A quarter of all drivers are regularly breaking the speed limit, according to the National Roads Authority.
Figures compiled from automatic road traffic counters installed by the NRA at more than 100 locations throughout the State also show speeding habits are seasonal: in summer, more than one in four cars break the speed limit (27.5 per cent), while in December the figure falls to one in six (17 per cent).
With trucks, however, the percentage breaking the law is even higher, with as many as 41.5 per cent of all trucks breaking the speed limit in March.
The lowest percentage number of trucks recorded speeding, between September 1997 and October 1998, was 36 per cent, recorded in September 1998.
The NRA has also compiled a table of the State's worst locations for speeding vehicles, based on the data from the roadside counters.
Highest is Dundalk Bridge on the N1 in Co Louth, where 90 per cent of cars exceeded the 30 m.p.h. limit between March and September of this year.
Second was Julianstown, Co Meath, on the N1 where more than 80 per cent of cars exceeded the limit in August 1997 (this figure was down to approximately 72 percent in August 1998).
Third was on the N25 at Rosslare, Co Wexford, where the percentage of cars exceeding the speed limit rose to approximately 78 percent in February 1998, while between October 1997 and May 1998 the figures for the percentage of cars that were speeding never fell below 70 per cent.
Fourth was Turnapin North on the M1, Co Dublin, where in May 1998 some 75 per cent of cars were found to be speeding. For the duration of the study, August 1997 to September 1998, the number of cars detected speeding here never fell below 70 per cent.
In fifth position was the N11 at Jack Whites, Co Wicklow, where between early January and July of this year, 50 per cent of cars exceeded the speed limit.
According to the NRA, even in locations where it can be shown that few if any cars exceed the speed limit, this does not necessarily imply that drivers are better behaved. "It's more likely that there is a severe bend on the road and drivers have no choice but to slow down," said Mr Mick Foster, a spokesman for the NRA.
The vehicle counters and speed checkers are built into the road surface and are being increasing deployed by the NRA.
By the end of this year the authority expects 108 to be operating on all major routes. The figures are also a "lifestyle indicator", according to Mr Foster. who told The Irish Times that peak speeding numbers in spring or early summer, were as a result of "holiday-makers who want to get away for the weekend" while the low figures recorded in December were "a result of the fact that people fear the greater law enforcement at that time of the year".
Mr Foster says the figures are disappointing, pointing to the difficulty of getting the message across that speed is "politically incorrect".
"You never, ever hear of anybody boasting that they drink and drive now.
"But you still hear them say they made it back from Cork in double quick time. This is very disappointing," he said.
