Appeals have been made to remind road users to take particular care this weekend.
The Taoiseach, Bertie Ahern, and road safety organisations issued the call to motorists because of the increased volume of Bank Holiday traffic and the shorter evenings.
AA Roadwatch is advising drivers to use dipped headlights at any time in the day when visibility is reduced.
Because of the Cork Jazz Festival, traffic will be very heavy on the main N7 and N8 routes from today. The city centre will be extremely congested for the weekend.
Galway City is hosting two big sporting events: the 2006 International Rules First Test at Pearse Stadium tomorrow evening and the October Race meeting at Ballybrit on Sunday.
Both events will attract large volumes of traffic on the N6.
The Dublin City Marathon starts on Nassau Street at 9am on Monday.
There will be road closures along the route throughout the day and anyone intending to cross the city is advised to use the M50 Westlink or the Eastlink toll bridges.
Gardaí expecting 3,000 speeding offences
The Assistant Garda Commissioner, Eddie Rock, has said that he expects 3,000 drivers will be caught speeding over the weekend and that up to 400 drink-driving cases will be processed.
Mr Rock said people needed to plan ahead to ensure a safe weekend on the roads.
His comments follow Mr Ahern's appeal for drivers to exercise extra caution this weekend and with the onset of wintertime.
Mr Ahern said the Government was committed to doing more to protect life on the roads.
In a statement Mr Ahern said he wanted to make a particular appeal to parents and young people to do all within their grasp to make this a safe weekend for driving.
He said he was determined that as a nation we cease the unnecessary carnage, death, injury and grief caused by road collisions.
The Taoiseach said there was no quick remedy. However, he said the Government has provided the legislation and resources required by the gardaí, and was determined to do more.
Mr Ahern said the key ingredients were in place in terms of the Road Safety Authority, the road building provisions contained in the Transport 21 plan, and garda enforcement levels to ensure that no stone was left unturned to deliver in these areas.
