Raw data files available on SonraíOscailteTÉ/OpenDataNI. The files are mainly in geojson file format. I used the Python package pandas to process the data and create the visualisation. The rail way system in Northern Ireland is quite limited but it used to be much more expansive. Fig. 1 shows the current extent of NI Rail
The dataset contains locations of industrial heritage sites across Northern Ireland. Plotting the rail related data points gives Fig 2:
yellow = old stations
red = viaducts
orange = rail bridges over roads and road bridges over rail
purple = level crossing
green = other
The difference in the West is clear - virtually all the old railways in the West have gone. !00% of rail in counties Tyrone and Fermanagh have gone.
The following Wikipedia page lists all closed stations across Ireland.
The following post on my code-examples blog shows the code used to generate the visualisation.