I will be arriving at Dublin airport on 13th of August and need to get from the airport to the DART to go WEST to Roscommon. Question #1, what is the best way to get to the DART, via bus or airlink; question #2, what station would I go to in order to get the DART west to Roscommon, particularly Boyle station?

There is some sort of special bus that brings you from the airport to
CONNOLLY STATION. From Connolly Stataion you get the mainline train
("big train") to Boyle, the terminus of the train is SLIGO.

(BTW: The DART is not what you want: It just runs along the coast in
Dublin City)

Enjoy!

Thanks. I think I can take an airtrain as well. I see the rail line that I have to take going towards Sligo. Thanks for letting me know that it is not the DART.

The mainline station you want is Heuston, not Connolly (see http://www.irishrail.ie/ ). To get to Heuston, look at the airport for Bus 748 and check with the driver -- only some go to Heuston (or you can take a bus to Connolly, and use the LUAS tram service to link you to Heuston, but it's a bit more bother).

Thank you for your response, but I have another question. If that's the case, why would I take the bus from the Airport to past Connolly Station to go to Heuston, to get the rail out to Sligo? I may be misunderstanding my rail map. thanks.

I just spoke to someone at Dublin Bus and he told me to take #747 which indicates it is a 10 minute ride.

The mainline train from Sligo via Boyle comes into / goes out from DUBLIN CONNOLLY, to the best of my knowledge, not Dublin Heuston. A bus/tram would link Connolly to heuston if that were the route required.