[Talk-GB] Armchair-mapping postcodes (was: B72 is a wrap)

Ed Avis eda at waniasset.com
Tue Feb 15 18:06:35 GMT 2011

Andy Robinson (blackadder-lists <ajrlists at ...> writes:

>>OSM's coverage of streets is much better than its coverage of buildings.
>>Might it make sense to tag postcodes on ways?
>Nope, streets often have more than one postcode for the properties on that
>street. It's not the street that has a postcode anyway, it's the delivery
>points for the mail, i.e. the letterbox in your front door.

That is true.  But given that in many areas we have good streets but not good
buildings, there may be value in adding a simplified version of the postcode
data in which a way is tagged with the postcode(s) that apply along it.

The use case I am thinking of is the common 'enter your postcode' on business
websites or over the telephone.  Given a postcode you can find the street (or
streets) which it corresponds to.  This means that a house number plus postcode
is sufficient to make the whole address.

A simplified tagging of postcode=x;y on a way would let OSM be used to map
postcode to street name.  It would not be quite as precise as the PAF,
giving two possible streets in some cases where there is only one in reality.
But it might be useful for small organizations who want to give people an easy
way to enter their address, without paying for the PAF data.  (Potentially, a
web service could offer this lookup and feed back statistics on which streets
were chosen, to be used to fix up the OSM data.)

By no means should tagging postcode on ways replace the more thorough building-
by-building survey with street numbers, but it might be a first step, just as
we usually tend to put the street network in first with no buildings and come
back for the extra detail later.

Ed Avis <eda at waniasset.com>

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