Mapping Dublin parish boundaries

TLDR: Go straight to the Dublin Parish Boundaries map [new URL April 2020].

In Ireland, most primary schools are run by the Catholic Church and the rules for enrolling often include complex lists of rules with those in the local parish often being preferred. This means when you are looking for accommodation to rent or buy it can be very important to know in advance which parish the property is located in.

The Dublin Archdiocese has a map of all the churches in Dublin but unfortunately it doesn’t seem to be working at the moment. Individual parishes sometimes have maps although these are often either static scanned documents or sometimes even hand-drawn sketches.

So how can we make these parish boundaries available on a modern map interface?

Fortunately for our purposes, the Catholic parishes are such an integral part of Irish society that the national Central Statistics Office reports their boundaries as part of its census data. This data is available under a custom non-commercial license from Ordnance Survey Ireland.

The data the CSO provide is in the form of Shapefiles but we can convert them to the more palatable GeoJSON format using the ogr2ogr utility from GDAL:

ogr2ogr -f GeoJSON -t_srs crs:84 new_file.geojson original_file.shp

Github provides a really useful GeoJSON renderer on their site but also for embedded maps. This means we don’t have to worry about creating a map and adding the parish boundaries as a layer.

The final piece of the puzzle is how to make the map available on the web. For this I used Cloud Foundry and in particular Pivotal’s hosted Cloud Foundry instance called Pivotal Web Services. [Disclaimer: I work for Pivotal but not on Cloud Foundry.]

I made a simple HTML page and using the Staticfile buildpack I was able to just do cf push to get the Dublin parish boundaries map up and running.

[Update April 2020: I’ve now relocated the map to Github pages.]

The final GeoJSON map as rendered by Github

One note of caution: the parish boundaries in the Census data may not correspond to those used by parishes or schools so please double check carefully before making any life-changing decisions!