Gamma Blog: Eircode Administrative Boundaries Update

Eircode Administrative Boundaries Update

One of the most useful tables in the Eircode Address Database is the ADMINISTRATIVE_INFO table.  You can determine if a building is in a Gaeltacht area, what Local Authority it’s in, and its Townland.  Most usefully you can use it to link to the Census to get information at Electoral Division and Small Area level.  We have incorporated the latest data that provides compatibility with Census 2016, you’ll need to make a minor change to how you call our API to upgrade to the latest data.

(Small area boundaries for 2017 with Gaeltacht areas overlaid)

When Eircode was launched the latest Census was 2011.  Census 2016 has been released and Eircode have added fields to the latest ADMINISTRATIVE_INFO table to return both the original administrative data related to Census 2011 and updated data provided by Ordnance Survey that relates to Census 2016.

As described in the Eircode Product Guide and Release Notes for Q317 the existing fields have been overwritten with the new 2017 data.  The previous data is now stored in separate columns with _2015_ added to the column name.  This is a major change, but it was well flagged in the Q217 release notes by Eircode.  We upgraded our GetEcadData function in advance to take a parameter to return the required version (this defaults to 2015 if not supplied to ensure backward compatibility).

"administrativeInfo": {
 "ecadId": 1401182204,
 "release": "2015",
 "laId": 29,
 "dedId": 268098,
 "smallAreaId": 6349,
 "countyId": 1001000025,
 "gaeltacht": false },

To get the latest data you pass &administrativeInfo=2017 which returns the following

"administrativeInfo": {
 "ecadId": 1401182204,
 "release": "2017",
 "laId": 29,
 "dedId": 268098,
 "smallAreaId": 16896,
 "countyId": 1001000025,
 "gaeltacht": false },

 

What are the differences?

There are a number of differences, some minor and some major. A small number of properties along the coast that fell outside the detailed boundaries in 2015 are now inside the 2017 boundary data. This means approximately 50 properties have 2017 data but not 2015 data.

The Gaeltacht Areas don’t appear to have changed, but the GAELTACHT_ID does not match the GAELTACHT_2015_ID as you can see in the table below:

GAELTACHT_ID  GAELTACHT_2015_ID NAME
 1  6  MEATH
 2  7  WATERFORD
 3  4  KERRY
 4  5  MAYO
 5  3  GALWAY
 6  1 CORK
 7  2 DONEGAL

Electoral Division ID’s appear unchanged as there are still 3,441 of them that are combined to match the 3409 used by CSO in both Census 2011 and Census 2016.  There are a few hundred changes caused by minor changes in boundaries.  You can use the Look-Up tables to link to the respective CSO Identifiers.

The main difference is in the Small Areas.  There are 18,641 boundaries in the 2017 data compared to 18,488 in the 2015 data due to changes between Census 2011 and Census 2016.  Most importantly the SMALL_AREA_ID and SMALL_AREA_2015_ID values are completely different.  You can use the Look-Up tables to link to the respective CSO Identifiers.

Anything Else?

The detailed boundaries used by Eircode in previous releases were not available on the Government Open Data Portal data.gov.ie in detailed format, only generalised data was available. Ordnance Survey have released the 2017 data in full detail on the data.gov.ie site so anyone can replicate Eircode’s work in creating the ADMINISTRATIVE_INFO table.

One last thing

The design of Eircode does not include a hierarchy in the last four characters.  The only available dataset that could have been used to generate a hierarchical code was the Small Area dataset.  Some commentators suggested that this would allow census analysis by just providing a partial postcode rather than the full seven characters.  Less than a year after launch Census 2016 was undertaken which required changes to Small Area boundaries to reflect the change in household formation and to protect privacy.  This results in 43,362 Eircodes that have a different Small Area designation for the 2016 Census than they had for the 2011 Census.  Either a large scale project would be required to re-allocate new Eircodes for existing addresses and ensure they were updated in everyone’s databases, or the accuracy and usability of this feature would have eroded each Census.

Thankfully Eircode has a future-proof design that avoids these problems.

Please feel free to contact us for any advice regarding upgrading from 2015 to 2017 boundaries, especially if you have a Small Area-based solution.

@ 2017 Gamma.ie by Pat Donnelly

 

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