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
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.
answered 16 Mar, 01:37
Sharing highway nodes with landuse
answered 24 Feb, 12:43
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.
answered 13 Mar '15, 07:29
To draw a building shape, the mapper traces its terrace, but does not move it to its base
This "parallax error" is an extremely common mistake in drawing shapes for highrises.
The mapper uses the Bing satellite image, and traces out the top of the building.
But he forgets that the satellite image is not exactly "top-down", about 15 degrees angle to the vertical. Thus the base of the building does not lie exactly under its top. In fact, the taller the building, the more this offset!
On the other hand, all map features having low heights are traced without such parallax errors. For example, roads, boundary walls, low-rise buildings.
As a result, many tall buildings appear to be shifted from their actual positions. Some even touch (or "crash into"!) the adjoining areas.
answered 13 Mar '15, 07:20
Confusion between "Common Name" and "Operator" of a POI
For example, take a Citibank ATM.
Another example: A Dominos pizza joint. Legally, "Dominos" is the brand, operated by a local franchisee (a separate business entity). So how to fill these attributes?
As a result, I have seen inconsistent entries in POIs.
Suggested solution: The mapping tools (iD/Potlatch) should have more explicit tooltips.
answered 13 Mar '15, 07:03
Some of the varied mistakes I've seen that I remember:
Of course, I'm sure I'll see some completely new, weird, and not-so-wonderful mistake right after adding this.
answered 15 Dec '14, 07:00
In Africa highway mapping, track only goes to farmland.
So ruled in Highway_Tag_Africa.
"The road conditions in African countries do not always correspond to their economic and social role. A road typology should be based on the road importance and not on the surface or the visual appearance of a road."
This means, it may look like a track but, if it goes from a major road to a hamlet, it's an unclassified highway, except a 4x4 can't drive it because it wiggles too much (then it's a path). Ditto from hamlet to hamlet.
People new to Africa mapping always get this wrong.
answered 13 Dec '14, 14:51
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.
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.
answered 06 Jul '14, 13:58
Using search-and-replace to do small 'mass edits'
New users tend to use the search-and-replace function of editors to do 'corrections' to a massive amount of nodes or ways in their area when they believe they found an 'error' of some kind.
Not mentioning here if the 'error' really is one or not (new users might have trouble understanding all the tagging schemes used in OSM), the mere application of such changes in an automated manner often destroys more valuable data than it fixes. This is also regularly used to fill in perceived "blanks", even if those blanks are left intentionally or are coverde by some kind of default.
This is often combined with the "leave no changeset comment" problem already mentioned.
answered 19 Aug '13, 16:02