Imaginary fords

  • There are many trails crossing a small dry gulch (a waterway, intermittent=yes) tagged as a ford. While I’m sure there are some intermittent streams that get intermittently large enough to have a ford, the ones in my example area below do not qualify as a ford. Water is only in these gullies in the middle of a very large rainstorm, & even then most of these would be jumpable. This may be a somewhat local, or western US problem because we have a very inclusive NHD waterway import, so many dry gulches show up in OSM. Many of these probably should be ephemeral, but that seems to have been rejected.
  • OSM carto marks these with a ford icon
  • JOSM flags these with warnings, crossing highway/waterway, which encourages this bad tagging.

For example If you look here with Carto or Tracetrack Topo, you see a very large number of fords in this area.

This is a dry area and I can assure you there are not any fords here.

I’m hoping to have some consensus here that not every road or trail crossing an ‘intermittent’ stream is a ford.
I’d like to see JOSM change the validator so there is no warning for an intermittent stream crossing a road or trail.
If we’re going to keep these bogus fords in the database then carto & tracetrack topo should not show them. In general a user wants to know where the fords are and this is just noise.


I think the best solution here is to have the path and the waterway intersect but not tag the node as a ford.


I’m not sure I entirely agree with the statement “every road or trail crossing an ‘intermittent’ stream is not a ford”. I think it depends how intermittent the stream actually is, since intermittent=yes covers everything from “once a decade” to “nine months per year”. For instance, I’ve been hiking here a few times: Node: 1350996457 | OpenStreetMap, and I would guess that the stream is probably running from the first rain in fall until well into spring/summer. It then completely dries as the summer goes on, with strong year-to-year variations in timing: fairly typical stream behavior for Southern California. Every time I’ve happened to be there, there has been a ford with stepping stones/logs to cross. I think it’s useful information for a user to know that there is at least sometimes a ford that needs to be crossed here, and the intermittent=yes on the stream indicates that water might not always be an obstacle.

You seem to have more ‘ephemeral’ streams in mind, which only carry water immediately after relatively rare rainstorms and drain very quickly. For those, that is, cases where it would be highly exceptional for a hiker/road user to encounter a ford, I think omitting the tag is fine. But for the case above, where a typical user may well see a ford there, it seems extreme to say such a tagging is impossible/bogus. I certainly have not imagined crossing the stream at the node above!


That was a typo on my part, I meant, ‘not every road or trail crossing an ‘intermittent’ stream is a ford.’ I fixed my post. There are some, such as your example, but in my region, someone has decided that they all are. We’re probably in agreement here.

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Funny you should post this just now. I was just joking with @watmildon about untouched TIGER roads and original NHD waterway imports where someone has added “fords” at every intersection because the validator told them to.

At the very least, people should make sure the highway and waterway are in the right place before deciding what to do when they intersect.

But I also agree with the premise that there are highway and waterway intersections where no “ford” is needed.


When an intermittent stream happens to run, however unusual that is, would a ford materialize at that point? There are 11,309 occurrences of ford=* intermittent=* (mostly on nodes) and 1,363 occurrences of ford=intermittent (mostly on ways) that suggest this possibility. iD’s Ford preset also has a field for seasonal=yes.

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In OSM speak a ford is just the point at which a waterway passes over a highway. What you seem to be concerned with is how Carto chooses to render these.

What is being suggested here sounds a bit like Tagging for the renderer - OpenStreetMap Wiki

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This is a real deficiency in current tagging practice. We should have a few different values for such a broad range of intermittency. Water most of the year, no water most of the year, and no water most years all seem like quite distinct situations to me.

This seems reasonable.

This is what the wiki says, but I’ve never thought that such a simple definition is useful. A ford is a feature worth indicating on a map because you will need to be prepared to wade through water, have a high enough clearance vehicle, or similar. A crossing where a stream is so small that it can be stepped over is not called a ford and it is not helpful to indicate it as a ford on a map. Similarly where a waterway is nearly always dry but flash floods are possible, a crossing would be called flood prone, not a ford.


A couple years ago, there was a proposal to introduce water_crossing_level:foot=* to characterize the difficulty of a ford based on water depth in general terms.

I think it’d be helpful to indicate it as something on a map. Kind of like ford=stepping_stones, it implies needing a certain amount of mobility, and could be an obstacle to some who otherwise might want to take that path.

I don’t think there’s currently a good documented way for tagging a waterway crossing that a typical adult on foot could jump, and I don’t think that’s what a map user should be assuming for a waterway crossing a path at an untagged node.

I’ll certainly agree that there’s room for Carto to improve how it shows different types of fords, but I’m sure everyone has their own pet peeves with things they think it should do differently. :slight_smile:

For sure there are intermittent/seasonal fords. I haven’t seen the intermittent tag added to any fords, but that could be useful. Many of the cases I’m looking at wouldn’t qualify as a ford anytime in recent history.

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It’s tagging to be useful. A user might want to know when there is a ford. If the database has 95% false fords (where you or your vehicle don’t get wet unless its raing) and 5% real fords, it isn’t very useful.


stepping_stones makes sense (for foot travel anyway) if there are some. If one needs to jump over, maybe that’s a ford.
I’m merely pointing out that this is not a ford:

The photo is a typical highway=path, crossing a waterway=stream, intermittent=yes.


If it’s a ford some of the time (whenever the stream is there), then I think it should just be tagged as an intermittent ford as previously suggested

And if it’s never a ford, then probably the stream shouldn’t be there either.

And separately from those, it’d be nice if maps rendering ford=yes also did something reasonable with intermittent=yes to make it clear to users that there might not be anything there, and it’d be nice if there were a good way to distinguish between intermittent meaning “once a decade” and “nine months per year”.

And for the “once a decade” end of things, I wonder if it should be mapped as a waterway at all, or if it is maybe should have some kind of lifecycle prefix so that it doesn’t show up “normally” at all?


That might be the case most of the time, though there might be a heavy rain and it turns into a river. As a hiker/biker I would be still interested, that there is a crossing of a potential waterway. On top of that I would like to have information’s regarding under which circumstances I might need to cross a ford.

So instead of reducing the level of detail in OSM, I would prefer to add more details. :wink:


Not quite sure, whether it’s a good assumption. Recently there have been a lot of “nevver happend in the century before” :frowning:

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I would expect your “ford” to be rendered different than my ford:

but I would prefer to have the information in OSM, that under certain circumstances there might be a ford, which I need to cross. Though since waterway=stream is defined as I can step over, rendering fords on streams should be different than fords on rivers anyhow. But also OSM has plenty of streams you can’t step over. :wink:

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This is one of the reasons I stopped bothering about osmose. Due to detailing backwoods paths I amassed such a large number of missing fords, where there is a waterway in the (imported) data but no waterway on the ground so I did not map a ford there – Thankfully, editor validator tips clickers relieve me of this QA burden.

PS: Still I do not like the prominent rendering of fords where there are none. Somehow validators make the tag less useful.


I would not blame the qa tool. It’s rather a lack in our data. A simple boolean is not able to describe all the variations a ford can have. Even if you exclude imaginary fords.

Mapping things that are variable and can change is always a hassle and the water refuses to stay in the same place.