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I'm interested in identifying the most common mapping errors you stumble upon from other OSMers (or that you make yourself).

If we could list some of the most common mistakes then we could use that information to drive improvements that may help to prevent the same mistakes being made in the future (e.g. by clarifying the wiki documentation, modifying the editor UI, writing scripts to find the mistakes etc).

This is obviously a very subjective question, but hopefully some people may find the answers useful. Please try to stick to definite actual errors, rather than simple differences of opinion.

This question is marked "community wiki".

asked 06 Oct '10, 15:01

GrahamS's gravatar image

accept rate: 28%

« previous123

Not identifying the different segments of a road properly

Often different segments of a given road are given different names. (Typically, the name of the road changes after a major junction or roundabout.)

But often the mapper does not break the road into segments, or provide the correct names to these segments.

This is a common mistake of a mapper who is tracing an uncharted area just using the Bing satellite image, but without much local knowledge.

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answered 13 Mar '15, 07:29

NarayanAras's gravatar image

accept rate: 0%

Sharing highway nodes with landuse

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answered 24 Feb '17, 12:43

Martin%20Borsje's gravatar image

Martin Borsje
accept rate: 0%

That's not a "mistake" since there is no consensus. Although many mapper discourage from joining ways with landuses.

(24 Feb '17, 15:21) scai ♦

From potlatch (users) I often have to fix self intersecting ways. Mostly this is a way going back again or making a small loop on itself before it ends or goes on. Not sure if this is a bug in Potlatch or if the users don't use it correctly.

At 348 km ways with 39.8 k nodes I had to clear ~90 of this errors.

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answered 24 Nov '12, 15:35

malenki's gravatar image

accept rate: 6%

This is perhaps part of the same problem as the "unjoined ways" problem. If people see the standard map tiles on osm.org as the "output" of their mapping rather than the data itself, then they won't think that self-intersecting ways are wrong.

As with unjoined ways, it's an education thing - once people have been told what's correct, they're more likely to do it right!

(09 Jan '13, 22:16) SomeoneElse ♦

Forgetting to add any tags to newly created nodes and ways !

I think this is a result of a combination of users mistakingly believing that they had deleted the untagged way or node, they didn't know at all that they created the node or way, a

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answered 10 Jan '13, 15:42

skorasaurus's gravatar image

accept rate: 12%

iD unfortunately makes it way too easy to do this. Potlatch 2 also lets you commit an untagged way without any sort of warning (in fact when I was still switching from iD to Potlatch 2 just to add parallel ways, and then switching back to do the rest of a dualize, I took advantage of this). JOSM will at least warn you, but how many newbie editors use JOSM?

(15 Dec '14, 07:02) skquinn

Deleting nodes whose tag's don't show up in Potlatch 2. I have seen situation where new users will "clean up" nodes whose tags are "Not recognised".

Hopefully this will be going away with the greater prominence of iD.

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answered 06 Jul '14, 13:58

InsertUser's gravatar image

accept rate: 19%

Some of the varied mistakes I've seen that I remember:

  • Stuffing ad copy in places where it isn't appropriate: note=* tag, changeset comments, or notes. I have nothing against marketing/PR/SEO people (in fact I've been one for a while) but there's a time and a place for everything.
  • Taking over a road segment or other object to add a business listing. As bad as ad copy may be, this is much worse and much harder to clean up.
  • Vandalism of the road layout, such as dragging a bunch of points together that clearly don't belong.
  • Putting any old garbage in opening_hours=*.
  • Putting incorrectly formatted phone numbers (not international format) in phone=*.
  • Abbreviating street names, whether mapping the actual road or in an address.
  • Various other address bloopers, like trying to stuff the whole street address in addr:housenumber=*.

Of course, I'm sure I'll see some completely new, weird, and not-so-wonderful mistake right after adding this.

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answered 15 Dec '14, 07:00

skquinn's gravatar image

accept rate: 0%

Sometimes users forget to mark that location which is most important for the people during travel like signs of hospitals, fire brigade and shopping complex. Hope you can understand the fact behind mapping.

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answered 08 Jul '14, 06:37

denygarcia's gravatar image

accept rate: 0%

edited 08 Jul '14, 10:42

SomeoneElse's gravatar image

SomeoneElse ♦


I would not classify this as mistake, people are not obliged to map. Contributing something that you consider not the most important thing is NOT a mistake.

(16 Jul '14, 23:41) Mateusz Koni...

By looking at the maps, very often for example residental areas are limited to go along the roads, even when area continues on the other side of road. Because areas have border lines, this adds unnecessary clutter to maps. Maps are easier to read when there is as little as possible unnecessary information.

