Discouraged: Mapping things that are merely proposed or planned

Caution: It is highly disputed and widely regarded incorrect to map things in OSM that do not yet exist in reality. Things mapped in OSM should be real and verifiable.

The opinion of the majority of experienced mappers is:
(correct me if I’m wrong with this assumption)

  • Do not map features that are merely proposed or planned. Even doing this using proposed: prefixes is highly controversial.

  • It is perfectly fine to map things that are in the process of being constructed but not yet completed (using appropriate tags like building=construction or highway=construction).

Some mappers have put a lot of effort into mapping completely fictional things like long motorways or huge building complexes.

I’m hesitant to remove these things, because it effectively wipes out other people’s work that’s probably worth hours or days of dedication. On the other hand, it probably shouldn’t be on the map in the first place.

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Fine with construction mapping of ways but not when plopped in without a construction commencement date and a projected completion date affixed, no sign at all of preparatory work, no public works announcement board, funding etc which happens here frequently. Mapped constructions of public nature never seem to have links provided to the public works publication stating when work is planned to start, whether full funding is in place. Write it up and half the figments of imagination here can be removed.

Short for: No solid supporting data, be gone.


If there are no official links (that is from the state approving such construction) citing the schematic and locations of the fictional roads/buildings, and the user who mapped those things refuses to elaborate on that part, then they have to be removed.
We have in Greece last months such issue, for no apparent reason on why it’s done, as the communication with the mapper is not achieved.

I’d first try contacting authors via problematic changeset discussions. That is always a good idea. Be not only polite but welcoming and keep your mind open (the impact of that goodwill step cannot be overstated - that first contact can convert a new mapper to helpful member of community, or to a vandalizing troll for years to come).

Depending on their response (or lack thereof), and the extra details added on the tags (i.e. note, source etc.) I’d weight pro and contra.

  • If it looks like real deal and might become construction in forseeable time, I’d leave it as it is (as it will help greatly when converting it to construction when it starts).

    As you said - removing it will destroy someones effort, and the advantage is not really there (data consumers who don’t care about proposed: won’t be using it obviously, so from data consumer view at best you’d be saving few tiny bytes of download)

  • If it however lacks any extra details, mapper doesn’t respond in a week or more, and it generally looks like baloney then I’d remove it. (and consider contacting DWG if that pattern continues from that user even after few more failed attempts at contacting them)


I agree that mapping things that are “merely proposed or planned” is controversial. I have experienced first-hand (with significant consequences) that doing so is “discouraged,” at least initially before wider understanding of the specific example / project begins to allow heads to nod. Accordingly, I have mapped such things in specific cases and for specific reasons and our community continues to “allow” these, especially as wider understanding of the specifics takes place. I illustrate examples:

In California (USA) the nation’s largest public works project (~$100 billion) is underway: California High Speed Rail is being built. Without getting into the highly controversial and contentious details of this transformative infrastructure, its detractors, funding difficulties and “scaling back” (by our Governor) have presented great challenges to how OSM maps this. I have endeavored to capture statuses as best as OSM’s tagging (railway=proposed, railway=construction…) allows us. Please see California/Railroads/Passenger - OpenStreetMap Wiki and observe how a table of five segments of the project are colored green/yellow/red and rather accurately indicate progress and statuses. Note especially how the future-oriented segments (of Phase 2, colored red) are said to be “barely there” (in OSM) and how ephemeral is their existence in our database.

Here, we find significant segments of even the proposed segments where both planning (about $90 million of public works “design contracts”) as well as sometimes “on the ground” preparation work are “officially underway” (like bulldozing the right-of-way, even though no specific design is complete nor construction contracts exist), even in the “proposed” segments. It isn’t actual “construction,” yet, it is accurately tagged “proposed” because that’s what it is. This type of “this IS going to happen” (but hasn’t yet) is exactly why we have tags like state=proposed and railway=proposed. While something like this probably has (rarely) happened before, it isn’t likely that $90 million of design contract money will turn in to a project that never materializes. Given all that, and the real value that having these (even “barely there”) proposed (quite major) infrastructure elements in our map represent, the community has seen fit to allow them to remain.

In another example, “numbered national bicycle routes,” as part of United States Bicycle Route System - OpenStreetMap Wiki , a convention has emerged over the last 10 years to use state=proposed to indicate routes which (it is true) do not (yet) exist, but which are so close to becoming “Approved” (in the System, see our wiki for details on how this happens) that it really makes sense for us to enter them. It will only be a matter of weeks (or a couple months) before they likely DO become Approved, and this gives OSM the time and flexibility to enter these (often hundreds or even thousands of kilometers of) routes into our map while they are “on ballot” (for consideration to become Approved). After they DO become Approved, OSM merely removes the state=proposed tag, and (bicycle route) renderers re-render the dashed lines into solid lines, presenting the world with a beautiful, growing, accurate network of said routes. While there was quite prickly resistance to this process (as it emerged circa 2012-14), it has become both well-established (in OSM’s implementation of USBRS) and well-accepted among our community that “we enter routes (as proposed) like this.” And hence, it is OK.

The bottom line is that tags like highway=construction are always OK, if actual on-the-ground construction is taking place, but for the concept of “proposed,” we must be much more careful. “Proposed” (or “planned”) cannot be used for “fanciful musings” or “wishful thinking,” it may only be used when things like funding kick into reality, other “existence proofs” (for the project) begin to exist, AND that there is wide community acceptance / consensus that this IS taking place. Then and only then might a “proposed” tag be considered for OSM. Speaking first-hand, this is not easy to achieve, but it is well-worth the effort to do so, as I am certain that this makes for a map more complete with comprehensive, lifecycle-aware data. But again, it must be used carefully and with wide discussion that it is appropriate. I hope these two examples (CAHSR and USBRS) can be exemplary in how OSM does so.

Thank you for reading.