It would be great to think that there is actually a list of transport priorities. Experience shows us that policy decisions often respond to the strength of the lobby. Politically Navan railway line has become an issue mainly because it was planned that the M3 line would be extended to Navan and then the plan was dropped with so much more post 2008. Meanwhile motorway building continues apace despite the climate impact.
Dormitory towns are here to stay the model will not change its the same around the world you have bigger and bigger cities and the surrounding population are drawn to the centre. Railway is a good option