So I suggest to combine multiple areas to one when they are side by side.

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answered 12 Aug '11, 21:54

PetriT's gravatar image

accept rate: 0%

This is a difficult one. Yes, you can combine areas if they are side by side and tagged identical. But having a road in between them means they are not side by side anymore. You may still combine landuse=residential, as the road is part of the residential area. You may not combine a lancover=grass, as a road clearly is not covered by grass.

(19 Aug '13, 15:47) Chaos99

One difficulty is when one side of the road is residential and the other side is commercial or industrial. There's no general rule bout if the road itself is residential or commercial/industrial, when it is both, so that road will be used directly to separate both.

Note also that parking amenities NEED to be connected to roads. When a parking is only connected on the side of the road (without necessarily hacing an internal service highway for a parking aisle), it is common to extend the parking up to the line of the highway.

(24 Feb '17, 13:48) verdy_p

Node sharing will then happen (it clutters less the map with too many nodes nearby when in fact any change on the topology of the road will also impact the topology of the parking. However, if there's a physical border separation between both (kerb, plantation) it's best to keep them separated using parallel lines, and joining only where the pavement connects the parking.

A remaining problem in ID is that you annot easily select alternate ways passing through the same nodes (there's still no CTRL+Click or Alt-Click to cycle the last selection, and still no way to select all objects using that segment or node, and no selection list where you can deselect the undesired objects, and still allow viewing what is in each object in the selection.

Such demixing is much easier to do in JOSM.

(24 Feb '17, 13:49) verdy_p

Missing bridges above (which I also up-voted), provided the answer to one of my questions: how to mark two intersecting one-way highways that do not permit turning from one to the other. In the acute angle case, than 135 degree and very difficult at 35mph (55km/hr). In the obtuse angle case, it would result in collisions at that speed or higher.

The answer: put a node at the intersection. I already had placed no turns permitted restrictions on the approaches to the intersection.

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answered 16 Mar '17, 01:37

OverThere's gravatar image

accept rate: 0%


Roadways and Railways should not use a connecting node where they cross. If it is a grade level crossing, you should tag a point on the roadway, but that point shouldn't be shared with the rail line. The grade level crossing is a feature of the road, not the rail. Another way to look at this is to tag the thing that changes -- the rail line is two continuous ribbons of steel, the road is broken as it crossed lines.

This also goes for power lines, pipe lines and administrative ways. If you want to have 'fun', look at the duplicate node map.

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answered 09 Oct '10, 12:42

gadget's gravatar image

accept rate: 0%

edited 09 Oct '10, 12:46


Hmm, you are mixing things. You can plot the level crossing before and after the real intersectin between the road and the railway if you like (although most of the contributors tag this once on the intersection itself). But you still have to put a common node between the two lines if they physically at the same level.

(09 Oct '10, 13:30) Pieren

Existing established practice in OpenStreetMap is to tag a node shared between the road and the rail ways. See http://wiki.openstreetmap.org/wiki/Tag:railway=level_crossing or use TagInfo (http://taginfo.openstreetmap.de/) to see what other mappers are already doing.

(09 Oct '10, 13:38) Jonathan Ben...

I agree that this answer in incorrect. Perhaps the confusion stems from looking at the U.S. data. There the situation is that the TIGER import brought in lots of road and rails which (probably) cross over/under eachother as bridge somehow, likewise lots of power cables which cross over the roads. Now the import brought in the geometries and annoyingly arranged it in OSM with two nodes sat on top of eachother. So not actually incorrectly connecting the two things, but creating a "duplicate node" (minor mistake). And then some people have been incorrectly "fixing" that by merging (major mistake)

(23 Feb '11, 13:23) Harry Wood

Actually, crossing nodes should be shared with the roadway, and it's a feature of both the road and the rail. Plus, there are some modes that can successfully navigate a turn from a highway to a railway. Track trucks come immediately to mind. And there's the hiker-lost-in-the-woods scenario where routing along a railway (legality issues aside) to the nearest highway or town would be quite beneficial.

(23 Feb '11, 22:28) Baloo Uriza

I vote down for this very bad suggestion. We need to identify eactly those intersections (if they intersect), or need to use distinct layers on ways (there's a missing bridge/tunnel section on the highway or railway).

So yes, create those nodes for level crossings (which are dangerous, and must be signaled as such).

This is the same case when there's a footway crossing a highway: we add crossing nodes as well, or when a highway crosses a river: we need a bridge or tunnel (different layers) or a ford node (actual crossing on the same layer)

(24 Feb '17, 13:51) verdy_p
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question asked: 06 Oct '10, 15:01

question was seen: 67,985 times

last updated: 20 Sep '20, 21:15

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