Mixed land use

Many city centres and even suburban centres have a mixture of land use.

In more densely populated areas it’s quite common to alternate apartment buildings (residential) with office buildings (commercial) with shops on the ground floor (retail). It’s not uncommon for the same building to be used for all three things. Even buildings with light industry in the ground floor routinely contain shops, offices or even apartments.

From reading the land use pages on the OSM wiki, you’d think that this never happens. The land use categories are described as if it were the norm for cities to be neatly separated into business parks, shopping malls, industrial areas and residential subdivisions. There are probably cities like that out there somewhere in the world, but I would think they are the exception.

Many city centres (e.g. London, New York) just aren’t tagged with land use, but from the discussions on the OSM wiki it seems as if the intention is ultimately to cover the entire globe with land use tags. I’d really like to tag my own city with land use because it would be nice to see the city and suburban centres distinguished from purely residential areas when the map is rendered. One thing I could do is pick a category, probably “commercial” or “retail”, and tag the entire city centre with this colour. That’s “tagging for the renderer” though so I’d rather not do that.

The only guidance I’ve found on the wiki seems to be to tag based on "predominant’ use. That helps in some easy cases, but an apartment building with a half dozen shops in the bottom is predominantly used (by volume) for apartments, but more people probably use it for shopping and the building next door could be an office building or a workshop.

So the upshot is that I don’t know how to tag land use in a city centre. I’ve spelled out the issues in detail because there doesn’t seem to be guidance on the wiki which makes me wonder if other people just haven’t encountered this problem. The people who came up with the original classification must have known that city centres exist, so there must be some way that the tags were intended to be used.

Any help would be much appreciated!

Take a look at key:abutters. In particular, abutters=mixed seems to fit your situation.

Yes, this is an issue, but not, I think, a serious one.

The way I have approached this is to think of the primary categories as a hierarchy, something like retail → commercial → industrial → residential. These days there is little overlap of industrial/residential, but in town and city centres if the predominant ground floor usage is retail I’ll tag the landuse as retail, if office buildings at ground floor level, then commercial and so forth.

Thus an area like that around Langstrasse in Zurich, where there are shops (and dodgy nightclubs) on the ground floor and in basements, offices in higher levels of buildings and apartments in the attics, would be tagged retail. This makes sense if you think about what you observe in terms of movement and types of people in the area (footfall). You will also see this reflected in rental values for the ground floor sites, local authority zoning regulations etc.

In South-east Asia where the shop-house is a long-standing feature of even small towns it might be reasonable to use a different tag.

Once you have applied the main landuse tag there is plenty of scope for adding additional tags, such as residential=*. For instance I have used residential=student_village to distinguish residential landuse for gated sets of flats which can only be rented to students. Once could also imagine adding tags for secondary landuse (e.g., landuse=retail, secondary_landuse=residential), although I am unaware of such usage.

The key to these things is to ask what you want to use it for. We have established that OSM landuse has a good correspondence (both qualitatively and quantitatively, see http://sotm-eu.org/talk@38.html) with other landuse/landcover schemes such as CORINE and Urban Atlas of the European Environment Agency. Example applications of landuse/landcover include: hydrological models (using assumptions about runoff and surface sealing), ecological information (my own interest), resource utilisation, traffic demand models, etc. Within OSM we may well use landuse to determine if areas have been adequately mapped: landuse=retail with no shop=* nodes or ways points to missing data and so forth.

Lastly, the abutters=* tag is more or less in abeyance. It is a useful tag if you only pass through an area and cannot survey landuse. With the widespread availability of aerial images this is rarely a problem now.


SK53, thank you so much for your response!

Some kind of precedence hierarchy was one of the ideas I’d been considering, but I didn’t want to launch into tagging (any more than I have) without guidance from someone with a better handle on best practice. I think the suggestions you give lend themselves to a very satisfactory land-use classification in my city.