[Talk-GB] UK postcodes on each side of the road

Lester Caine lester at lsces.co.uk
Mon May 19 15:44:53 UTC 2014

On 19/05/14 08:57, Marc Gemis wrote:
> from http://wiki.openstreetmap.org/wiki/Nominatim/FAQ
> <quote>
> Why doesn't Nominatim process addr:* tags on buildings[edit]
> For performance reasons buildings (and other low level features) are not
> fully indexed, but are instead simply inherit from their parent street.
> As such many addr:* tags except those directly related to the building
> are ignored. For instance add:town will never be used - instead the town
> of the road will be used.
> </quote>
> This is why I ask whether it works for you to have postcodes on the
> address nodes. My experiences is that they are useless for Nominatim.

I've been slowly adding details such as businesses in the local trading 
estates, and just adding postcode + building ID for each. Nominatim 
always picks up the correct location data even when a building is 
adjacent to a number of roads. But nominatim is not the only tool using 
address data, and not having to find adjacent roads because the postcode 
is available makes life easy. I have a complete postcode database which 
does of course help as well ;)

>     On 19/05/14 08:06, Marc Gemis wrote:
>               > and in this case, the street and other
>               > location data can be provided by tags on a street rather
>         than
>               > duplicating that data unnecessarily on every building ...
>              Surely that’s what associatedStreet relations are for.
>      > Does Nominatim already supports associatedStreet relations to pick up
>      > the postcode ?
>      > When I tried it 8 months ago, it just used it to find a street
>     segment
>      > (the first one in the relation). It then took the name of that street
>      > segment as the street name for the address.
>     associatedStreet is just another unnecessary layer in the way it is
>     currently defined. I see little point having the house identifier
>     duplicated. Where a postcode uniquely defines a set of higher level
>     relations then that is all we need. Where a postcode is not
>     available, then a link to a street way has a place, but in many
>     cases creating complex relations just makes the problem worse.
>     Personally I would prefer to see editors providing adjacent objects
>     as options for populating some of the tag elements, so if a postcode
>     is identified it can be duplicated.
>     Nominatim does work nicely without the need for the added
>     complication so I'd suggest at least in the UK we do not use
>     'associatedStreet' at all.

Lester Caine - G8HFL
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