[Talk-GB] [Talk-scotland] Tagging of roads with adjacent named terraces

[Mark Goodge]

On 09/05/2022 10:37, Michael Booth wrote:
> I noticed someone raised a note about a similar problem further along 
> the road at Abbeyhill Colonies, so I opened an issue on Nominatim's 
> github: https://github.com/osm-search/Nominatim/issues/2051 Sarah says 
> the OSM tagging is wrong a name:left/right shouldn't be used and 
> addr:place should be used instead.

The problem with addr:place is that it isn't intuitively supported by 
the most common OSM editors. And, in normal English usage, "place" tends 
to be a synonym for a locality rather than a building, so, again, the 
average mapper isn't likely to consider using it in that context.

Postal addresses are complicated because, in the UK, there is a defined 
structure for them, but that structure is proprietary to Royal Mail and, 
in any case, doesn't easily fit with the standard OSM addr:* tags. But 
there is also a widely accepted convention that "Street address" means 
much the same thing as "first line of the address" in the majority of 
cases where a property is accessed directly from the outside (ie, is not 
a sub-unit of a larger property which neds to be entered first).

A consequence of that, though, is that people in the UK are used to 
using "Street address" for things which are not, physically, streets. 
The "street address" of a named terrace, or colony, for example, is 
generally accepted to be the name of the terrace or colony rather than 
the adjacent highway (even more so for a colony, actually, where the 
adjacent highway has no name).

> As for parentstreet, having tried to follow all the addressing 
> discussions a few months ago I'm still not sure of its definition or 
> where it should be used.

addr:parentstreet should be used where there are two different street 
level address lines in the same postal address. To give a real life 
example of an actual postal address, this one near where I live:

1 Rightons Court
High Street
EVESHAM
WR11 4DD

In this case, it should be tagged as

addr:housenumber=1
addr:street=Rightons Court
addr:parentstreet=High Street
addr:city=Evesham
addr:postcode=WR11 4DD

This is different to the way that Royal Mail do it - they would call 
High Street the "thoroughfare" (aka street) and Rightons Court the 
"Dependent Thoroughfare" (aka substreet). But a fairly lengthy 
discussion on this list concluded (rightly, in my opinion) that 
substreet/street is less intuitive and more likely to generate errors, 
than street/parent_street.

The key reason for that is that a fully functional postal address in the 
UK can almost always be formed simply by taking the lowest level street 
address line, the post town and the postcode. In this case, if someone 
omits "High Street" from the address, post will still get there and the 
address can easily be found by someone looking for it. But they omit 
"Rightons Court", then you end up with "1 High Street", which is a 
different place entirely.

> People seemed to be suggesting it should be used for a street coming off 
> another street, but surely you just use the actual street name instead 
> of adding another one? (otherwise where do you stop!) I see it has been 
> used here off Easter Road - 
> https://www.openstreetmap.org/node/9423069429/history - but is it really 
> necessary to have a parentstreet here?

In this case, no, because Easter Road doesn't actually appear anywhere 
in the actual postal address. addr:* tags should be simply the postal 
address, not the geographical address.

As a rule of thumb, when tagging postal addresses in the UK, then, 
unless there is good reason otherwise, then:

addr:street = the street (or, where appropriate, terrace or colony) 
named in the first line of the address

addr:city = the post town (even if it's not a city!)

addr:postcode = the postcode

and then, in between addr:street and addr:city, any other tags necessary 
to complete the postal address. That may include an addr:parentstreet 
for locations such as the one above, and/or an addr:suburb (or other 
appropriate tag) where the postal address contains an additional 
settlement name between the street address and the post town.

There's a fairl good summary of that on the wiki:

https://wiki.openstreetmap.org/wiki/Addresses_in_the_United_Kingdom#addr:substreet,_addr:street_&_addr:parentstreet

This also explains the reasoning behind the current consensus on using 
addr:street/parentstreet.

Mark