Transportation between Birr and Dublin

Yes, routes 845 and 847 run by Kearns Transport- https://kearnstransport.com/dublin/

I guess the better question should have been...is taking the bus worth it? It looks like it is only 75 miles from Dublin to Birr. However, according to what I'm reading, the bus takes 3 1/2 hours. Is that correct?

It is 140km, which is just under 90 miles. ViaMichelin gives a drive time of 1:40 by car on the bus route or 1:50 via Kildare. The bus does it in 2:15 to 2:20 to Heuston station, Dublin.

Then, depending on your destination in Dublin hop on LUAS from Heuston. Only you can decide if the 30 minute time "penalty" is worth it versus driving and parking in central Dublin.

Or are you heading to Dublin Airport. Is that where 3:30 by bus comes from? Even then, changing bus at Heuston 3 hours by bus is closer to the mark vs a drive time of 1:50.

Incidentally it's odd that Birr crops up tonight. In "real life" I have been doing a family tree today for someone, of a man with the wonderful name of Theophilius Inkerman Cartwright, child of an ex Crimean war soldier who was in barracks at Birr before being sent to garrison at Halifax, Nova Scotia.

It has no bearing on your query, just struck me as a co-incidence.