Motorists were encouraged to use public transport today as part of 'No Car Day', which has been marked in 34 countries.
The initiative is aimed at raising awareness of the travel options that are open to commuters.
Bus Éireann has been operating many city and town services either free of charge all day or between 10am and 4pm.
Previous bids to turn motorists into bus, train and bicycle users have been patchy.
The Environment Minister, Dick Roche, says his department, the Department of Transport and other relevant bodies are increasingly liaising with each other.
Mr Roche called on the public to make the 'right choice and truly make a difference'.
The Dublin Cycling Campaign said it would use the day to highlight what it terms the absence of necessary traffic planning or law enforcement which leads to gridlock.
