DRIVERS are unable to read giant new motorway signs at night -- because of the dewy Irish climate.
The National Roads Authority (NRA) yesterday admitted the problem, which is being blamed on a build-up of dew on the thousands of new blue and white signs.
This is stopping the light from car headlights reflecting back to approaching motorists.
As a result, drivers are frequently unable to make out the writing on the expensive signs, which appears as "grey and hazy".
Top engineers with the NRA are now carrying out experiments to see if special coatings can be applied to thousands of signs along the new 750km-long network of motorways and dual carriageways.
The dew problem emerged yesterday as the M7 Nenagh to Limerick motorway, part of which sank into a bog, was officially opened by Transport Minister Noel Dempsey.
The 38km stretch of road, which cost €424m, will result in time savings for the 20,000 vehicles travelling between Limerick and Nenagh every day and bypass several accident blackspots.
Mr Dempsey said that experts were working on the sign problem to see if a solution could be found.
"This is a difficulty that is not just specific to Ireland," the minister added.
Fred Barry, NRA chief executive, blamed climatic conditions in Ireland for the problem, but vowed that they would keep working to find a solution.
According to Sean O'Neill, NRA spokesman, the problem is caused by a build-up of dew on signs when they get very cold at night time.
While the signs were manufactured to the highest international standards, the light hitting the dew-covered signs is refracted out, instead of being reflected back to the motorist.
"The signs can look cloudy and grey," he added.
"We have the highest standard of reflectivity on the signs in Europe. But the primary issue is not the reflectivity, it is the dew," said the NRA spokesman.
"Ireland has the climatic conditions which are conducive to a build up of dew. It is an atmospheric issue. It is a problem.
"Our engineers are looking at experimental coatings."
Mr O'Neill said other countries experienced similar problems in certain weather conditions and denied suggestions that there was no such problem along UK motorways.
"This is also an issue in other places such as Frankfurt. The sign looks grey, and you cannot read it properly."
The M7 Nenagh to Limerick road was opened more than a year behind schedule.
The construction of the 38km road from Annacotty to Nenagh in Co Tipperary was contracted to Bothar Hibernian almost four years ago. It was due for completion in June 2009.