The Dublin Suburban Rail (Irish: Iarnród Bruachbhailteach na mBaile Átha Cliath) network, is a railway network that serves the city of Dublin, most of the Greater Dublin Area and outlying towns. The system, now branded as DART/Commuter, is made up of five lines:
Northern Commuter - Dungalk to Dublin Pearse
South Eastern Commuter - Dublin Connolly to Gorey
Western Commuter - Dublin Pearse / Docklands to Longford.
South Western Commuter - Dublin Heuston to Kildare.
DART (Dublin Area Rapid Transit - Greystones to Howth/Malahide.
The lines are owned and operated by Iarnród Éireann, however the Luas (light rail) system is not officially part of this network, and is not operated by Iarnród Éireann. As of October 2006 only the Luas Red Line between Connolly and Heuston stations is featured on DART network maps.
Services run from approximately 06:00 to 23:30. Services are frequent on the DART line (usually every 15-20 minutes off peak, more frequently at peak times). Services are also frequent at peak times on the Western and Northern lines (approximately every fifteen minutes). However off-peak services on the Western and Northern lines can be as infrequent as hourly or more. Service frequency on Sundays is even less. However, from 14 January 2007 the Western line has operated an hourly service from 09:30 to 18:30 on Sundays.
Services are less frequent on the South Western line, however there are trains approximately hourly. Since 14 January 2007 the South Western line has operated on Sundays for the first time, with five services each way. The South Eastern line is the least frequent, with only four trains a day at present
Main source: Wikipedia