All distance and speed-limit signs in the Republic will be transferred to metric by January 20th, it was announced today.
The Minister for Transport, Mr Seamus Brennan, confirmed all 50,000 signs in the State would finally be converted from miles to kilometres as required by EU law.
A major advertising campaign will warn motorists of the reforms and provide information to help them deal with the changeover.
The move will complete a semi-metric system in which the majority of distance markings are already in kilometres but speed limits are displayed in miles per hour.
Mr Brennan admitted the current system was "very confusing" and said the changeover had been delayed because of complications with the Border. But he said the change would finally bring the Republic in line with the rest of Europe.
"In some parts of the country we have signs in miles per hour and we have some in kilometres so it's very confusing," he said. "It's time that we totally and utterly removed the miles per hour and just dealt with one measurement only.
"I know the industry's been waiting for some time to have a definite date, so from January 20th on all cars imported will have to have a metric speedometer."
A metric changeover board will be established to oversee the process. It will be responsible for informing the public on the change and orchestrating a public information campaign that will begin immediately after Christmas.
The new regulations are most likely to affect drivers from Northern Ireland and the authorities are keen that the awareness campaign reaches across the Border. The Government stressed it would be especially significant to the province.
"There will be nobody left in any doubt by January 20th that when you see a sign it will be in kilometres," Mr Brennan said. "The 'km' will also be written on the sign itself so you know it's kilometres."
He warned that some care would be needed as existing cars are all dual so drivers will be operating on the smaller dial. New cars will all be in kilometres.
The Minister insisted no leeway would be given to speeding motorists who claimed they thought they were driving in miles rather than kilometres.
The changeover is expected to cost €5 million and will be funded by the National Roads Authority.