The Government has decided that road signs referring to miles for distances and speeds will be withdrawn in September.
The Minister for Transport, Seámus Brennan, said he intends to pick a date in September when all road signs will go metric and will be shown in kilometres.
Speed limit signs will also be changed to kilometres per hour.
The scheme will include a reduction from 60mph to 50mph on some country roads. Under the new scheme this will be shown as 80kph.
The minister said a major information campaign will be put in place to help motorists deal with the changeover.
Earlier, Mr Brennan announced an expansion of the planning programme for national roads.
The minister said investment in 2004 will total €1,223 million, which he said will allow work to start on 17 major new schemes.
Work will also continue on 17 other schemes, 12 of which are due to be completed this year.
The minister also announced that significant progress had been made on plans to open up three vital corridors to the north, south and west.
The M1 to the North is due to be completed in 2006, the other two motorways from Dublin to Cork and Galway are due to be completed at the end of 2007.
