Cars account for over 2/3 Ireland’s CO2 emissions from road transport, the rest being goods vehicles. Railways are barely a rounding error, which makes sense as we have a tiny rail network. http://www.epa.ie/pubs/reports/air/airemissions/ghg/nir2019/Ireland NIR 2019_Final.pdfThe railways, HGV and industrial equipment like diggers uses far more
But regardless of that, it’s cars that are used most on city streets where pollution is worst, and we have a ready means of significantly improving car emissions today (electrifying them) whereas electrifying the likes HGVs and intercity trains is not as easily done. So why not start with cars...