NOTICE: is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum


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%

« previous123next »

Combine two highways because they have the same name, ...

but the two ways actually have different tags or are not both members of the same relation.

permanent link

answered 14 Aug '12, 18:42

cartinus's gravatar image

accept rate: 27%

Users are generally not faulty, they just trust what the common editors allow them to do without warning them.

Merging ways with distinct tags or not members of the same sets of relations should open a conflict resolution editor allowing to see the differences and accept merging tags, or reject it (notably for distinct relations, these relations need to be merged separately if needed, using the same checks on tags and sets of parent relations)

The same remak applies when splitting ways (here also the parent relations need to be all updated in their lists of members), but most often it is simple to repair if a relation is forgotten.

(24 Feb '17, 13:25) verdy_p

In JOSM, the set of parent relations is not automatically loaded for all ways when merging or splitting them: but JOSM still does not automatically download the parent relations. You have to do it just before merging/splitting ways, pressing CTRL+ALT+D.

However the data server frequently returns 5xx errors when looking for parents (this error isn't reported by dialog or notification on the screen: you see it only on the console, provided that JOSM is launched from a command line window to see it, or by enabling the console window in the Java config menu. Unfortunately, if you close that window, there's no way to reopen it. Suggest JOSM to add an panel to show what is sent to the std-output.

If the server returns an error, nothing happens in the editor, users may feel that all parents are loaded, when they are not. The work around (if you see this error), is to zoom in on a tiny area around the node of the way to split or connecting ways to merge, and then download all objects in that area: the OSM server does not fail downloading all parents of these ways, when it fails by querying only the lists of parents and loading them: this is still a bug/performance issue on OSM server!

(24 Feb '17, 13:28) verdy_p

In the ID editor, there's a separate old unsolved issue, which occurs when splitting ways that are members of relations: the newly created way is just added at an inaccurate position at end of the list of members, instead of being inserted immediately before or after (depending on the connection of the other end nodes with other members before or after that way).

This creates havoc in many relations that expect a correct ordering, and complicates a lot the reparations that could be done later when the geometry needs to be repaired (not just for closed rings in multipolygons, but as well for linear objects such as associatedStreets/rivers...).

ID should preserve the continuity of member ways as much as possible, and when splitting ways, it is evident that both parts should NEVER be separated in the list of members.

(24 Feb '17, 13:29) verdy_p

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.

permanent link

answered 13 Mar '15, 07:29

NarayanAras's gravatar image

accept rate: 0%

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.

permanent link

answered 13 Mar '15, 07:20

NarayanAras's gravatar image

accept rate: 0%

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

permanent link

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

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.

permanent link

answered 15 Dec '14, 07:00

skquinn's gravatar image

accept rate: 0%

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.

permanent link

answered 13 Dec '14, 14:51

rwst's gravatar image

accept rate: 0%


That's not so different from other countries. The highway tag should be used to tag the road classification, not the road's look.

(13 Dec '14, 17:13) scai ♦

Not Mapping!

The most common mistake users make, is to register for OpenStreetMap, but then fail to do any map editing at all. Strange but true! See pascal's „Nominal Members“ of OSM? blog post.

Please all you people. Have a go at mapping! Make mistakes. We don't mind.

permanent link

answered 06 Oct '10, 17:03

Harry%20Wood's gravatar image

Harry Wood
accept rate: 14%

edited 07 Oct '10, 09:47

GrahamS's gravatar image



Absolutely Harry. I'm keeping a careful eye on this post because I definitely don't want it to turn into a set of "slag off the noobs" answers. I'm interested in finding where the common problems are so we can help the noobs (and everyone else).

(06 Oct '10, 17:21) GrahamS

As a new user who's registered but not (yet) edited the map, I'll suggest that some sort of introduction to editing the map is desperately needed. Or if there is one, it needs to be much more prominent; I found my way to this "help centre" looking for such a guide, and still haven't found one. I'll be glad to have a go at mapping once I figure out how!

