coming week? We could discuss above what the worst problems are and how to address this with Facebook’s editing team.

Also problems with regards to quantity. I am certain we find exceptions for every rule thinkable, but if there is a systematic problem we should address it.

Good idea, Stephan. Too bad it’s too far away for me.

I have received a reply from Frederik Ramm of DWG:

They are well aware of the issue, but are unable to act, unless

He suggests we get together and work out exactly what we see as problems and how we want FB to address them.

There are now several forum topics dealing with this problem. May I suggest one is chosen and stickied?

From where I am sitting I can’t tell what FB are now doing. Are they continuing as before, have they stopped? Everything I have dealt with so far is about a year old already.

The problems I have seen so far:

  1. Ways mis-aligned, probably due to lack of GPS tracks and/or reliance on single imagery.
  2. Lots of private driveways mapped as residential. (Should we even map such driveways at all?)
  3. The tracks vs. roads and paved vs. unpaved issue. We need to sort this out as a group once and for all.
  4. Massive amount of data already imported that needs reviewing/fixing/deleting.

The ball is now in our court.

Kind regards,

OK, following a personal email from Stephan I’ll attend any meeting with a view to moving forward. I hope that if the Thai mappers can come up with a clear set of instructions to the DWG, maybe we make can some progress.

Everything Tom & Peter say comes from the same heart as me … when we map, its as a human, looking logically at the road network. This is what dedicated OSM mappers like us did … see something wrong, or something that was missing with every new set of aerials … we added it. Smooth a curve here, straighten a road there … continual improvement. The FB team just banged it in, and moved on. Eventually the sheer volume of “tidying” FB inputs was just too much … we never stood a chance.

I note we are being self critical over our local definition of road vs. track … Peter is right… if in doubt, downgrade it, and revert later when better evidence comes to light.
My biggest issue with FB is that clearly they do little to correct the existing map when they import … you know it makes sense if, when you draw a road, take a quick look at the adjacent roads and see if with a few more additions, navigation would make sense, and through routes would be created.
I have always criticised FB from this angle, and once you see a nest of FB imports, there is a tendency to move on … its heartbreaking to see it, and a waste of time to start editing it.

And by way of a real example, I was driving down to Kanchanaburi last week, and noticed a lot of U-turns missing on Hwy 340. I know that in the early days, the aerials were poor and a lot got missed, but in Thailand, passing the road you need and doing a U-turn is fundamental part of the driving here. I vowed to correct on my return…

Oh yes, Facebook got there first, and I thought, well lets just log what “sloppy” mapping I notice, and it didn’t take long to fill a page:

Chai Nat :
Way: 527960964 - VLD007 added many residential roads either side of the Trunk Hwy but completely ignored the link roads (U-turns) that are necessary to turn into them.
Way: 528184019 - VLD007 draws a long road as a residential despite fact its clearly unpaved, and only passes one farm, but then fails to draw the bridge at the eastern end. This should be a track, or at the very least, get an unpaved tag.
Way: 527984298 - Ditto the above, but it doesn’t even pass a single structure once leaving the asphalt road.
Way: 527960922 - The residential road is drawn, but then no attempt has been made to clean up the poorly drawn junction it connects to… the one with the fixme=precision tag clearly visible. Its also unpaved, but no tag was added.
Way: 527963823 - Does the road really need this many nodes in the curved area ? It can’t be like this in real life? I would smooth out, deleting surplus nodes.
Way: 527960904 - The way connects to Hwy 340 Eastbound carriageway, but not the Westbound when clearly there is a U-turn gap in the median to do this.
Way: 527922341 - Again, Im guessing FB automated software picked up the residential road, and VDL007 connected it to the Southbound carriageway. There is a U-turn link that connects it to the Northbound but he was either too lazy or simply blind and did not draw in the link. Its errors like this that makes GPS navigation useless.

It’s just the whole “bang it in attitude”; roads are split in random places, ever heard of the merge command, FB ? And crossroads are a rarity to them … take a look at the number of residential roads where the connection is clearly a crossroads in reality, but FB just goes with wherever their automated system puts the node… even if its is only 5 mtrs offset. So whats the issue ? I’ll tell you, my GPS says “turn right, then turn left” and then I’m heading down the wrong road. But then they never ride here, and with a “successful OSM project finished” on their resume, off they head to another posting.

And so with heavy heart, they say “we are really concerned, but VDL whatever has left us now” … OK, if he was that bad, revert every one of his edits. Some of these date to 2017, so clearly going back and putting things right doesn’t seem to be working. Few changes are taking place.

