On one of the busiest travel weekends of the year, motorists are being advised to leave plenty of time for their journeys, particularly those travelling to and from Dublin Airport, where access is restricted.
With about 265,000 people flying in and out of Irish airports over the weekend, and events such as the All-Ireland senior hurling semi-final in Croke Park, the Tullamore Agricultural Show, the Dublin Horse Show and the Curragh Races, people will be on the move all over the country.
The most severe restriction will be on the road to Dublin Airport where the N1/M1 motorway at Santry between Coolock Lane and Collins Avenue will be closed all weekend until 6 a.m. on Monday. It will be closed for the next four weekends as work on the Dublin Port Tunnel continues.
A spokeswoman for Aer Rianta said their biggest concern was the road-work restrictions.
"We are expecting over 210,000 people in and out of Dublin Airport from Friday until Sunday," she said. There would be 1,600 flights landing and taking off, and of those 350 were holiday charters.
August was the busiest month, with 1.6 million going through Irish airports, and this weekend was one of the busiest in the year.
Diversions were in place, and recommended routes included the N2, N3 and the M50. Motorists were advised to avoid the Drumcondra approach to the M1 at Santry if possible,
An AA Roadwatch spokeswoman recommended that passengers plan their route, get a copy of the map if possible and leave with plenty of extra time.
In Dublin on Sunday, the Guinness All Ireland Senior Hurling Championship Semi-final between Waterford and Clare takes place in Croke Park at 3.30 p.m. The spokeswoman said delays could be expected on the N9, N10 and N7 from Waterford and the N6 and N4 from Clare.
Mr Tim Brick, the Dublin City Engineer, said the road closure would affect people going to Dublin Airport and Santry and north to Belfast.
He would advise motorists to leave early and would give the same advice to the hurling fans. There would be diversion signs all over the city, he said.
Iarnród Eireann is laying on three extra trains on the Waterford, Ennis and Limerick routes to Dublin for the match. These are all sold out. For the weekend, over 100,000 people will be travelling by rail, which is the average for summer.
Elsewhere, traffic restrictions and diversions will be in place around the grounds of Charleville Castle for the Tullamore Agricultural Show on Sunday.
In Cork, in the region of 25,000 to 27,000 people will be travelling in and out of the airport, and 30,000 to 33,000 passengers are expected to pass through Shannon Airport.
On Sunday, Bus Éireann will run special bus services from Dublin to the Curragh Races. The buses will depart Busáras 90 minutes before the start of the first race, returning to Dublin immediately after the meeting finishes.
Bus services between Dublin Airport and the city centre will run as normal and with the same travel times in spite of the traffic restrictions beginning this weekend, according to Aircoach, which provides the service.