Concert-goers to this weekend's Oxegen Festival have been urged to leave their cars behind and take public transport to the event.
Three-quarters of the 80,000 revellers expected at the music festival at Punchestown Racecourse in Co Kildare will travel to the site today.
Gardaí are concerned that the constant rain of recent weeks will churn up many of the car parks, while the AA has warned of considerable congestion along the M7, with the Smurfit European Golf Open taking place at the K Club at the same time.
MCD, the promoters of Oxegen, have put a transport office in place on site to encourage concert-goers to use public transport.
Dublin Bus is laying on an express bus service from Parnell Square west every 20 minutes from noon today, while Bus Éireann will be providing a similar service from noon from Custom House Quay.
There will be a park-and-ride facility from Naas and Goffs on the N7 to the venue.
According to the AA, normal weekend traffic volumes will increase dramatically and motorists are advised to avoid the main routes in the Naas area unless it is essential.
AA spokeswoman Nicola Hudson said unnecessary journeys should be avoided on the N7, M4 and N81.
The Garda presence at the Oxegen site will be the biggest to date with 200 gardaí on duty for the weekend. A sergeant and 30 officers will patrol each of the two campsites and for the first time there will be a Garda station and two Garda offices on site.
This year there are a number of new initiatives to make life more comfortable for fans including 24-hour Centras in both campsites, a 24-hour restaurant and two Sónas tents which will offer gourmet food.
There will also be a powder room, podpads for upmarket camping and a site for camper vans.
