OpenStreetMap
That's the 10 million dollar question for the day.
There is a lot of roads that appear on paper, but were never built and this can be quite frustrating for people who go out to survey a road that just doesn't exist, it's even more frustrating if you consider you may have tried to survey the same road multiple times yourself!
Luckily this hasn't happened to me, but at least one person on the talk-au list claimed to have done this :)
The problem has been compounded recently by property boundary data becoming available for 1/4 of Australia, while this boundary data doesn't have roads it has clear outlines where roads and waterways and other similar features exist in a void between boundaries.
We (the talk-au list) have previously come up a list of suggestions of how to tag non-existent roads without copying the road into the OSM DB:
However with the current dataset we do have a dataset we can copy, it's just a matter of coming up with a useful tag to identify these roads.
So far the tags we've thought up are:
highway=ghost_road
highway=paper_road
highway=gazetted_road
Can anyone think of anything better?
Discussion
Comment from Pink Duck on 13 October 2009 at 16:07
How about highway=proposed and highway=dismissed?
Comment from PhilippeP on 13 October 2009 at 16:19
What just not tagging what does not exist ....
Comment from JohnSmith on 13 October 2009 at 16:27
@PhilippeP I don't know how to make it clearer about why to do this, these roads exist on paper, they don't exist in reality and without some distinction that they don't exist you can't tell if they have or haven't been surveyed so people will go out of their way to survey something that doesn't exist, potentially a lot of someones surveying the same thing that doesn't exist multiple times.
The whole point is so people know what is worth spending time to survey and what is a waste of time because it doesn't exist.
Comment from JohnSmith on 13 October 2009 at 16:36
@Pink Duck, I think highway=proposed gets rendered, ideally these ways shouldn't be rendered, just visible in editors, they aren't dismissed either as they might get built in future if there is demand...
Comment from RichardB on 13 October 2009 at 19:36
Here's a possibility, a bit of an alternative.
Set up a wiki page/pages for each major area - and have a section detailing known mapping errors in that area (e.g. phantom roads) on other maps - akin to one we already have - Copyright Easter Eggs, but more localised. Make locals in your area aware of the page - as a mapping aid - so if they are going out to survey area xyz, they can look at the page before hand to check for phantom roads. You can be much more descriptive there as well. You could also use the wiki pages as an aid to collaborating with other OSMers.
Comment from rogerjmeier on 13 October 2009 at 21:28
@RichardB: These wiki pages could result in a nightmare to maintain.
@JohnSmith: What about "highway=nonexistent"... In fact You've chosen the right title for the diary entry. The other names ghost/paper/gazetted road are not easy to understand for non-english people.
Comment from marscot on 13 October 2009 at 23:19
if we are going to do this then it has to be right
it has to be tagged which type of highway it is/should be /made up to be
so I would go with
highway=motorway (or what ever kind it should be)
highway:false=yes means no render
if this tag is missing then its taken as true (saves going round every road again tagging highway:true=yes
it could also be
highway=motorway (or what ever)
highway:exist=yes/no
Comment from JohnSmith on 14 October 2009 at 00:20
@RichardB, within 50 sq km there is 100s of such roads, doing this any other way but non-geospatially would be pointless, no one would bother trying to look up if the road exists or not, not to mention the wiki would end up being next to useless because searching wouldn't accomplish much.
Comment from JohnSmith on 14 October 2009 at 00:47
@rogermeier at this point in time it's very difficult to get consensus on this and other topics in the broader OSM community and to some degree I've stopped bothering to a large extent beyond the talk-au community.
Comment from JohnSmith on 14 October 2009 at 00:49
@marscot because tagging something as highway=motorway would render, which defeats the purpose of the exercise as we only want these ways to be visible to editors otherwise people think they exist and go and "fix" them which in turn means you can't tell if they were surveyed or not.
Comment from RichardB on 14 October 2009 at 12:57
If there are hundreds of these within 50km^2, then perhaps the best suggestion is to use a more reliable atlas and complain to the company that makes them.
I can't imagine many people go tens of km out of their way to survey a single road - so a journey will not usually be completely wasted.
But if you must tag them, perhaps just put a note=* tag explaining why not to bother surveying. If you are just using it to effectively send an internal note to other mappers - and there are too many to use the wiki effectively, this seems sufficient.
Comment from JohnSmith on 14 October 2009 at 13:05
@RichardB If we do as you suggested and don't mark them what are we supposed to add a note against?
Comment from RichardB on 14 October 2009 at 16:13
Hold on, that's not quite what I said. If you are going to actually mark them, then if it's effectively an internal note to other mappers - then the tag semantics are probably not important. Anything will probably do, as long as it's obvious what is meant by it. A note=* tag on an otherwise untagged way would suffice, where * = some description which says, in plain English, what this way is doing here, and that mappers shouldn't waste their time by going out and mapping it because nothing exists etc.
There are plenty of objects all over the globe tagged with note=* intended as notes to other mappers - usually on objects that do actually exist - but perhaps not all information has been recorded, or something is incomplete etc. You probably don't need to overcomplicate things by defining a complex system of tags to describe that something *isn't there*.
Comment from vreimer on 14 October 2009 at 16:24
Not exactly a paper road but there is support for highways under construction
highway ... construction
construction ... (motorway, primary, tertiary ...)
I think there should be a highway seasonal category as well. A lot of mountain roads are closed in the winter, as well in northern areas there are winter roads.
Comment from seav on 15 October 2009 at 05:06
I agree with RichardB's solution. Draw an unconnected way approximately where the road is and just have a note=* tag and definitely no highway=* tags. This makes it visible to other editors but without affecting renderers.
Comment from JohnSmith on 15 October 2009 at 05:55
@seav as long as it's not a highway type that renders it shouldn't matter, I doubt anyone will intentionally render highway=nonexistent, also it shouldn't matter if it's conencted or not, just as long as it's tagged explicitly that it doesn't exist, using a note=* or otherwise.