Thousands are arriving at the Oxegen Festival at Punchestown Racecourse in Co Kildare, which continues until Sunday.
Gardaí and the event promoters MCD have urged people attending to use the advanced park and ride facilities available for the event.
Details of traffic plans are available on the Garda and MCD websites as well as further information at the dedicated festival website, Oxegen.ie.
Oxegen 2011 features some of the world's biggest acts - the Black Eyed Peas, Foo Fighters, Coldplay and Beyonce headline the festival.
The first festival-goers arrived at the camp sites in Punchestown yesterday afternoon.
For those not planning on braving a weekend forecast of showers and sunny spells, park & ride facilities - with a free shuttle bus - are available at Goffs.
Dublin Bus and Bus Éireann are also operating special services to get people to and from the festival site over the next three days.
