An estimated 80,000 people attended this year's concert at Slane Castle, which features acts including Kings of Leon, Elbow and Thin Lizzy.
Thin Lizzy, featuring the late Phil Lynott, were the headline act at the first concert at the venue in 1981.
Organisers said they hope new access routes will help to avoid a repeat of traffic chaos experienced by fans at the Oasis concert in 2009.
AA Roadwatch has said that traffic restrictions are place in and around Slane and the village is closed to all through traffic.
The car parks are located on the N51 Navan road, N51 Drogheda road, Kells/Slane road (R163) and on the N2 Dublin/Monaghan road north of the village.