Motorists caught using hand-held mobile phones while driving face penalty points for the offence from today.
A driver who is detected committing a mobile phone offence will get two points and be fined €60.
If drivers decide to challenge the offence in court and lose they will get four penalty points and a fine of up to €2,000.
RSA chairman Gay Byrne
The only defence for the use of a hand-held mobile phone in vehicles will be where a driver must contact the emergency services, using the numbers 999 or 112 for the Garda, fire service or ambulance, coast guard and mountain rescue services.
The ban on use of mobile phones does not apply to hands-free phones in vehicles. The new ban is legislated for in the Road Traffic Act, which was signed into law by Minister for Transport Martin Cullen in July.
The Act also allowed the introduction of random breath testing that started last month.
Just 17 people were killed on the State's roads from August 1st until yesterday afternoon. The figure represents just the second time road death numbers have fallen so low since 1980. The last month in which numbers fell to 17 was November 1999.
There were 24 deaths during August 2005 and 35 deaths during August 2004. Up to yesterday, 257 people were killed on the roads since the beginning of the year.
While this month's reduction coincides with the introduction of random breath testing of motorists by gardaí, the National Safety Council said yesterday "it was still too early to be definitive on the cause".
Road Safety Authority (RSA) chairman Gay Byrne said this morning he was "heartened" by figures that show the lowest toll for road deaths in August in a decade
"I think its very silly to draw a trend from one month's findings, but as far as it's indicative of anything it seems to be going in the right direction. . . . Not for the people alas who have died, not for their relatives, not for their families, not for their friends, but they will gain scant consolation from the fact that there were 'only'- in inverted commas - only 17 deaths.
"Seventeen deaths are 17 deaths too many, and that is not acceptable," Mr Byrne said.
But he told RTÉ: "I think at long last there 's a whole host of contributory factors being brought to bear, and people may at long last be getting the message, they may be beginning to get the message.
"Certainly in August we put the frighteners on people because of the random breath testing, and we pushed that through in legislation at the behest of the Minister quite quickly and brought it forward and I think at the beginning people got the message about random breath testing."
Mr Cullen today formally established the RSA, which has had an interim board operating since May.
The RSA now has formal responsibility for driver testing, driver licensing, issue of digital tachographs, enforcement of road haulage regulations, road safety promotion and research, oversight of NCT service and commercial vehicle roadworthiness testing, random roadside vehicle checking and driver vocational training.
It will also publish a new Rules of the Road and develop a road safety strategy for 2007 and beyond. The RSA's headquarters is in Ballina, Co Mayo, where 129 staff will be based.
In addition, the RSA will have 41 staff headquartered in Loughrea, Co Galway, and 139 staff based in 52 driving test centres across the country.