Speed limits are to be reduced on 90 per cent of the country's roads as part of the changeover to metric signs later this month.
Under the changeover, all speed limits will be in kilometres per hour (k.p.h.) as opposed to miles per hour (m.p.h.) from midnight on January 20th.
The default speed limit is also being reduced on all local and regional roads by nearly 20 per cent to 80 k.p.h. (50 m.p.h.) from its current limit of 60 m.p.h.
As part of an information campaign, to be launched today, motorists are being advised that speed limits will also be increased slightly on motorways, dual carriageways and national roads, except in areas where specific speed restrictions apply.
A new low speed limit of 30 k.p.h. (19 m.p.h.) is also being introduced.
The campaign includes a mailshot into every home in the country advertising the changeover, with a conversion table to advise on the new limits.
The 70 m.p.h. motorway limit is to change to 120 k.p.h. (75 m.p.h.), the 60 m.p.h. limit on national roads and dual carriageways will rise to 100 k.p.h. (62 m.p.h.).
Lower speed limits on dangerous roads and built-up areas will also change from 50 m.p.h. to 80 k.p.h., from 40 m.p.h. to 60 k.p.h. (37 m.p.h.) and from 30 m.p.h. to 50 k.p.h. (31 m.p.h.).
Local authorities around the country, which are implementing the metric changeover, will replace 36,000 road signs around the country, and put up a further 23,000 signs in the days around the changeover date. All signs are expected to be in place by Monday, January 24th.
Yesterday a spokesman for the Minister for Transport, Mr Cullen, said he was also examining a reduction in the overall speed limit for large trucks and buses. He will invite submissions from various interested parties, along with expert advice from the Garda Síochána and the National Safety Council, before making a decision. "Safety is the key issue under which any proposals will be considered," he said.
As part of the changeover, from January 20th local authorities will also be able to set different speed limits on different times of the day on the same stretch of road, and different speed limits on opposing carriageways. There will also be a requirement on councils to hold a month-long public consultation before introducing new speed limits.
Yesterday members of the Metric Changeover Board, which has overseen the speed limit changes, said that safety was the key issue behind the changes.
The lower speed limit on country roads, the scene of a large proportion of fatal crashes due to speed, would be a major benefit, according to Mr Brian Farrell of the National Safety Council, and a member of the changeover board.
Mr Conor Faughnan of motorist lobby group, the AA, said he believed the changeover would go "very smoothly".