Saturday 6 June 2015

When does a postcode start?

I have mapped a fairly large area, Hull and most of East Yorkshire. When there was nothing on the map I just added what I found but now there is a fairly complete road network. Keeping that up to date can be hard work - how do you know what has been added since the last time I looked? OS Locator is really valuable for this as new roads appear on there as OS maps them. It would be better to know developments are starting and get in early and I think there may be a way: postcodes.

New postcodes are allocated all the time. Around a thousand are created every month in GB. The Office of National Statistics publish a postcode list based on Codepoint Open data but with some extra stuff in there. One thing is the month the postcode was set up. Looking at the recent ones may let us find places that need surveying.

I've created a map to visualise these:

I hope this proves useful.


Anonymous said...

This is really useful way of tracking areas that were construction sites last time you surveyed them, but are now near completion or even finished. It is a great tool, my only criticism is how far out the locations are from where they should be.

For example in York:
the marker for YO31 7AA from 02/15 is not very near Heworth Parade on Mill Lane
the marker for YO31 7RH from 02/15 is the wrong side of the river from Chestnut Court
the marker for YO26 5TJ from 03/15 is not very near Peloton House on Old School Walk
the marker for YO31 9FA from 03/15 is maybe 1/2 mile from Upperdale Park

I don't if this mis-location is due to inaccurate data provided by Royal Mail.

It also shows up new postcodes for PO boxes at Post Office depots - I don't know if there is a simple way of filtering them out (or if that is worthwhile).


Chris Hill said...

These postcode 'centroids' have been created, I believe, manually by Royal Mail. The newer versions in the OS OpenNames dataset seem to be a true centroid, i.e. the real centre of the area. Sometimes this auto-generated one is not as helpful as the manually positioned version. I wonder if these newer postcodes are using the new algorithm and hence sometimes less helpful.