Some €4 million has been collected in speeding fines by the unmarked Garda Gatso van used by the traffic corps in the Louth/Meath division over the last five years.
At its peak, it was detecting 800 speeding offences a week but this has dropped to almost 300. The main offenders are not Northern Ireland motorists as is often claimed.
"At one time around 50 per cent of the fixed penalty or on-the-spot fines were being issued to Northern Ireland drivers but that is not the case any more and the percentage would be much smaller now," said Insp Gerry O'Brien, who oversees traffic management.
The unmarked van parks on the side of the road, catching unsuspecting motorists who are breaking the speed limit.
The Gatso technology, which gave it its name, allows gardaí to print a still picture of the driver of the car or lorry with its registration plate, and the date and time of the offence. It has detected approximately 100,000 drivers breaking the speed limits since it was first used in 1998.
The Garda division includes four of the country's busiest arteries, with upwards of 25,000 vehicles a day using the Dublin-Belfast road alone. For this reason it was the first area outside Dublin and Cork to be allocated the van.
Initially the Gatso was in constant use but it is now shared with four other regions and is on the road in the Louth/Meath division one week in the month. Insp O'Brien says most speeders are caught in the early morning.
"Between 6 a.m. and 8 a.m. we have discovered a lot of speeding and dangerous driving. Overall, Gatso has allowed us to detect offences we would not in the normal way; it is a deterrent because people have to be aware all the time and know they don't have to see the Garda to get caught. When you see we have an average of 20,000 detections a year, people realise we are serious and there is nobody in this region who doesn't know about the Gatso at this stage."
The fine for speeding is €80 and two penalty points, with further penalties added if the case is challenged unsuccessfully.