Gardai are expecting a capacity crowd of 80,000 people, attracted by the music and the sunny weather, to turn up for the Slane Castle open-air pop music festival tomorrow.
The music begins at 1 p.m., with Robbie Williams performing at 5 p.m., Manic Street Preachers due on stage at 6.30 p.m, and the main attraction, British group, The Verve, beginning at 8.30 p.m.
There will be Garda barriers on all major entry roads to Slane, about half a mile from the village: on the N2 from Dublin in the south and Collon in the north, and on the N51 from Drogheda in the east and Navan in the west.
Only vehicles with Garda passes - emergency vehicles and those belonging to local residents - will be allowed beyond these barriers.
The R163 from Kells will also be blocked off and there will be a sign at Kells advising concert-goers to travel via Navan. No roadside parking (except buses) will be allowed on any of these roads. Northbound traffic on the N2 will be diverted at Kilmoon Cross via Drogheda to Collon.
Southbound traffic will be diverted at Collon, via Drogheda to Kilmoon Cross.
The roadblocks will be in operation from 10 p.m this evening until 2 a.m on Sunday. Gardai warn that traffic will be particularly heavy in the area between 8 p.m tomorrow and 2 a.m on Sunday after the concert ends.
There will be large car parks adjacent to all the Garda roadblocks, with toilets.
Supt Eamonn Courtney of Navan, who is co-ordinating the operation, warned that no alcohol or tins which could contain alcohol would be allowed through the barriers. There will be a limited sale of alcohol on the concert site.
He said there would be a fully-equipped "field hospital" on the site, with up to seven doctors, seven ambulances and a cardiac facility. Nine Garda, civil defence and river rescue boats will patrol the River Boyne.
Supt Courtney appealed to parents intending to pick up their children after the concert by car to let them use public transport instead, as traffic restrictions would make it extremely difficult for cars to get near the concert site.
Dublin Bus will be putting on 120 buses to ferry concert-goers from the capital tomorrow morning. They will leave from Upper O'Connell Street - between the Ambassador cinema and the Dublin Bus offices - every 10 minutes between 8 a.m. and 1111.30 a.m. They will return from Ashbourne Road on the south side of Slane.
A Dublin Bus spokesman has warned people not to turn up tomorrow morning without a ticket which are available from Dublin Bus's offices in O'Connell Street or from the Ticketmaster outlets in HMV shops. He also advised people to buy the £12 return ticket and not expect to get a lift to Slane and a bus back. All Dublin Bus services which normally leave from Upper O'Connell Street will leave from Parnell Square West tomorrow morning.
All places on Bus Eireann coaches to Slane have already been sold. Ulsterbus will be carrying concert-goers from Northern Ireland and individual private coach companies will be bringing people from Cork, Limerick, Galway and other parts of the country.
Emergency Garda phone numbers over the weekend are Slane 041-24202; Drogheda 041-38777; Navan 046-21445.