And while I’m on the subject, ask VLD012 why he changed Way 383032616 from track to unclassified road (without even adding the unpaved tag). The imagery shows this goes through a forest, is unpaved, and runs steeply through terraced rice paddies. Chris labelled it a track for a reason, and I humbly apologise if VDL visited and its been asphalted since … but go on, prove me wrong. We don’t change existing data they say … more meaningless words.

The way forward … well I cant make bulk changes, I dont have the skills, but we should start taking control of the Thai map back … lets downgrade the short roads as Peter suggests, lets convert FB residentials to unpaved alley, until we can verify differently… lets convert all FB import=yes residential roads in the countryside, to unpaved.

When I started complaining about FB, I was a lone voice … I see Tom & Peter now following suit. Frederick of the DWG is correct; we never gave them any clear indications of what was wrong and what to do. As Thai mappers, we should meet and at least see if we reach a unanimous way forward.

We can do this, if we want to … lets not stand by and do nothing. You know, maybe we don’t even need the DWG involvement. I’m sure they will be happy if we make our own corrections locally. I certainly don’t think speaking to FB is any good, given the poor responses to date … it OUR BABY I’m afraid.

Rgds, Russ.

Thank you Russ, I think we are on the same page, except for one thing: I don’t think the DWG want to get involved. Like I said, the ball is in our court and it’s up to us to come to a consensus and then deal with FB directly. At least that’s what I take from Frederik’s email.

Perhaps we are a bit hard on FB: they may not have the resources (or experience) to fix existing roads much. I think if we could get them to stop mapping private driveways and mark most small stuff as tracks then we have a more detailed map that is then relatively easy to improve upon.

I still believe that a mass edit is called for.

Please keep me in the loop with a CM meeting. Perhaps I can swing a trip North.


Not exactly; but it’s difficult to get involved when there aren’t specific problems being pointed out in a form that we can do anything with. For example, above Russ has said " ask VLD012 why he changed Way 383032616 from track to unclassified road (without even adding the unpaved tag). …". That’s a good question - why hasn’t anyone asked them yet? The actual changeset I suspect is https://www.openstreetmap.org/changeset/55696040 ; there are no comments in the discussion. In fact, no-one has commented on any of that user’s changesets at all: http://resultmaps.neis-one.org/osm-discussion-comments?uid=6271594 .

Without details of the mismapped features that make up the “Facebook problem” there’s little that’s actionable from a DWG perspective - we can’t say “the local community asked you to do X, you’ve done Y, and we know that because here’s another changeset discussion where the local community have said that you’ve done Y again”.

Best Regards,

Andy (from the DWG)

Andy, that process is not going to work. We need to keep the discussion in one place. That’s why I proposed above to stick one forum topic. If we try to discuss every changeset individually then we will get nowhere.

We are talking about multiple users, thousands of edits over more than a year. The main problem is roads having been created that should either not be there or should be tracks. We also see imagery offsets .

All of this data, 150,000 km of it, needs to be reviewed, individually. Only FB would have the resources to do that. I am willing to do my bit and train one or two of their mappers.

Failing that the only viable alternative is to revert all their edits, as some of us here consider the map now polluted.

I do believe that some of their contributions are valid and valuable.

Let’s see what happens at the CM meeting.


If you want to limit the discussion to people who happen to be following this subforum then fine, but you can’t then say “I don’t think the DWG want to get involved” (for completeness, it was me that created the forum thread https://forum.openstreetmap.org/viewtopic.php?id=57387 in the first place as a heads-up to local mappers).

There’s always going to be discussion about “quality vs quantity” in OSM (there are lots of ongoing discussions about that right now on various OSM lists and in forums and chats), but without specific examples of specific problems there’s not a lot we can do. Rants on the forum certainly give a feeling of the scale of the problem, but they’re not really actionable. Right now there are about a dozen actual reported issues in OSM in the DWG queue, where someone has said “X is wrong because Y”. DWG members can either deal with those in whatever free time presents itself, or they can trawl through forum (and mailing list, and help question, and chat) threads looking for potential issues. Please help us to help you.

Also, let’s not forget about the QA done by mappers around the world in places that aren’t local to that area. Examples include geometrical impossibilities, tag misspellings etc - see for example http://resultmaps.neis-one.org/osm-discussion-comments?uid=5314378 . Changeset discussion comments are very useful to people doing that as they often indicate whether a problem is already known about and whether it has been acknowledged by its author.

Let’s meet. I personally mailed to the mappers in Chiang Mai I know. Posting it here for the (likely) case I missed someone.

Thursday 11th October, from 11:30 onwards, Shewe cafe

For planning, please let me know if you plan to attend so I can arrange with the shop.

@Peter: Skype?

Thanks Stephan, I can make it, as I have to be in Phayao on the 14th. Count me in.

As mentioned elsewhere, I’ll attend.