The Government has set midnight on January 19 as the date for the planned changeover from miles to kilometres on Ireland's roads.
From that date, speed limits and distances will be displayed in kilometres on all road signs throughout the country.
The changeover will cost around €10m and will coincide with a minor increase in the speed limit on motorways and a reduction in the limit on non-national roads.
An extra 23,000 signs are also being erected in addition to the existing 35,000 signs in a move that Junior Transport Minister Ivor Callely said should help improve road safety.