(13 May '11, 19:17) cmadler

Update: Via the blog post linked above, I found my way finally to the Beginners' guide, but I'll suggest that it should be much easier to find!

(13 May '11, 19:27) cmadler

I'm not surprised that MANY people sign up then give up. The instructions and answers are spread over many different systems and I haven't found answers to some pretty basic questions yet. I had to create a second login to post this comment and more logins are required to participate in discussion groups. I tried watching a video, but it's just too large for my rural connection. I am very discouraged at this point. I edited databases from '75 to '88 and continued with systems design work until '01 but I'm not sure that I can find out how to help here.

(22 Oct '12, 00:55) etch-a-map

Absolutely agreed re "The instructions and answers are spread over many different systems". While things are getting better (this help site didn't exist when I started, for example) there's still a long way to go.

One of the places that I'd suggest asking "what's it all about then" questions is the "newbies" list. It's relatively low traffic, so if you subscribe you won't get swamped.

Another is the "#OSM" IRC channel. There's a wide range of different discussions in there at any one time but if you ask a question like "how do I do X?" or "I've just mapped Y, does it look OK?" someone will usually be around to reply (if you don't have an IRC client installed you can just use the web client).

There are also various diferent discussion groups within the forum, and for a general "contact" overview see this page.

(22 Oct '12, 09:07) SomeoneElse ♦

Go mapping!

Yes, but don't map ignoring the licence and contributor terms. Mapping from Google is wrong but there are lots of allowed sources (including the Bing imagery covering the world by satellite in medium resolution, plus US and most of Europe in high resolution Aerial orthophotography). But let's not forget that Bing imagery is frequently old (often more than 5 years, and even the last monthly updates in Bing are photos dating almost one year). But DON'T REMOVE data you don't understand or that you don't like rendered because it's "ugly" for your eyes or invisible in Bing images!

(27 Nov '12, 10:14) Verdy_p

Another reason for people not feeling brave enough to start is that the default editor which comes up when I click 'Edit' is Potlatch 2, but the online tutorial I was sent a link to when I signed up shows a different or older editor, bearing little visual resemblance to Potlatch 2. Also, no warning was given that the Bing imagery is not necessarily exactly aligned. I merrily set to work adjusting local buildings and roads by 2 or 3 metres wondering why so many were a bit out.

(02 May '13, 16:13) Jonga

What's the URL of the online tutorial that you were sent so that we can get it changed?

(02 May '13, 16:17) SomeoneElse ♦

I'm a newbie. I'll say that although there is definitely available documentation it is very confusing to have docs for iD, P2, JSOM all mixed together. Also, I didn't find any that are comprehensive from a beginners perspective, they include how to add a POI but tagging that POI is covered in a very high level gloss. For example, I am trying to figure out (please don't feel the need to answer here, I've already asked in the forum...) how to add a golf=driving_range tag but can't to find specifics. iD only offers me some of the tag options and I'm not sure where to put it in P2 or JOSM.

(30 Aug '13, 20:32) jaseiny

Hello, I registered today since I am using OSM heavily on my ANDROID phone during my trip in Japan and intend to contribute. Looking for a tutorial, I came here. Here a good tutorial on creating OSM maps: including the following links: This should save you at least 30 minutes of searching around for tutorials, beginners guides, OSM basics, etc.....

(23 Aug '14, 04:22) ostino
showing 5 of 10 show 5 more comments

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.

permanent link

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...

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.

permanent link

answered 06 Jul '14, 13:58

InsertUser's gravatar image

accept rate: 19%


Unconnected Ways

Screengrab from Potlatch editor showing unconnected ways

The selected way is a residential street that should clearly form a junction with the "Langdon Road" way at the bottom of the image. But as you can see, there is no black box around that point, so the original OSMer has actually missed and the result is that the way stops just before it gets to "Langdon Road".

