How to tag permanently submerged roads?

This summer we were misdirected through an artificial lake by my Garmin eTrex running maps.

I believe that the culprit is this way:

It is pretty nice that OSM contains traces of old roads on the bottom of a man-made lake but I don’t think they should be marked as highway=unclassified.

I don’t know how these kind of roads should be marked though. Should it be a seamark instead of a highway?

Is this water there permanent or intermittent?


Then I think this road is no longer a road (rather underwater artifact, let alone grade1…) and the part covered with water should be removed.

Do you know for sure that it’s permanent?

The changeset comment (10 months ago) reads

“Road submerged by the Riaño reservoir, frequently unsubmerged and in use”

Thanks for translating that.

I don’t know how frequent these roads are unsubmerged. My pictures were taken in the middle of the summer, august 2019. The water level was already several meters down from the high water level, but the road was unpassable (my kids are trying in the above picture…) BTW, access to this road was blocked by an electric fence.

There’s a similar road on the north side of the reservoir: . My GPS tried to steer me onto that one too.

I don’t want these roads to disappear, I just don’t want them to be used for routing.

Why, when your kids had so much fun? :wink:

If there’s a regular closure/opening schedule, this can be coded using the conditional: tag. I’ve asked Pablo Gutierrez on his changeset if he can clarify whether there is or not.

If there isn’t (as seems more likely) I will defer to more experienced mappers. Very tentative possibilities in my mind: tag as causeway=yes, with a description, as here. Or add a barrier node with access=no which would block routers while leaving the road in place, and those with local knowledge can use it. One could put a description in the barrier to that effect. Or even tag the whole length ford=yes, which would at least alert people to the possibility that it’s impassable.

But all of those break the on the ground rule, because it isn’t a causeway, isn’t a ford, and access=no isn’t really right, either: so we’d be ‘tagging for the renderer’, which is a no-no. Let’s see what others suggest.

EDIT: If one knew the lowest elevation of the road (and Spanish!) one could probably determine whether the road is open using this webpage here.

On two years’ data, it looks as if it could be seasonal:

EDIT2: the grey line is a 10-year average, so on that info, definitely seasonal.

Unrelated to the submerged aspect, it would seem that a barrier=fence node on the road should also keep a router from suggesting you travel that way.

I have seen several cases of fences that the part that blocks the road (public access way to a few properties) can be detached as is if there was a gate, but maybe then they should be tagged as barrier=gate :).

Yes I had thought of those, too:
And I agree, I’d call them gates.

They were actually quite angry and thus determined to try anyway. The alternative road to Boca de Huèrango wasn’t much fun, yet another 200m climb after a long day of cycling.

I’m very thankfull for all of you and your kind attention. As you may notice I’m an Openstreetmap novice. That’s why I asked for a solution instead of diving in myself.

I don’t know what’s the right way to fix this, but I do know that the present situation is wrong at least half the time (looking at the historical data; the water level at the beginning of august is the same as the water level at the beginning of february).

A barrier might work for this road, but as mentioned before, there are other similar roads in the same reservoir.

Top marks for their efforts: I hope I have children just as intrepid.

Personally I think coding the seasonal access is a good move, perhaps erring on the side of caution with the dates. I’ve emailed León tourist info, so we can see what they come back with if Pablo Gutierrez isn’t a local.

That’s assuming the routers can read such conditional access: do you know?
Do they ever display hazard warnings if these are coded in the map, too?

Interesting case, bdr! I have cycled there last year (no, not on that submerged road) and camped at Boca. Really can’t imagine it will be in use, I guess only after very long drought? Since you mentioned a fence I should tag this as barrier=gate and block the submerged parts with access=no. I also doubt unclassified is good, service would be better, or maybe even highway=disused (like railways). About conditional access you can think of access:conditional=yes@(seasonal) with seasonal=yes (I dont know when this road is open, maybe only a note is better). Access:conditional is a tag that most routers can’t read. The OFM uses this in some cases but it will be difficult to handle, so if this road is generally closed I would suggest access=no. Ford=seasonal is also a good tag you can use in combination with seasonal=… The OFM will mark this with a submerged icon so the user will see that.

On google maps you can see this road when it is unsubmerged: and
Looks more like a highway=track.

I would tag this with
access:conditional=yes@(seasonal:dry_period) and maybe

BTW On youtube it seems an asphalt road:

Gleanings from YouTube comments tending to support “access=no”:

In the comments on ligfietser’s video, someone said they were on the bridge at Pedrosa in August 2 years ago. But the video itself appears to show someone driving down to the water and then returning by the same route, not crossing the valley, as a wag points out in the comments.

Here a pilot shows the bridge was passable at what he quotes as reservoir water level of 37%, again 2 years ago: Someone comments that “This shows the drought we had this year”.

By the by, the bridge itself seems quite interesting: Roman, and on the Lista Roja (Red List) of endangered monuments run by Hispania Nostra.

I happened to cycle into such a submerged road else where, but it already had the reference number of “submerged”:

I agree with access=no because most (or almost all) of the time is submerged.

The video shows someone driving from Boca de Huérgano towards old Riaño, still submerged. On the way back the car turns right at 8:10. At 10:10 the car is at same position as my picture on top of the thread, facing the other way.

Having seen this video I’m less thrilled about my kids trying to ford the lake. I didn’t realise there was a deep river bed at the bottom.