Thailand - Fix inconsistent bridge and tunnel tagging

Hello Thailand OSM community,

I am returning back with a new type of MapRoulette challenge: Thailand - Fix inconsistent bridge and tunnel tagging, which is based on specific spatial analysis that detected inconsistently tagged bridges and tunnels and we are hoping that it might bring value to improve the map.

Please note that the following cases might have triggered the inconsistencies:

  • Where highways are overlapping/crossing ways tagging ‘railways or ‘waterway’
  • Where highways tagging layers (…,-1,1,2,…) but no bridge/tunnel tagging is present.
  • Ways tagging ‘dam’ crossing roads, waterways with no bridge or tunnel tagging is present

Before adding tags, the editor should be able to validate his/her work using the recommended sources by the community. it is highly recommended that the editor applies local knowledge and expertise.

You will find more information on the challenge description and on our Thailand GitHub Page.

Please do not hesitate contacting me or leaving comments in the MapRoulette tasks.



This is again a task which certainly is fixing incorrect tagging, but I fail to understand why this is so high on your priority list.

Do you have any scenario where it is leading to problems? Routing should not care and most rendering will place water features below roads.

The point I would kindly ask you to pay special attention to are cases where the crossing also spans additional ways.

When looking at your tasks, I found this one:

This bridge also spans over a way. Here some additional check might be useful to confirm that really no road connection between the two exist.
In the above example, both ways share a node. This might hint that there is a connection. Aerial imagery give no clear picture but look like they might be connected.
You would need either better aerial or street-side imagery or GPS tracks connecting them to know for sure.

Hint: Google imagery would confirm they are actually connected, but we are not allowed to utilize this source: google streetview

Osmose detects significantly more of such untagged river crossings than your challenge. Roads crossing water without bridge is already detected 6500 times. Not considering the other issues you mentioned.

Thank you for your feedbacks, Stephan. We are aware of restriction for third party sources usages, just refer whatever we have in OSM and allowed to use. Users are welcome to use TomTom imagery in RoadRunner by the way.

The reason why we are fixing incorrect bridge and tunnel tagging is because these incorrect things do not align with OpenStreetMap wiki specification and impact TomTom product.

See a location where a road crossing another road tagged waterway:dam (OpenStreetMap)

As you can see the issue window on right side, no rule is logging on it but as far as I check Tag:waterway=dam - OpenStreetMap Wiki, it is not recommended to tag dam on highways like above situation.
This is not a situation that a highway and dam sharing a single way neither. Because imagery at 17.27164, 103.80700, dam does not exist.

(There is best practice on how to map a highway which is leading over the dam here Talk:Tag:waterway=dam - OpenStreetMap Wiki)
So there is no need to keep waterways:dam for this case and we will remove it.

Another situation is incorrect layer=* tagging.
Here is example of our finding that normal roads on ground crossing each other but the highlighted one got Layer=1 ,see OpenStreetMap

We checked Key:layer - OpenStreetMap Wiki and found that mostly bridge, tunnel, steps, elevators or other features (that have vertical relationships between crossing or overlapping features) will be tagged Layer=*. Other that these, there should be no layer tagging.

So in this case, we will remove Layer=1 from selected road even no OSM QA logging.

It is good that these thing does not cause problem in OSM. But due to different systems and platforms, TomTom considers these kinds of suspicious tagging/attributes as significant errors and that why are working on it.

If you have any priority errors on your mind, please feel free to let us know. We will bring your suggestions and discuss with team if we could fix it.

Best regards,

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thanks for this explanation. If it is an issue for your internal process, then it is fine to fix it. No worries about this.

I would prioritize issues based on how many people it potentially affects and how severe the impact is.
Broken routing on major highways is severe and can affect many users. That would be a high priority.
Same routing problem on a small residential road in a small village probably only affects the few people living there, resulting in low priority.
More “cosmetic” issues would be also lower priority for me.
The bridge/tunnel scenario would fall for me in this category. But as you explained: The priority can also depend on the impact on your internal process. That justifies a different priority ranking for you.

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