I see this mistake a lot (which is what prompted me to ask the question). It is barely noticeable when just viewing the map, but it really messes up routing through these streets and I usually find errors like these when investigating reported map bugs from skobbler

permanent link

answered 06 Oct '10, 15:32

GrahamS's gravatar image

accept rate: 28%

edited 06 Oct '10, 15:34


Indeed unconnected ways are a fairly common issue despite both potlatch and josm indicating quite well when a way is connected and when not.

One tool to help find and fix these errors is the OSM inspector - routing view. ( ). But as with all automated tools, it also has a number of false positives / negatives, so it can't be used blindly to fix these.

(06 Oct '10, 23:57) apmon

@apmon: thanks, I'll try OSM Inspector. I had a play with the "keep right!" tool mentioned by @scaii and found it was very useful at finding these errors. It refers to them as "almost-junctions".

(07 Oct '10, 09:51) GrahamS
7 is almost obnoxiously efficient at finding these.

(23 Feb '11, 22:21) Baloo Uriza

curiously, I tried both the OSM inspector and "Keepright", and I don't find the same misses! But from experimenting around my area I cans say both detect real lacks of connections :-) Hervé

(15 Apr '11, 13:38) Herve5

@Paul Johnson thanks for mentioning Keepright! I have used OSMI, MapDust, OpenStreetBugs and probably other QA tools, but Keepright is very cool and helpful.

(15 Apr '11, 22:24) ponzu

What's the easiest way to fix this in Potlatch?

(31 May '11, 21:41) Munchabunch

@Munchabunch: In this example I'd select the last node in the highlighted way, press the '-' (minus) key to delete it, then click on the Langdon Road way to connect them properly.

(15 Aug '11, 09:36) GrahamS

You can move the node over the way to which it should be connected, and press 'J' for join.

(05 Sep '11, 11:27) Richard ♦
2 has also developed an excellent QA tool (Osmose) that covers now the world, with live updates. Compared to KeepRight, it is often much more precise, more detailed, with useful fixes proposed, at least for Europe and its dependencies on other continents (except possibly Asia), and it is fresher (better fix things sooner than later and give help to the author, to avoid other problems). But unconnected ways, and unclosed boundaries ARE detected everywhere. Additionally, this tool speaks YOUR language (KeepRight just speaks English or has poor translations).

(27 Nov '12, 10:30) Verdy_p

The easiest fix in JOSM is to start dragging the ending node, then presssing CTRL while dropping the node to the other way to join with it. Note how the mouse cursor changes when you're pressing CTRL while still dragging the node... pressing 'J' with the node selected sometimes moves it and connect it to the wrong nearby way. Another solution: press CTRL to create the intersection node on the way, add the other node to the selection and press 'M' to merge the nodes (but this will move the newest node to the oldest one, so a straight way would become non straight)

(27 Nov '12, 10:37) Verdy_p

Also, when you see unconnected roads, you may just move back the final node up to the point where there's a pedestrian crossing. Add the crossing tag, the stop marks for vehicles, Then select that node and use the line mode to terminate the way to the crossing point. Finally add turn restriction on this new final node.

(27 Nov '12, 10:46) Verdy_p

This kind of problems is really easy to find using JOSM validator.

(03 Jul '14, 17:13) Mateusz Koni...
showing 5 of 12 show 7 more comments

Follow this question

By Email:

Once you sign in you will be able to subscribe for any updates here



Answers and Comments

Markdown Basics

  • *italic* or _italic_
  • **bold** or __bold__
  • link:[text]( "title")
  • image?![alt text](/path/img.jpg "title")
  • numbered list: 1. Foo 2. Bar
  • to add a line break simply add two spaces to where you would like the new line to be.
  • basic HTML tags are also supported

Question tags:


question asked: 06 Oct '10, 15:01

question was seen: 70,618 times

last updated: 20 Sep '20, 21:15

NOTICE: is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum